Southern and Eastern Scalefish and Shark Fishery

​​​​​​​​​​Chapter 8: Southern and Eastern Scalefish and Shark Fishery

F Helidoniotis, A Koduah and S Nicol

FIGURE 8.1 Area and sectors of the Southern and Eastern Scalefish and Shark Fishery

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8.1 Description of the fishery

The Southern and Eastern Scalefish and Shark Fishery (SESSF) is a multisector, multigear and multispecies fishery, targeting a variety of fish, squid and shark stocks. The management area covers almost half the area of the Australian Fishing Zone (Figure 8.1), and spans both Commonwealth waters and the waters of several Australian states under Offshore Constitutional Settlement arrangements. A number of the reserves within the Commonwealth marine reserve network established by the Australian Government fall within the SESSF management area (AFMA 2016).

The SESSF remained the largest Commonwealth fishery in terms of volume caught in the 2015–16 fishing season. In 2015–16, the gross value of production (GVP) of the SESSF was $73 million, accounting for 17 per cent of the GVP of Commonwealth fisheries.

The primary mechanism for controlling the harvest of stocks in the SESSF is through the allocation of annual total allowable catches (TACs). TACs are determined for all key commercial stocks and several byproduct species. The TAC for each stock is distributed among fishers as individual transferable quotas for the fishing season. In addition to TACs, management arrangements in the SESSF include limited entry, gear restrictions (for example, restrictions on mesh size, setting depth, number of hooks and trap dimensions), spatial closures, prohibited species (for example, black cod—Epinephelus daemelii), trip limits for certain species (for example, snapper—Chrysophrys auratus), codes of conduct, move-on rules, and requirements for observer or video camera coverage and vessel monitoring systems.

The SESSF was established in 2003 by amalgamating four fisheries—the South East Trawl, Great Australian Bight Trawl, Southern Shark Non-trawl and South East Non-trawl fisheries—under common management objectives. The 2003 management plan for the SESSF came into operation on 1 January 2005 (amended in 2009). Originally, each of the four fisheries had its own management advisory committee. In 2009, the Australian Fisheries Management Authority (AFMA) created the South East Management Advisory Committee (SEMAC) to provide advice to the AFMA Commission on management measures for the entire SESSF. The Small Pelagic Fishery Management Advisory Committee and the Squid Management Advisory Committee became part of SEMAC in 2010, whereas the Great Australian Bight Trawl Sector Management Advisory Committee remains separate.

Landings in the SESSF have generally decreased over time as a result of reductions in fishing effort. In 2016–17, landings in the Commonwealth Trawl Sector (CTS) and the Gillnet Hook and Trap Sector (GHTS) were 8,691 t, representing around 43 per cent of available quota. Landed catches for other sectors of the SESSF are reported in the relevant chapters.

The SESSF was one of the fisheries targeted by the Securing our Fishing Future structural adjustment package (2006–07), which was intended to halt overfishing, improve economic conditions and efficiency of fishers, and recover overfished stocks. The package reduced the number of fishing vessels by purchasing fishing endorsements. Although this contributed to lower landings and GVP, net economic returns (NER) improved in the years immediately after implementation of the SESSF harvest strategy framework (HSF) and the Securing our Fishing Future structural adjustment package (George & New 2013; Ward et al. 2013). Since then, other factors have come into play, and NER for some sectors of the SESSF have declined. Trends in NER are reported in the relevant chapters.

8.2 Sectors of the fishery

Current management arrangements are structured around the four primary sectors of the fishery: the CTS, the East Coast Deepwater Trawl Sector (ECDTS), the Great Australian Bight Trawl Sector (GABTS) and the GHTS.

The status of the stocks taken in these sectors is presented in Chapters 9, 10, 11 and 12, respectively. The GHTS includes the Scalefish Hook Sector (SHS), the Shark Gillnet and Shark Hook sectors (SGSHS), and the Trap Sector. In this report, the SHS is reported with the CTS (Chapter 9) because most of their target species are shared. The SGSHS is reported separately (Chapter 12). The Trap Sector is not reported in detail because of its low fishing effort and landings.

8.3 Harvest strategy performance

A tiered HSF has been applied in the SESSF since 2005. The framework has evolved since its introduction, particularly after the release of the Commonwealth Fisheries Harvest Strategy Policy (HSP; DAFF 2007). The current SESSF HSF applies to all sectors and each stock under quota, and is assigned to one of five ‘tiers' for assessment purposes under the HSF (AFMA 2014; Haddon et al. 2015). The assessment tiers have been developed to accommodate different levels of data quantity, quality or knowledge about stocks. Tier 1 assessments are the highest quality and use a fitted statistical catch-at-age model with high-quality data. Tier 2 are the same but with low-quality data. Tier 3 rely on analysis of catch curves, tier 4 on catch-per-unit-effort data and tier 5 on catch-only, model-assisted data-poor stock assessments. Although described in the HSF, tier 2 assessments are not currently applied in the SESSF.

The target and limit reference points for each tier are prescribed by the HSP. All tier levels generate a recommended biological catch (RBC) through associated harvest control rules that are intended to move stock biomass towards the target reference point (AFMA 2014). RBCs provided by resource assessment groups are translated into TACs through a set of predetermined rules, which include deductions for discarding, recreational catches and state catches. The SESSF HSF has been management strategy evaluation tested to ensure that the harvest control rules are robust to model structure and parameter uncertainties (Fay et al. 2009; Little et al. 2011; Wayte 2009). The level of precaution applied in RBCs increases from tier 1 to tier 5, reflecting the assumption that the level of uncertainty increases with the assessment tiers. Under the HSF, TACs are reduced using discount factors of 5 per cent for species assessed using the tier 3 harvest control rules and 15 per cent for tier 4 harvest control rules, unless other management arrangements are considered to have introduced an equivalent level of precaution. A prescribed discount factor for tier 5 has not been determined under the HSF. The Southern and Eastern Scalefish and Shark Fishery Resource Assessment Group (SESSFRAG) has also produced guidelines on the implementation of various post-assessment ‘meta-rules' (for example, the large change–limiting rule and discount factors). Since 2009, there has also been a move towards greater recommendation and implementation of multiyear TACs in the SESSF, whereby an RBC (incorporating appropriate precaution) is estimated for a period longer than one year—typically three, although five years is also used. This provides a basis for setting TACs for longer periods, which provides greater stability for industry, and reduces the number of annual assessments and therefore the assessment cost.

The SESSF includes several stocks that are classified as overfished (that is, the current biomass is estimated to be below the limit reference point). These overfished stocks are blue warehou (Seriolella brama), eastern gemfish (Rexea solandri), gulper sharks (Centrophorus harrissoni, C. moluccensis, C. zeehaani), school shark (Galeorhinus galeus), redfish (Centroberyx affinis) and orange roughy (Hoplostethus atlanticus) in two zones (southern and western).

For overfished stocks, the harvest control rules in the SESSF HSF, in line with the HSP, recommend a zero RBC. AFMA allocates incidental catch allowances to permit small catch volumes of these species when fishers are targeting other species. Although the SESSF HSF does not provide guidelines for setting these catch allowances, the SESSFRAG-agreed process uses companion species analysis and/or quantitative stock assessment models. These provide the SESSFRAG with estimates of the quantities of species likely to be taken as bycatch when fishing for other species and the impact that such fishing mortalities have on time frames for rebuilding to the stocks' limit reference point. These data feed into advice on the appropriate setting of incidental catch allowances. An important aspect of setting an incidental catch allowance is that there is a trade-off between setting a TAC too low, which might then result in discards, or too high, so that rebuilding is not achievable (Haddon et al. 2016). In some cases, the level of fishing mortality that would allow a stock to recover within stipulated rebuilding time frames is uncertain. In other cases, even with zero catch, stocks may not rebuild within stipulated rebuilding time frames because of their low natural productivity at low stock size (Ward et al. 2013), ‘non-average' conditions (for example, below-average recruitment), shifts in the ecological relationships between stocks and their environment (‘regime shifts'), or changes in other environmental variables. Similarly, the ability to immediately detect recovery of overfished stocks may be limited if fishers actively avoid depleted stocks (for example, move-on rules [Haddon et al. 2016], area closures), because information from fishery logbooks or the Integrated Scientific Monitoring Program (ISMP) is no longer likely to be fully representative of the stock or comparable with historical information.

Gillnet
AFMA

Most quota species caught in the SESSF are currently managed towards a BMEY (biomass at maximum economic yield) target, although only a few of these targets are estimated using a bio-economic model because of the data requirements and complexity of these models. For species that have had a maximum sustainable yield (MSY) estimated, a 1.2BMSY proxy for BMEY is used as the target. For other species, a target that is equivalent to the proxy 0.48B0 (48 per cent of the unfished biomass) is applied. Economic performance of the fishery could possibly be improved by optimising targets for a combination of the more valuable quota species, rather than the default proxy applied to individual species. Consideration is also being given to alternative approaches to setting targets for secondary species (that is, those that are not targeted and contribute a small proportion of the NER). Following guidance from the SESSFRAG, the Slope Resource Assessment Group (which is responsible for monitoring, assessment and reporting of upper continental slope and deepwater species) and the Shelf Resource Assessment Group (which is responsible for monitoring, assessment and reporting of species associated with the shallow areas of the continental shelf)1 recommended targets at BMSY levels, below the BMEY proxy, for several secondary species. AFMA has agreed to adopt these alternative targets (SEMAC 2014). Secondary species managed to the BMSY proxy target include john dory (Zeus faber), ocean perch (Helicolenus barathri, H. percoides), ribaldo (Mora moro), sawshark (Pristiophorus cirratus, P. nudipinnis) and elephantfish (Callorhinchus milii).

Differences in the profitability of the various fishing methods, and species that are caught together in the CTS and the GHTS complicate the optimisation of harvests to obtain MEY at the fishery level. Augmenting current stock assessments with available economic survey data may provide a cost-effective means of estimating MEY targets for a broader range of species. Pascoe et al. (2015) noted that, because detailed bio-economic models for many fisheries are unavailable, some form of cost-effective proxy measure is required to estimate approximate target reference points. The research recommended that the designation of a simple default proxy target reference point needs to be reconsidered, particularly in the case of multispecies fisheries. The research also noted that the benefits of identifying an appropriate set of criteria for determining how many and which species should be managed at different targets could result in lower costs and lower discards, and potentially higher profits. This work presented a framework that may inform future research to develop target reference points that are consistent with the HSP in multispecies and mixed fisheries, such as the SESSF.

For the GABTS, the development of a bio-economic model (Kompas et al. 2012) for the sector's two key target species (deepwater flathead—Platycephalus conatus, and bight redfish—Centroberyx gerrardi) has allowed TACs to be set in line with achieving estimated BMEY targets. Given that the models were published in 2012, the Great Australian Bight Resource Assessment Group has noted that BMEY targets set for the GABTS may need updating to better reflect changes to cost and profit input parameters.

8.4 Biological status

The number of stocks assessed for status in the SESSF increased from 24 in 2004 to 37 from 2009 to the present. The number and percentage of stocks classified in each status are presented below.

With regard to fishing mortality status, of the 37 stocks (34 under quota) assessed across the SESSF in 2016 (Figure 8.2):

  • 31 stocks (84 per cent) were classified as not subject to overfishing
  • 0 stocks (0 per cent) were classified as subject to overfishing
  • 6 stocks (16 per cent) were classified as uncertain with regard to the level of fishing mortality.

For biomass status (Figure 8.3):

  • 27 stocks (73 per cent) were classified as not overfished
  • 7 stocks (19 per cent) were classified as overfished
  • 3 stocks (8 per cent) were classified as uncertain if overfished

Controlling fishing mortality is the primary management lever for AFMA. The year 2013 was the first year since 2006 that no stocks had been classified as subject to overfishing. This has continued for subsequent years. Within the SESSF, TACs are determined after considering state catches; discards; recreational catches; social and economic and Indigenous requirements (Haddon et al. 2015). Discarded fish can pose a problem because there is often a high level of uncertainty around discard estimates. Because discarding is poorly reported, it becomes difficult to estimate the true level of fishing mortality (Haddon et al. 2016). With respect to biomass, several stocks that are classified as overfished remain classified as uncertain if subject to overfishing, meaning that it is currently unclear whether the current level of fishing mortality will allow the stocks to rebuild to the limit reference point within a biologically reasonable time frame, as required by the HSP.

Overfished stocks are stocks that are estimated to be below the limit reference point of 20 per cent of unfished levels (0.2B0). The stocks classified as overfished in 2016 are blue warehou, eastern gemfish, gulper sharks, orange roughy (southern and western zones), redfish and school shark. AFMA continues to work with stakeholders to control the level of fishing mortality of these stocks. Overfished stocks with an uncertain fishing mortality status in 2016 are blue warehou, eastern gemfish, gulper sharks, redfish and school shark.

FIGURE 8.2 Fishing mortality status for all stocks assessed in the SESSF, 2004 to 2016
FIGURE 8.3 Biomass status for all stocks assessed in the SESSF, 2004 to 2016

8.5 Economic status

The SESSF HSF provides a framework to assess the economic status of the fishery. Indicators of stock biomass are used to assess the current biomass of species relative to their BMEY target (or its proxy, 1.2BMSY or 0.48B0). When this information is combined with indicators of profitability and efficiency, the economic status of SESSF sectors can be assessed in terms of whether they are moving towards or away from MEY.

Scalefish catches in the CTS and the SHS accounted for 57 per cent of SESSF GVP in 2015–16 (Figure 8.4). These sectors are therefore key drivers of economic performance in the SESSF. Of these two sectors, only the CTS is surveyed as an individual sector by ABARES as part of its fishery economic surveys program; the SHS is surveyed as part of the GHTS. NER for the CTS followed a positive trend from 2004–05 to a peak of $7.4 million in 2010–11. NER declined in 2011–12 and 2012–13, but remained positive. Based on preliminary estimates, NER for the sector declined in 2013–14. This result was probably driven by lower GVP generated in the CTS as a result of declines in beach prices of some key species caught in the sector, including blue grenadier and tiger flathead, and lower volumes landed of tiger flathead.

The estimated biomass for three of the most valuable species within the sector (blue grenadier—Macruronus novaezelandiae, silver warehou—Seriolella punctata, and tiger flathead—Neoplatycephalus richardsoni) remained above or close to the respective BMEY targets (Chapter 9). This indicates that the economic status of the CTS is positive and has improved substantially since 2004–05. However, it could be further improved if adjustment to proxy target reference points were made to better reflect BMEY for some of the more valuable species in the sector.

Historically, orange roughy has contributed substantially to GVP for the CTS. The rebuilding of orange roughy stocks over the longer term should improve the economic status of the sector, although sustainable harvests of this species are likely to be much lower than peak historical levels. The recommencement of fishing for orange roughy in the eastern zone boosted GVP in 2015–16. Likewise, the blue grenadier catch was substantially lower than the TAC in 2014–15 and 2015–16, suggesting that increased catch of this species could increase the GVP of the sector in future seasons.

Economic indicators for the GHTS were used to assess the economic status of the SGSHS, which accounted for 77 per cent of GVP in the GHTS in 2015–16. For the decade preceding 2009–10, estimates of NER in the GHTS had been positive. Estimates became negative in 2009–10 (−$0.44 million in 2015–16 dollars) and have fluctuated below zero since then. This is despite biomass levels of gummy shark (Mustelus antarcticus), the main target species of the sector, being close to or above the target reference point for the stock (Chapter 12). Recent spatial closures aimed at reducing marine mammal interactions in the sector are likely to have contributed to this change, as have school shark controls and the impacts they have on gummy shark catches. A key challenge for the sector is rebuilding the school shark stock, potentially resulting in NER increasing over time. However, the rebuilding of stock is subject to adjustment costs to avoid the species during the rebuilding process.

The development of a bio-economic model for the two key species targeted in the GABTS (deepwater flathead and bight redfish) has improved the ability of fishery managers to target BMEY (Kompas et al. 2012). The most recent stock assessments for bight redfish projected biomass levels at the start of 2014–15 to be above the BMEY target (Haddon 2015), potentially allowing increased profits from the species if it is fished down to its MEY target reference point. The most recent stock assessment for deepwater flathead suggests that biomass has rebuilt towards the BMEY target (Chapter 11). Hence, fishery profitability is unlikely to be constrained by stock status.

In the ECDTS, levels of fishing effort have been low in recent years. Low expected profit in the sector appears to have discouraged activity in the fishery. As a result, the sector has generated minimal NER.

FIGURE 8.4 Real GVP in the SESSF by sector, 2005–06 to 2015–16
Notes: CTS Commonwealth Trawl Sector. GABTS Great Australian Bight Trawl Sector. GVP Gross value of production. SGSHS Shark Gillnet and Shark Hook sectors. SHS Scalefish Hook Sector. GVP for the SGSHS includes only gummy shark, school shark and sawshark, and elephantfish, caught in the gillnet and hook sectors. GVP for other sectors includes non-scalefish product caught in the CTS and the SHS, non-shark product caught in the SGSHS, and product caught in the Victorian Inshore Trawl and East Coast Deepwater Trawl sectors of the SESSF.

Overall, the current economic status of the SESSF is mixed. The negative change in economic performance in the GHTS has occurred at the same time as positive NER in the CTS; meanwhile, the GABTS continues to pursue estimated BMEY targets for its key species. The deterioration in economic performance in the GHTS demonstrates that management of bycatch and other environmental issues (for example, interactions with protected species) can have economic impacts on a fishery, and such factors should be taken into account when assessing the economic performance of the fishery.

The SESSF HSF will continue to make an important contribution to the economic performance of the fishery by guiding management decisions that explicitly aim to maximise NER. The HSF also offers the opportunity to adjust management settings (for example, to re-examine proxy settings where TACs are continually not met or to move the fishery closer to its economic potential).

8.6 Environmental status

General bycatch and discards

Bycatch is defined in the HSP as ‘species taken incidentally in a fishery where other species are the target, and which are always discarded' (DAFF 2007). Tuck et al. (2013) evaluated bycatch and discards (including target and byproduct species) in six Commonwealth fisheries, including the SESSF, and concluded that trawling in the South East Trawl (SET) sector and the GABTS, and Danish-seining account for the greatest volume of bycatch in the Commonwealth fisheries examined. This largely reflects the high level of fishing activity in these sectors and fisheries. Bycatch and discards largely comprise small fish species with little or no commercial value, but also include crustaceans, sharks, molluscs and, more rarely, marine mammals, reptiles and seabirds.

Data collected by the ISMP over 20 years have shown a reduction in the volume of trawl discards since the mid 2000s. A one-third decrease in trawling effort in the SESSF during this time, combined with changes in mesh types and increased mesh sizes used in trawl net codends, probably explains much of the reduction in the volume of discards. Tuck et al. (2013) found that discard rates for quota species have been variable, and dependent on market prices, availability of quota and sporadic influxes of small fish, particularly blue grenadier. However, data for bycatch and discards of rarer commercial species are often lacking, because observer coverage is often focused on key commercial species.

A distinction can be made between highly targeted shots on single-species aggregations (such as orange roughy or blue grenadier) and general shots for multiple species in the SET and GABT sectors of the SESSF. General shots are often referred to as ‘market fishing', and are associated with higher levels of byproduct, and discarding of target and non-target species (Tuck et al. 2013). ISMP data show that up to 50 per cent of catch weight is caught and discarded in the ‘market fishery' of the SET sector, and 40–60 per cent in the GABTS (Tuck et al. 2013). Commercial species are discarded for various reasons, but most discards are small fish species with little or no commercial value. In comparison, bycatch in more targeted fishing can be extremely low. For example, bycatch levels were less than 1 per cent when orange roughy was targeted in the GABTS.

A key change in the SET sector was setting the minimum codend mesh size at 90 mm; this was introduced in 1965 to reduce the catch of small tiger flathead (Tuck et al. 2013). Studies have shown an escapement rate of around 70 per cent of all species swept into the codend that are able to fit through the mesh, equating to around 30 per cent of the catch weight (Tuck et al. 2013). Animals passing through this mesh size were mainly small finfish. Other changes that have helped reduce bycatch in both the SET sector and the GABTS include the use of ‘T-90 panels' or ‘T-90 lengtheners'. Trials of mesh size and type led to mandatory requirements for bycatch reduction in the SET sector in 2006 and the GABTS in 2007. Tuck et al. (2013) reported that the level of bycatch reduction achieved through these measures has not been formally tested.

Introduction of new bycatch mitigation measures in the Danish-seine component of the fishery has been limited, despite trials showing that a change from 75 mm mesh to T-90 in codends did not affect the catch weight of targeted species but reduced the catch weight of non-commercial species by around 27 per cent (across the study). Reasons for the lack of uptake include limited spatial and temporal coverage of the trials, and concern from industry about the use of the T-90 codend at certain times of the year (Tuck et al. 2013).

In the GHTS, which includes the SGSHS, discarding of target species is minimal, with 2 per cent of teleosts and 3 per cent of chondrichthyans discarded (Walker et al. 2005). Trials to estimate discards for non-target species have reported that discards can account for more than 30 per cent of catch weight in commercial nets (6 inch mesh—that is, 15 cm or 150 mm). The most commonly discarded species were draughtboard shark (Cephaloscyllium laticeps), Port Jackson shark (Heterodontus portusjacksoni) and spikey dogfish (Squalus megalops). Discards in the trials increased to 40 per cent, on average, for 5 inch mesh (127 mm) and almost 80 per cent for 4 inch mesh (101.6 mm) (Braccini et al. 2009).

Trawling impacts

Pitcher et al. (2015) used modelling to quantify and assess cumulative threats, risks to benthic biodiversity and the effects of management actions in the south-east marine region, which covers a large part of the SESSF management zone. The research indicated that, from around 1985, when consistent logbook records were available, all 10 benthic taxa types declined in abundance in trawled areas until the mid 2000s. Around this time, fishing effort decreased as a result of economic conditions and the Securing our Fishing Future structural adjustment package, and large areas were closed to trawling.

The lowest total regional abundance of benthic taxa types across the south-east marine region was around 80–93 per cent of pre-trawl abundance after the peak in fishing effort between 2000 and 2005. After this time, all taxa were predicted to recover by between 1 and 3 per cent in the following decade.

The research indicated that the reduction in fishing effort was the main factor influencing the magnitude of recovery. In some cases, spatial management that excluded trawling led to improved abundance of some benthic taxa types. Most fishery closures and Commonwealth marine reserves had little detectable influence on abundance. In other cases, closures reduced the abundance of some taxa in some areas because trawling was displaced to areas where such taxa were more abundant (Pitcher et al. 2015).

Protected species

The SESSF interacts with various species listed as protected or conservation dependent under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). Six former target species in the SESSF are listed as conservation dependent: orange roughy, eastern gemfish, Harrisson's dogfish (Centrophorus harrissoni), southern dogfish (C. zeehaani), school shark and, most recently, blue warehou. These species, discussed in Chapters 9 and 12, are under rebuilding or recovery strategies. They are currently managed under incidental catch allowances, closed areas and trip limits, to allow for incidental catch when fishers are targeting other species.

Recent reductions in interactions with protected species have been observed, to varying degrees. However, the reductions are difficult to attribute to recent measures to mitigate catch of protected species because of a lack of data. These measures have included fishery closures to protect Australian sea lions (Neophoca cinerea) and gulper sharks; seabird mitigation measures for longline and trawl fisheries; seal, turtle and other bycatch excluder devices; and gear modifications (Tuck et al. 2013). Trends in interactions with protected species are also difficult to interpret with confidence because the ISMP was originally designed only to provide estimates of the retained and discarded proportions of fish catch in the SESSF. A review of the ISMP in 2009 sought to facilitate better estimates of protected species interactions and bycatch of major non-quota species.

Fishers are required to take all reasonable steps to avoid interactions with protected species (other than those listed as ‘conservation dependent') and are required to report all interactions in their logbooks. An interaction is defined as any physical contact that a person, boat or gear has with a protected species, including catching and colliding with any of these species. Every three months, AFMA reports all interactions with protected species recorded in logbooks to the Australian Government Department of the Environment and Energy. These reports (which are published on the AFMA website) provide the basis for reports of the number of interactions with protected species within the SESSF in 2016. Interactions are known to occur with species groups protected under the EPBC Act, including marine mammals (cetaceans and pinnipeds), seabirds, sharks (white shark—Carcharodon carcharias, grey nurse shark—Carcharias taurus, shortfin mako shark—Isurus oxyrinchus, porbeagle shark—Lamna nasus) and syngnathids (seahorses and pipefish). Although these interactions are rare, they can have a significant impact on some species that have small populations. However, it is difficult to obtain robust estimates of total interactions or interaction rates at low levels of observer coverage or monitoring, especially when such interactions are rare. The introduction of electronic monitoring of all fishing activity in the GHTS is expected to improve estimates of interactions with protected species.

Pinnipeds (seals and sea lions)

The areas fished by the SESSF overlap with the distributions of the Australian fur seal (Arctocephalus pusillus doriferus), New Zealand fur seal (A. forsteri), Antarctic fur seal (A.gazella) and Australian sea lion. Fur seal populations have recovered substantially following heavy harvesting in the 18th and 19th centuries, but sea lions are currently listed under the EPBC Act as vulnerable. The CTS and Shark Gillnet Sector, in particular, are known to interact with these species, whereas interactions with the hook sectors are much rarer. Between 1993 and 2000, data collected by the ISMP and its precursor (the Scientific Monitoring Program) indicated that an average of 720 fur seals might be caught incidentally by small trawlers operating in the CTS each year (Knuckey et al. 2002). Because of their smaller vessel size and net sizes, wet-boat trawlers have reduced ability to apply mitigation methods such as seal excluder devices (SEDs), which are designed for larger nets. Trials of a flexible SED design suitable for use in smaller nets have been reasonably successful (Knuckey 2009), but reliably estimating and reducing the level of interactions between seals and wet-boats remain difficult. A trial using a shortened codend to reduce seal bycatch was completed in late 2014. The trial found no definitive proof that short trawl nets had lower interaction rates with seals, caught fewer seals or resulted in lower mortality rates of caught seals (Koopman et al. 2014).

Minimising seal interactions has been a focus for the winter trawl fishery for blue grenadier off western Tasmania. SEDs have been compulsory for freezer boats in this component of the SESSF since 2005, and modifications to fishing practices seem to have substantially reduced the incidence of seal bycatch in the midwater nets of factory vessels. Observers have been deployed on factory trawlers to verify interaction rates. In 2007, the South East Trawl Fishing Industry Association (SETFIA) released an updated trawl industry code of conduct for responsible fishing. It also released an industry code of practice that aims to minimise interactions with fur seals, as well as addressing the environmental impacts of the fishery more generally.

The Australian sea lion is endemic and listed as vulnerable under the EPBC Act. Sea lion populations were reduced substantially by sealing between the 18th and early 20th centuries, and recovery has been slow (DEWHA 2010). Australian sea lions show high genetic differentiation because of the high fidelity of female sea lions to their natal sites, indicating that animals lost from a colony are unlikely to be replaced by immigrants from other colonies (DEWHA 2010). The small size of some colonies suggests that the loss of a few breeding females from a population can significantly reduce the long-term recovery prospects of that population (Goldsworthy et al. 2010).

In 2003, closures were introduced around the Pages Islands (the largest sea lion colony) and around Kangaroo Island in South Australia. In December 2009, interim voluntary closures of 4 nautical miles were introduced around all colonies. The current declaration of the SESSF as an approved Wildlife Trade Operation under the EPBC Act includes a requirement to implement long-term management measures, including formal fisheries closures, which should significantly reduce the impact of fishing on Australian sea lions and facilitate the recovery of subpopulations.

There have been concerns about the mortality of Australian sea lions caught as bycatch in shark gillnets. However, implementation of the Australian sea lion management strategy (AFMA 2010) reduced sea lion interactions in gillnets to close to zero. Measures taken by AFMA included spatial closures around colonies, increased observer coverage and trigger limits, with observed levels of bycatch above the trigger limits resulting in the closure of larger areas (AFMA 2010).

AFMA lowered the trigger limit for sea lion mortalities in December 2011, following advice from marine mammal experts regarding risks to some sea lion subcolonies. The trigger limit was reduced from 52 animals to 15 animals across seven management zones in the Australian sea lion management area (AFMA 2011a). There were two sea lion mortalities in the gillnet sector in the 2015–16 fishing season. As a result, Zone C, which is in waters off South Australia, was closed on 14 January 2016 because the trigger limit for mortalities for Australian sea lions for that zone was reached. This closure remained in place until 18 June 2017.

Increased onboard observer coverage or camera monitoring has obtained reliable data on interaction rates, and it is important that this monitoring continues. In the first six months of the sea lion management strategy, the prescribed level of observer coverage was not achieved. Consequently, the Australian Government funded a trial of onboard cameras to monitor Australian sea lion bycatch in 2010–11. In 2011, an expert review of the management strategy resulted in AFMA introducing a Temporary Order (six months, effective 1 May) that increased the size of closed areas around 31 colonies and required 100 per cent observer coverage on gillnet vessels off South Australia in the Australian sea lion management area. This area consists of several zones, each with an interaction limit that triggers closure of the zone if the limit is reached. Onboard cameras have been deployed in the fishery and are used instead of a scientific observer. The Temporary Order was replaced by a Closure Direction, which extended protection to 50 known Australian sea lion colonies. The existing closures around Australian sea lion colonies will be retained, and were incorporated into the permanent Closure Direction for the SESSF from the beginning of the 2015–16 fishing season. Observer requirements in the Australian sea lion management area off South Australia, including 100 per cent onboard observers or electronic monitoring, have been continued under conditions attached to permits and statutory fishing rights.

In 2016, 136 pinniped interactions were reported in CTS and GHTS logbooks: 18 with Antarctic fur seals, 2 with Australian sea lions, 6 with New Zealand fur seals, 71 with Australian fur seals and 39 with seals of unknown species. This is a slight increase from the 134 interactions reported in 2015. Of the 136 reported pinniped interactions, 14 of the Antarctic fur seals, 1 Australian sea lion, 5 of the 6 New Zealand fur seals, 65 of the 71 Australian fur seals and 33 of the 39 unspecified seals were reported to be dead.

In the CTS, 89 per cent of all pinniped interactions in 2016 were reported from bottom-trawling operations, and the remainder of interactions (11 per cent) were reported from Danish-seine or midwater trawl operations. Of the pinniped interactions reported in logbooks in the GHTS in 2016, 97 per cent were reported from gillnet operations.

Fishing vessel
Ryan Keightley, AFMA

Dolphins

All cetaceans are protected species under the EPBC Act. Increased observer coverage in the SGSHS in 2011 highlighted interactions with dolphins and potential under-reporting in logbooks (AFMA 2011a). Two dolphin mortalities were reported in logbooks between January and September 2010 (AFMA 2011b), and 52 interactions with dolphins were reported from September 2010 to September 2011 (AFMA 2011b). In response, AFMA closed to gillnet fishing an area of about 27,239 km2 south-west of Kangaroo Island, where most of the interactions had been reported (dolphin gillnet closure). Observer coverage was increased to 100 per cent (onboard observer or camera) in the area adjacent to the dolphin gillnet closure, and 10 per cent onboard observer coverage was required across the eastern part of the fishery in Bass Strait and around Tasmania.

In 2014, AFMA worked with experts in the marine mammal working group and the fishing industry to implement the first stage of a dolphin management strategy. The objectives of the dolphin strategy are to reduce dolphin interactions in gillnets to near zero, and strengthen responsible fishing practices through electronic monitoring and individual accountability. On 8 September 2015, AFMA reopened the dolphin gillnet closure to limited gillnet fishing, with 100 per cent electronic monitoring and individual boat-level performance standards. Under the dolphin strategy, fishers that do not have interactions with dolphins may continue fishing responsibly. However, there are now management responses for any dolphin bycatch in the gillnet fishery, and individual operators fishing in the former dolphin gillnet closure (Coorong Dolphin Zone) incur escalating management responses if they catch dolphins. This culminates in a six-month closure to gillnet fishing in the Coorong Dolphin Zone if fishers exceed performance standards specified in the dolphin strategy.

In 2016, interactions were reported with 37 dolphins in the GHTS, 34 of which were reported to be dead, and 1 interaction was reported in the CTS, and the dolphin was dead. This is an increase from the 29 interactions reported in 2015 and is likely to reflect the introduction of electronic monitoring in the GHTS.

Seabirds

In 1998, in accordance with EPBC Act requirements, the Australian Government developed a threat abatement plan for the incidental bycatch of seabirds during oceanic longline fishing operations. The plan, which was revised in 2006 and in 2014 (Department of the Environment 2014), applies to longline operations in all Commonwealth fisheries, including the SESSF, and is the main guide to mitigating seabird bycatch in this sector. The levels of seabird bycatch recorded by auto-longline, demersal longline, dropline and trotline operators in the SESSF are low compared with those in other pelagic longline fisheries that target tuna and billfish (Brothers 1991; Brothers et al. 2010; CCAMLR 2002).

Seabirds also interact with trawling activities—they are vulnerable to injury as a result of striking the trawl warps (the trawling cables) during fishing operations, predominantly when catches are being processed and offal is discarded into the water. Analysis of observer data suggests that the number of interactions may be high, but further work is needed to understand their scale and significance (Phillips et al. 2010). Given the difficulty in documenting these interactions (birds suffering warp strike are not landed and are not easily observed), obtaining reliable estimates of seabird mortalities is difficult, even with onboard observers. The issue was investigated by a research project between AFMA and the Tasmanian Department of Primary Industries, Parks, Water and Environment. Mitigation measures, such as offal management and bird-scaring devices, have been effective in reducing seabird bycatch elsewhere. During 2011, AFMA worked with SETFIA to develop tailored seabird management plans for individual vessels, to address this issue.

As part of their boat-specific seabird management plans, vessels are required to use effective seabird mitigation devices. In late 2014, AFMA completed a trial using observers to test the effect of seabird mitigation devices on seabird interactions with otter trawlers. The trial showed that the use of warp deflectors (large floats attached in front of trawl warps to scare birds away—often called ‘pinkies') reduced heavy contact between actively feeding seabirds and warp wires by around 75 per cent (Pierre et al. 2014). Based on the outcomes of the trial, AFMA mandated a minimum requirement in seabird management plans of 600 mm pinkies. SETFIA has also introduced a code of conduct and training program to improve seabird avoidance measures, and undertook a trial of alternative seabird mitigation devices, including water sprayers and bird bafflers. SETFIA reported that water sprayers and bird bafflers used in the trial reduced interactions between seabirds and the warp by 90 per cent and 96 per cent, respectively.

Seabird interactions are probably under-reported for numerous reasons, including that it may be difficult to constantly observe seabirds interacting with fishing gear and vessels, and that seabirds may not have visible injury after interactions such as warp strikes. During 2016, 164 seabird interactions were reported in logbooks or by observers in the SESSF: 143 in the GHTS, 20 in the CTS and 1 in the GABTS. This is an increase from 49 seabird interactions reported in 2014. Of the 164 interactions, most were with the following groups: 77 were reported as unclassified petrels, prions and shearwaters, 76 of which were reported to be dead; 9 were with little penguins (Eudyptula minor), 3 of which were dead; 7 were with white-chinned petrels (Procellaria aequinoctialis), 4 of which were reported to be dead; 4 were with shy albatross (Thalassarche cauta), all of which were released alive; 19 were with unclassified albatrosses, 7 of which were reported to be dead; 11 were with cormorants, all of which were dead; 8 were with flesh-footed shearwaters (Ardenna carneipes), all of which were dead; 11 were with unclassified shearwaters, 10 of which were dead; and 6 were with unidentified seabirds, 5 of which were dead. The remaining interactions were with black-browed albatross (T. melanophris), Wilson's storm petrels (Oceanites oceanicus), Pacific gulls (Larus pacificus), white-faced storm petrels (Pelagodroma marina), fairy prions (Pachyptila turtur), Australian gannets (Morus serrator), Buller's albatross (T. bulleri) and grey-headed albatross (T. chrysostoma).

Sharks

In 2016, 132 interactions with protected sharks were reported in logbooks: 130 in the GHTS (102 of which were dead) and 2 in the CTS (1 of which was dead). The most prevalent shark was shortfin mako, with 102 interactions reported, 90 of which were reported to be dead. Twelve white sharks were reported—11 in the GHTS; 10 were released alive, 1 was reported to be dead and 1 was in unknown condition. Seventeen porbeagle sharks were reported, of which 11 were dead and 6 were injured; and 1 grey nurse shark was reported in the GHTS, which was reported to be dead. The EPBC Act requires all white sharks and grey nurse sharks to be released alive, if possible.

During 2012, in view of their overfished status, a proposal was made to list Harrisson's dogfish and southern dogfish as threatened species under the EPBC Act. On 30 May 2013, the then Minister for Sustainability, Environment, Water, Population and Communities decided to list Harrisson's dogfish and southern dogfish in the conservation dependent category, noting that both species have experienced severe historical declines after being overfished. These species are subject to recovery plans that specify management actions to stop their decline and support their recovery.

Syngnathids (seahorses and pipefish)

Syngnathids are taken as bycatch in the CTS in otter-trawl and Danish-seine nets, but they are often small and difficult to observe among large catches of fish. No interactions with syngnathids were reported in 2016, although one was captured in the GABTS and was noted to be dead.

8.7 References

AFMA 2010, Australian sea lion management strategy: Southern and Eastern Scalefish and Shark Fishery (SESSF), Australian Fisheries Management Authority, Canberra.

—— 2011a, Fisheries Management (Southern and Eastern Scalefish and Shark Fishery Management Plan 2003) Temporary Order 2011, AFMA, Canberra.

—— 2011b, Fisheries Management (Southern and Eastern Scalefish and Shark Fishery Management Plan 2003) Temporary Order 2011 no. 2, AFMA, Canberra.

—— 2014, Harvest strategy framework for the Southern and Eastern Scalefish and Shark Fishery, 2009 (amended February 2014), AFMA, Canberra.

—— 2016, Southern and Eastern Scalefish and Shark Fishery: management arrangements booklet 2016, AFMA, Canberra.

Braccini, J, Walker, T & Gason, A 2009, GHATF shark survey of population abundance and population size composition for target, byproduct and bycatch species, final report to AFMA, project 2006/823, Department of Primary Industries, Queenscliff.

Brothers, N 1991, ‘Albatross mortality and associated bait loss in the Japanese longline fishery in the Southern Ocean', Biological Conservation, vol. 55, pp. 255–68.

——, Duckworth, AR, Safina, C & Gilman, EL 2010, ‘Seabird bycatch in pelagic longline fisheries is grossly underestimated when using only haul data', PLoS ONE, vol. 5, no. 8, e12491.doi:10.1371/journal.pone.0012491.

CCAMLR 2002, ‘Incidental mortality arising from longline fishing', in Report of the twenty-first meeting of the Scientific Committee of the Commission for the Conservation of Antarctic Marine Living Resources, Commission for the Conservation of Antarctic Marine Living Resources, Hobart, pp. 288–331.

DAFF 2007, Commonwealth Fisheries Harvest Strategy: policy and guidelines, Australian Government Department of Agriculture, Fisheries and Forestry, Canberra.

Department of the Environment 2014, Threat abatement plan 2014 for the incidental catch (or bycatch) of seabirds during oceanic longline fishing operations, Australian Government Department of the Environment, Canberra.

DEWHA 2010, Recovery plan for the Australian sea lion (Neophoca cinerea),technical issues paper, Australian Government Department of the Environment, Water, Heritage and the Arts, Canberra.

Fay, G, Punt, AE & Smith, ADM 2009, ‘Operating model specifications', in SE Wayte (ed.), Evaluation of new harvest strategies for SESSF species, CSIRO Marine and Atmospheric Research and AFMA, Canberra, pp. 125–33.

George, D & New, R 2013, Australian fisheries surveys report 2012: financial and economic performance of the Eastern Tuna and Billfish Fishery, the Commonwealth Trawl Sector and the Gillnet, Hook and Trap Sector, ABARES, Canberra.

Goldsworthy, SD, Page, B, Shaughnessy, PD & Linnane, A 2010, Mitigating seal interactions in the SRLF and the Gillnet Sector SESSF in South Australia, report to Fisheries Research and Development Corporation, South Australian Research and Development Institute, Research Report Series 405, SARDI Aquatic Sciences, Adelaide.

Haddon, M 2015, Bight redfish (Centroberyx gerrardi) stock assessment using data to 2014/2015, draft report, CSIRO Oceans and Atmosphere, Hobart.

——, Klaer, N, Wayte, S, & Tuck, G 2015, Options for tier 5 approaches in the SESSF and identification of when data support for harvest strategies are inappropriate, report to FRDC, CSIRO, FRDC final report 2013/200, CSIRO Oceans and Atmosphere, Hobart.

——, Klaer, N & Tuck, G 2016, Development of robust methods to estimate acceptable levels of incidental catches of different commercial and by-product species, report to FRDC, CSIRO, FRDC final report 2011/028, CSIRO Oceans and Atmosphere, Hobart.

Knuckey, IA 2009, Trials of seal excluder devices (SEDs) on a South East Trawl Fishery wet boat, final report to the Natural Heritage Trust.

——, Eayrs, S & Bosschietter, B 2002, Options for reducing incidental catch of seals on wet-boats in the SETF: a preliminary report, final report to AFMA, ARF project R01/0887, Marine and Freshwater Resources Institute, Queenscliff.

Kompas, T, Che, N, Chu, L & Klaer, N 2012, Transition to MEY goals for the Great Australian Bight Trawl Fishery, report to FRDC, Australian Centre for Biosecurity and Environmental Economics, Crawford School of Public Policy, Australian National University, Canberra.

Koopman, M, Boag, S & Knuckey, I 2014, Assessment of potential mitigation of seal interactions in the SESSF using shortened cod ends, AFMA project 2012/0828, Fishwell Consulting.

Little, LR, Wayte, SE, Tuck, GN, Smith, ADM, Klaer, N, Haddon, M, Punt, AE, Thomson, R, Day, J & Fuller, M 2011, ‘Development and evaluation of a CPUE-based harvest control rule for the Southern and Eastern Scalefish and Shark Fishery of Australia' ICES Journal of Marine Science, vol. 68, no. 8, pp. 1699–05, doi:10.1093/icesjms/fsr019.

Pascoe, S, Hutton, T, Thebaud, O, Deng, R, Klaer, N & Vieira, S 2015, Setting economic target reference points for multiple species in mixed fisheries, FRDC project 2011/200, CSIRO Oceans and Atmosphere Flagship, Brisbane.

Phillips, K, Giannini, F, Lawrence, E & Bensley, N 2010, Cumulative assessment of the catch of non-target species in Commonwealth fisheries: a scoping study, Bureau of Rural Sciences, Canberra.

Pierre, J, Gerner, M & Penrose, L 2014, Assessing the effectiveness of seabird mitigation devices in the trawl sectors of the Southern and Eastern Scalefish and Shark Fishery in Australia, AFMA, Canberra.

Pitcher, C, Ellis, N, Althaus, F, Williams, A & McLeod, I 2015, ‘Predicting benthic impacts and recovery to support biodiversity management in the South East Marine Region', in N Bax & P Hedge (eds), Marine Biodiversity Hub, National Environmental Research Program, final report 2011–2015, report to the Australian Government Department of the Environment, Canberra.

SEMAC 2014, ‘South East Management Advisory Committee (SEMAC) meeting minutes', meeting 14, 31 January 2014, AFMA, Canberra.

Tuck, GN, Knuckey, I & Klaer, NL 2013, Informing the review of the Commonwealth Policy on Fisheries Bycatch through assessing trends in bycatch of key Commonwealth fisheries, FRDC final report 2012/046, FRDC, Canberra.

Walker, P, Cavanagh, R, Ducrocq, M & Fowler, S 2005, ‘Regional overview: northeast Atlantic (including Mediterranean and Black Sea)', in International Union for Conservation of Nature (IUCN) SSC Shark Specialist Group, S Fowler, R Cavanagh, M Camhi, G Burgess, G Cailliet, S Fordham, C Simpfendorfer & J Musick (eds), Sharks, rays and chimaeras: the status of the chondrichthyan fishes, IUCN, Gland, Switzerland, & Cambridge, United Kingdom, pp. 71–95.

Ward, P, Marton, N, Moore, A, Patterson, H, Penney, A, Sahlqvist, P, Skirtun, M, Stephan, M, Vieira, S & Woodhams, J 2013, Technical reviews for the Commonwealth Fisheries Harvest Strategy Policy: implementation issues, report prepared for FRDC, ABARES, Canberra.

Wayte, SE (ed.) 2009, Evaluation of new harvest strategies for SESSF species, CSIRO Marine and Atmospheric Research and AFMA, Canberra.

Footnotes

1The Slope Resource Assessment Group and the Shelf Resource Assessment Group were amalgamated in 2016 to form the South East Resource Assessment Group.

Chapter 9: Commonwealth Trawl and Scalefish Hook sectors

F Helidoniotis, A Koduah, A Moore, N Mazloumi and S Nicol

FIGURE 9.1 Relative fishing intensity (a) in the Commonwealth Trawl Sector and (b) by Danish-seine operations, 2016–17 fishing season

(a) in the Commonwealth Trawl Sector

(b) by Danish-seine operations


FIGURE 9.2 Relative fishing intensity in the Scalefish Hook Sector, 2016–17 fishing season

Fishing vessel
Andrew Sampaklis, ABARES
TABLE 9.1 Status of the Commonwealth Trawl and Scalefish Hook sectors
Status
Biological status
2015
Fishing mortality
2015
Biomass
2016
Fishing mortality
2016
Biomass
Comments
Blue-eye trevalla (Hyperoglyphe antarctica)Not subject to overfishing Not overfished Not subject to overfishing Not overfished CPUE is between the limit and target reference points. Fishing mortality is below the most recent RBC.
Blue grenadier (Macruronus novaezelandiae)Not subject to overfishing Not overfished Not subject to overfishing Not overfished Estimated spawning biomass was above target in 2012. Total removals have remained below the long-term RBC.
Blue warehou (Seriolella brama)UncertainOverfishedUncertain OverfishedTotal removals are below the incidental catch allowance. There is no evidence that the stock is rebuilding.
Deepwater sharks, eastern zone (multiple species)Not subject to overfishing UncertainNot subject to overfishing UncertainSubstantial areas where historical catch was taken are closed, and less than 50% of the TAC was caught. Multispecies nature of stock makes CPUE potentially unreliable as the index of abundance.
Deepwater sharks, western zone (multiple species)Not subject to overfishing UncertainNot subject to overfishing UncertainSubstantial areas where historical catch was taken are closed, and less than 50% of the TAC was caught. Multispecies nature of stock makes CPUE potentially unreliable as the index of abundance.
Eastern school whiting (Sillago flindersi)Not subject to overfishing Not overfished Not subject to overfishing Not overfished 2009 estimate of biomass is above the target reference point, but is becoming increasingly uncertain because of its age. Total removals since 2009 have been below the long-term RBC.
Flathead (Neoplatycephalus richardsoni and 4 other species)Not subject to overfishing Not overfished Not subject to overfishing Not overfished Recent estimates of biomass are above the target reference point, and current catches are below the RBC.
Gemfish, eastern zone (Rexea solandri)Uncertain OverfishedUncertain OverfishedBiomass is below the limit reference point. Uncertainty remains around total fishing mortality and rebuilding to the limit reference point within the specified time frame.
Gemfish, western zone (Rexea solandri)Not subject to overfishing Not overfished Not subject to overfishing Not overfished Estimated spawning biomass is above the target reference point. Catches have been stable in recent years and below the RBC.
Gulper sharks (Centrophorus harrissoni, C. moluccensis, C. zeehaani)Uncertain OverfishedUncertain OverfishedPopulations are below the limit reference point, and fishing mortality is uncertain, despite low landed catch and protection from closures.
Jackass morwong (Nemadactylus macropterus)Not subject to overfishing Not overfished Not subject to overfishing Not overfished Estimates of spawning biomass are above the limit reference point. Total removals remain below the RBC.
John dory (Zeus faber)Not subject to overfishing Not overfished Not subject to overfishing Not overfished Catches and fishing mortality rates are low. Assessment indicates that biomass is above the limit reference point.
Mirror dory (Zenopsis nebulosa)Not subject to overfishing Not overfished Not subject to overfishing Not overfished Recent CPUE is above the limit reference point. Total mortality is below RBCs for eastern and western stocks.
Ocean jacket (Nelusetta ayraud)Not subject to overfishing Not overfished Not subject to overfishing Not overfished History of stable CPUE, increasing in recent years.
Ocean perch (Helicolenus barathri, H. percoides)Not subject to overfishing Not overfished UncertainNot overfished Recent CPUE (including discards) is above the limit reference point for both species. Total fishing mortality is above the RBC.
Orange roughy, Cascade Plateau (Hoplostethus atlanticus)Not subject to overfishing Not overfished Not subject to overfishing Not overfished Most recent estimate of spawning biomass (2008) is above the target reference point. Catches since the last estimate have been below the RBC.
Orange roughy, eastern zone (Hoplostethus atlanticus)Not subject to overfishing Not overfished Not subject to overfishing Not overfished Most recent stock assessment estimated biomass to be between the limit and target reference points. Fishing mortality has not exceeded TAC.
Orange roughy, southern zone (Hoplostethus atlanticus)Not subject to overfishing OverfishedNot subject to overfishing OverfishedNegligible catches. Closure of most areas deeper than 700 m. No updated stock assessment.
Orange roughy, western zone (Hoplostethus atlanticus)Not subject to overfishing OverfishedNot subject to overfishing OverfishedNegligible catches. Closure of most areas deeper than 700 m. No updated stock assessment.
Smooth oreodory, Cascade Plateau (Pseudocyttus maculatus)Not subject to overfishing Not overfished Not subject to overfishing Not overfished Low recent catches. CPUE is above the target reference point.
Smooth oreodory, non–Cascade Plateau (Pseudocyttus maculatus)Not subject to overfishing Not overfished Not subject to overfishing Not overfished Closure of most areas deeper than 700 m. Recent CPUE is above the target reference point. New tier 5 assessment indicates catch is below levels that would result in depletion.
Other oreodories (Allocyttus niger, Neocyttus rhomboidalis, A. verrucosus, Neocyttus spp.)Not subject to overfishing Not overfished Not subject to overfishing Not overfished Recent CPUE is stable, near the target reference point, and catch is below the RBC. Closure of most areas deeper than 700 m.
Pink ling (Genypterus blacodes)Not subject to overfishing Not overfished Not subject to overfishing Not overfished Fishing mortality for both stocks has not exceeded TAC. Western stock is above target. Biomass of eastern stock is between the limit and target reference points.
Redfish (Centroberyx affinis)UncertainOverfishedUncertainOverfishedBiomass is below the limit reference point. Catch is above the tier 1 and tier 4 RBCs. It is unclear if total removals are above the level that will allow rebuilding.
Ribaldo (Mora moro)Not subject to overfishing Not overfished Not subject to overfishing Not overfished Standardised CPUE has remained stable and above the target reference point. Catches have remained below RBCs.
Royal red prawn (Haliporoides sibogae)Not subject to overfishing Not overfished Not subject to overfishing Not overfished Recent average CPUE is above the limit reference point, and catches have been below the RBC in recent years.
Silver trevally (Pseudocaranx georgianus)Not subject to overfishing Not overfished Not subject to overfishing Not overfished Recent average CPUE is above the target, and recent catches have been below the RBC.
Silver warehou (Seriolella punctata)Not subject to overfishing Not overfished Not subject to overfishing Not overfished Spawning biomass is between the limit and target reference points. Total removals are below the RBC.

Economic status
NER for the CTS were $4.22 million in 2012–13 and $1.82 million in 2013–14 (preliminary). NER have been positive since 2005–06; likely drivers are increased economic productivity and (from 2014 onwards) falls in the price of fuel. Although key species are close to their BMEY targets, improvements in economic status are still possible by rebuilding certain overfished stocks. The disinclination of fishers to fish down blue grenadier stock may suggest that the proxy target is misaligned with the MEY objective, at least in the short term.

Notes: BMEY Biomass at maximum economic yield. CPUE Catch-per-unit-effort. CTS Commonwealth Trawl Sector. MEY Maximum economic yield. Net economic returns. RBC Recommended biological catch. TAC Total allowable catch.

Hauling the net
SETFIA

[expand all]

9.1 Description of the fishery

Area fished

The Commonwealth Trawl Sector (CTS) of the Southern and Eastern Scalefish and Shark Fishery (SESSF) extends from east of Sydney southwards through Bass Strait and around Tasmania to Cape Jervis in South Australia, where it abuts the Great Australian Bight Trawl Sector (GABTS; Chapter 11; Figure 9.1). To the north, the CTS adjoins the East Coast Deepwater Trawl Sector (Chapter 10) at 24°30'S off Queensland. From the same boundary, the Scalefish Hook Sector (SHS) extends around south-eastern Australia to the border of South Australia and Western Australia (Figure 9.2). The SHS is managed as part of the Gillnet, Hook and Trap Sector (GHTS) of the SESSF, but is reported in this chapter because it shares many target species with the CTS. The CTS and the SHS are major domestic sources of fresh fish for the Sydney and Melbourne markets. In contrast to several Commonwealth fisheries, CTS and SHS landings are rarely exported to overseas markets.

The distribution of many CTS and SHS stocks extends beyond the fishery's boundaries, including into state waters. Under Offshore Constitutional Settlement arrangements, some state jurisdictions have ceded control of SESSF quota-managed species to the Australian Government. In these cases, the catches in state waters by Australian Government–endorsed vessels are debited against their SESSF total allowable catch (TAC) limits. However, New South Wales retains jurisdiction over non-trawl fishers along the New South Wales coastline out to 80 nautical miles (nm) offshore, and over trawl fishers out to 80 nm offshore north of Sydney and out to 3 nm offshore south of Sydney.

Fishing methods and key species

The CTS and the SHS are multigear and multispecies fisheries, targeting a variety of fish and shark stocks using different gear types in different areas or depth ranges. Effort in these fisheries is widely distributed, but, since 2005—after the closure to trawling of most SESSF waters deeper than 700 m—effort has become increasingly concentrated on the shelf rather than on the slope or in deeper waters.

The CTS predominantly involves demersal otter trawl and Danish-seine fishing methods. Pair trawling and midwater trawling methods are also permitted under the SESSF management plan, but are rarely used. The SHS employs a variety of longline and dropline hook fishing methods, some of which are automated.

Management arrangements

Management of the CTS and the SHS follows the SESSF harvest strategy framework (HSF; AFMA 2009a; see Chapter 8), which is based on the Commonwealth Fisheries Harvest Strategy Policy (HSP; DAFF 2007). Both the CTS and the SHS are managed under individual transferable quotas (ITQs) for key commercial species. TACs are set for quota species for each fishing season and allocated to quota holders. All TACs are determined by the Australian Fisheries Management Authority (AFMA) Commission each year. To help reduce assessment and management costs, and create greater certainty for industry, use of multiyear TACs has been increasing since 2009–10. The AFMA Commission determines TACs each year, irrespective of whether stocks are on multiyear TACs. Breakout rules specify the circumstances for reviewing the stock during the multiyear TAC period, and allow for management intervention in the event of unexpected deviation from predicted stock status trends. Twenty-six stocks were on multiyear TACs across the SESSF in 2016–17 (AFMA 2016a), with 19 reported in this chapter.

A total of 20,095 t of quota was allocated in the CTS and the SHS across all quota species or species groups for the 2016–17 fishing season (1 May 2016 to 30 April 2017). This was a decrease of 888 t from 2015–16 (Table 9.2). Most of the 2016–17 quota (19,471 t) was for target species. A further 409 t was allocated as ‘incidental catch allowances' to permit unintentional catches of eastern gemfish (Rexea solandri), blue warehou (Seriolella brama), orange roughy (Hoplostethus atlanticus—southern and western zones1) and redfish (Centroberyx affinis). Most of the overall quota decrease resulted from decreased TACs for silver warehou (Seriolella punctata; –1,208 t), jackass morwong (Nemadactylus macropterus; –124 t), mirror dory (Zenopsis nebulosa; –112 t) and smaller decreases for other stocks. These decreases were partially offset by TAC increases for pink ling (Genypterus blacodes; +164 t), school whiting (Sillago flindersi; +121 t), smooth oreodory non–Cascade Plateau (Pseudocyttus maculatus; +67), gemfish (western zone; +64) and smaller increases for other stocks.

Fishing effort

In 2016–17, trawlers reported around 52,215 hours of fishing effort—a slight decrease from the 54,890 hours in 2015–16 (Figure 9.3; Table 9.2). The number of active trawlers decreased from 37 in 2015–16 to 34 in 2016–17 (Table 9.2). Danish-seine effort decreased from 10,876 shots in 2015–16 to 10,034 shots in 2016–17, and the number of vessels remained constant at 16 in 2015–16 and 2016–17. Fishing effort in the SHS remained relatively constant, at 3.168 million hooks in 2015–16 and 3.192 million in 2016–17 (Figure 9.4; Table 9.2).

Catch

The total landings of all species managed under TACs from the CTS in 2016–17 were 7,634 t. Flathead, blue grenadier, pink ling, eastern school whiting and orange roughy (eastern zone) accounted for approximately 77 per cent of the landed catch. Flathead catches increased from 2,317 t in 2013–14 to 2,908 t in 2015–16, and then decreased to 2,873 t in 2016–17. Catches of blue grenadier decreased from 3,887 t in 2013–14 to 1,306 in 2016–17, representing around 17 per cent of the quota in 2016–17. The large reduction in blue grenadier catch can be attributed to one factory vessel not fishing the winter spawning aggregation since the 2013–14 fishing season. The total scalefish landings from the GHTS (of which the SHS comprises the primary component reported in this chapter) in the 2016–17 fishing season were estimated to be 729 t, slightly higher than the 656 t landed in the 2015–16 fishing season. Total catch for both sectors reported in this chapter (quota stocks and ocean jackets—non-quota stock) was 8,696 in 2016–17; 7,634 t was from CTS quota stocks, 774 t was from GHTS quota stocks and 288 t was from ocean jacket non-quota stocks (ocean jacket includes both ocean jacket and leather jacket). This was slightly below the total of 9,025 t landed in 2015–16. Approximately 42 per cent of quota was landed across the two sectors in 2016–17 (excluding discards).

The term ‘landed catch' refers to the catch that is reported at the port; it excludes discards. Data on discards are collected for the SESSF as part of the Integrated Scientific Monitoring Program. Discard estimates for both the SESSF and state fisheries are presented in Thomson and Upston (2016). The discard data, collected over the previous four years, were converted into a weighted average to estimate discards for the current fishing season (see Table 36 in Thomson & Upston 2016). These estimates are included when reporting on stock status.

The terms ‘agreed TAC' and ‘actual TAC' both refer to the TAC permitted by management. In general, the agreed TAC is estimated by subtracting the discount factor, state catches and discards from the recommended biological catch (RBC) (AFMA 2016b). The actual TAC is the agreed TAC adjusted for any overcaught or undercaught TAC from the previous season.

During 2015–16, scalefish catches in the CTS accounted for 50 per cent of the gross value of production (GVP) in the SESSF. Scalefish GVP in the CTS increased 10 per cent, from $33.53 million in 2014–15 to $36.80 million in 2015–16. The GVP in the SHS increased by 1 per cent, from $4.66 million in 2014–15 to $4.71 million in 2015–16. Overall, the total scalefish GVP in 2015–16 for both sectors was $41.52 million (Table 9.2).

Flathead contributed $18.40 million to GVP in 2015–16, the most of any scalefish (Table 9.2); this was an increase of 16 per cent from $15.64 million in 2014–15. Blue grenadier accounted for $2.24 million, which was 18 per cent higher than in 2014–15 ($1.89 million) but 66 per cent lower than in 2013–14 ($6.66 million). This was the result of lower prices and lower catch. The GVP of pink ling increased slightly (2 per cent), from $4.58 million in 2014–15 to $4.68 million in 2015–16, while the GVP of silver warehou decreased 38 per cent to $0.33 million. The GVP of orange roughy increased 46 per cent to $2.32 million—its highest level in real terms since 2009–10 ($3.46 million).

FIGURE 9.3 Total catch and fishing effort for the CTS, 1985 to 2016
Source: Australian Fisheries Management Authority
FIGURE 9.4 Total catch and fishing effort for the SHS, 2000 to 2016
Source: Australian Fisheries Management Authority
TABLE 9.2 Main features and statistics for the CTS and the GHTS a
Fishery statistics b 2015–16 fishing season2015–16 fishing season2015–16 fishing season2016–17 fishing season2016–17 fishing season
Stock TAC
(t) c
Catch
(t) (CTS, GHTS)
Real value
(2015–16)
TAC
(t) c
Catch
(t) (CTS, GHTS)
Blue-eye trevalla335298 (20, 278) $2.57 million410432 (45, 388)
Blue grenadier8,7961,754 (1 745, 9)$2.24 million8,8101,311 (1,306, 5)
Blue warehou118 d2 (2, <1)$0.11 million118 d16 (16, 0.2)
Deepwater sharks, eastern zone4722 (21, 1)na4725 (24, 0.6)
Deepwater sharks, western zone21568 (67, 1)na21575 (75, 0.5)
Eastern school whiting747733 (733, 0)$2.10 million868718 (717, 0)
Flathead (several species)2,8602,908 (2,908, <1)$18.40 million2,8822,874 (2,873, 1)
Gemfish, eastern zone100 d30 (27, 3)$0.26 million100 d30 (24, 6)
Gemfish, western zone e18381 (76, 5)024773 (70, 4)
Jackass morwong598136 (135, 1)$0.49 million474213 (212, 1)
John dory16986 (86, <1)$0.68 million16782 (82, <1)
Mirror dory437252 (252, 0)$0.79 million325275 (275, <1)
Ocean perch166169 (154, 15)$0.75 million190163 (144, 19)
Orange roughy, Cascade Plateau5002$0 million5000
Orange roughy, eastern zone465436 (436, 0)$1.97 million465363
Orange roughy, southern zone66 f57 (57, 0)$0.19 million66 f43
Orange roughy, western zone60 d22 (22, 0)$0.16 million60 d22
Smooth oreodory, Cascade Plateau1501na1500
Smooth oreodory, non–Cascade Plateau2321 (21, 0)<$0.1 million9048 (47, 0.5)
Other oreodories128141 (140, <1)$0.39 million 128108 (108, <1)
Pink ling980 825 (519, 306)$4.68 million1,144 912 (607, 305)
Redfish100 d49 (49, <1)$0.18 million100 d40 (39, <1)
Ribaldo33590 (54, 36)$0.17 million35588 (49, 39)
Royal red prawn386183 (183, 0)$0.69 million387127 (127, 0)
Silver trevally60272 (72, <1)$0.29 million58853 (52, <1)
Silver warehou2,417276 (275, 1)$0.33 million1,209312 (311, <1)

Fishery statistics b 2015–16 fishing season2015–16 fishing season2015–16 fishing season2016–17 fishing season2016–17 fishing season
Non-quota species TAC
(t)
Catch
(t)
Real value
(2015–16)
TAC
(t)
Catch
(t)
Gulper sharksna<1 (<1, 0)nana0.3 (0.3, 0)
Ocean jacket gna 312$0.52 millionna289
Total 20,983 9,025 $41.52 million 20,095 8,691

Fishery-level statistics 2015–16 fishing season2016–17 fishing season
Effort
Otter trawl
Danish-seine
Scalefish hook
54,890 trawl hours
10,876 shots
3.168 million hooks
52,215 trawl hours
10,034 shots
3.192 million hooks
Boat statutory fishing rights57 trawl; 37 scalefish hook57 trawl; 37 scalefish hook
Active vessels37 trawl; 16 Danish-seine;
18 scalefish hook
34 trawl; 16 Danish-seine;
17 scalefish hook
Observer coverage
CTS
Auto-longline (scalefish)
Trawl: 144 fishing-days
Danish-seine: 20 fishing-days
12 sea-days
Trawl: 129 fishing-days
Danish-seine: 25 fishing-days
0 sea-days h
Fishing methodsTrawl, Danish-seine, hook (dropline, demersal longline), trap (minor)Trawl, Danish-seine, hook (dropline, demersal longline), trap (minor)
Primary landing portsEden, Sydney and Ulladulla (NSW); Hobart (Tas); Lakes Entrance and Portland (Vic) Eden, Sydney and Ulladulla (NSW); Hobart (Tas); Lakes Entrance and Portland (Vic)
Management methodsInput controls: limited entry, gear restrictions, area closures
Output controls: TACs, ITQs, trip limits
Input controls: limited entry, gear restrictions, area closures
Output controls: TACs, ITQs, trip limits
Primary marketsDomestic: Sydney, Melbourne—fresh, frozen
International: minimal
Domestic: Sydney, Melbourne—fresh, frozen
International: minimal
Management plan Southern and Eastern Scalefish and Shark Fishery Management Plan 2003 Southern and Eastern Scalefish and Shark Fishery Management Plan 2003

a The SHS is managed as part of the GHTS. b Fishery statistics are provided by fishing season, unless otherwise indicated. Fishing season is 1 May to 30 April. Real-value statistics are provided by financial year and were not available for the 2016–17 financial year at time of publication. c TACs shown here are the ‘agreed' TACs. These may differ from ‘actual' TACs, which may include undercatch and overcatch from the previous fishing season. Consequently, catch for some stocks may slightly exceed agreed TACs. d Incidental catch allowance. e Not including the Great Australian Bight Trawl Sector. f Total catch includes a 31 t incidental catch allowance and 35 t of target quota, resulting from apportioning quota from the orange roughy eastern zone stock assessment to the Pedra Branca area, which is part of the southern zone but included in the eastern zone assessment. g Catch figures are combined for the trawl and non-trawl sectors. h No human observers deployed in the fishery as electronic monitoring is now mandatory. Video footage of at least 10% of all recorded hauls are reviewed to verify the accuracy of logbooks.
Notes: CTS Commonwealth Trawl Sector. GHTS Gillnet, Hook and Trap Sector. ITQ Individual transferable quota. na Not available. SHS Scalefish Hook Sector. TAC Total allowable catch.

9.2 Biological status

Blue-eye trevalla (Hyperoglyphe antarctica)

Blue-eye trevalla (Hyperoglyphe antarctica) 

Line drawing: FAO

Stock structure

Blue-eye trevalla is managed as a single biological stock in the SESSF (Robinson et al. 2008). Recently, three lines of evidence, based on phenotypic variation in age and growth, otolith chemistry and potential larval dispersal, suggest spatial patterns that may delineate natural subpopulations (Williams et al. 2017). Four geographically distinct subpopulations were identified in the SESSF, with three in the CTS. These three subpopulations are interconnected through regional exchange of larvae (Williams et al. 2017). The results of the study by Williams et al. (2017) have not been implemented into management, and the stock remains as a single biological stock for management purposes.

Catch history

Commonwealth catches have varied in response to changes in the TAC, but in some years there has been uncaught quota. Blue-eye trevalla catch peaked at over 800 t in 1997 (Figure 9.5). Commonwealth landed catch in the 2016–17 fishing season was 432 t. The weighted average discards between 2012 and 2015 were 0.73 t (Thomson & Upston 2016).

FIGURE 9.5 Blue-eye trevalla annual catches (CTS, SHS and states) and fishing season TACs, 1997 to 2016
Note: TAC Total allowable catch. Data for 2016 do not include discards and state catch.
Source: Haddon 2016a; Australian Fisheries Management Authority catch disposal records (2016 data)
Stock assessment

In 2016, data from 1997 to 2015 were used in a tier 4 analysis of blue-eye trevalla (Haddon 2016a). The data included total catches, total discards and standardised catch-per-unit-effort (CPUE). The catch data used were from the CTS (zones 20 to 50 and the eastern seamounts), but excluded catches from the GABTS (zones 84 and 85). The CPUE standardisation included both the CTS (zones 20 to 50) and the GABTS (zones 84 to 85). The CPUE time series was a combination of catch-per-hook from dropline data (1997 to 2006) and auto-longline data (2002 to 2015)(Figure 9.6). The two time series were combined by setting the mean standardised CPUE in the overlapping period (2002 to 2006) to 1.0, to produce a CPUE time series from 1997 to 2015. This combination was used to provide the earliest possible reference period. Despite not including the GABTS catches, the blue-eye trevalla stock is currently assessed and managed as a single stock across the CTS and the GABTS.

There are various sources of uncertainty in the assessment. Two factors may potentially influence catch rates and fishing behaviour, which may result in CPUE being biased low: the presence of killer whales (orcas­—Orcinus orca) near fishing operations, and exclusions from historical fishing grounds following closures implemented to rebuild gulper shark stocks (AFMA 2014a). The 2016 assessment did not detect large effects on catch rates due to the closures; however, there remains uncertainty concerning the effect of whale depredations on CPUE.

The 2016 assessment indicates a decrease in CPUE from 2014 to 2015, although this decrease is within the 95 per cent confidence intervals of the mean estimates. Most of the catch is now caught by only a few vessels; consequently, the CPUE is currently more sensitive to changes in the fishing behaviour of these vessels. This is expected to increase the variance of the CPUE (Haddon 2016b).

FIGURE 9.6 Standardised auto-longline and dropline CPUE index for blue-eye trevalla to the east and west of Tasmania, 1997 to 2015
Note: CPUE Catch-per-unit-effort.
Source: Haddon 2016b
Stock status determination

The estimated four-year average CPUE (2012 to 2015) is between the limit and the target (Figure 9.6), and the blue-eye trevalla stock is therefore classified as not overfished.

For the 2016–17 fishing season, the agreed TAC was 410 t, the actual TAC was 430.121 t and the RBC was 444 t. The catch was 432.91 t, and the weighted average discards were 0.73 t. The catch and discards combined was 433.64 t, which is below the RBC of 444 t. The stock is therefore classified as not subject to overfishing.

Blue grenadier (Macruronus novaezelandiae)

Blue grenadier (Macruronus novaezelandiae) 

Line drawing: Rosalind Poole

Stock structure

Blue grenadier is assessed as a single stock. There are two defined subfisheries: the winter spawning fishery off western Tasmania and the widely spread catches of the non-spawning fishery.

A stock structure study using otolith chemistry and otolith shape (Hamer et al. 2009) has proposed that more than one stock of blue grenadier is fished in the SESSF. Specifically, the otolith indicators provided support for separate stocks of blue grenadier being fished by the GABTS and the CTS of the SESSF. The study also indicated that blue grenadier from the western Tasmanian and eastern Bass Strait regions of the CTS were unlikely to be part of one highly mixed south-eastern Australian stock. However, this stock structure hypothesis has not been adopted by the SESSF Resource Assessment Group (SlopeRAG) and is not used in the stock assessment.

Catch history

The blue grenadier fishery started in the early 1980s, and between 1985 and 1995 mainly targeted non-spawning fish. From 1995 onwards, a fishery developed on spawning aggregations, and total catches increased to average around 8,000 t from 1999 to 2003 (Figure 9.7). Catches since then have varied in response to changes in the TAC and the influence of market conditions. Commonwealth landed catch in the 2016–17 fishing season was 1,311 t. The weighted average discards between 2012 and 2015 were 449 t (Thomson & Upston 2016).

FIGURE 9.7 Blue grenadier annual catches (CTS and SHS) and fishing season TACs, 1979 to 2016
Note: TAC Total allowable catch. Data for 2013 to 2016 do not include discards.
Source: Tuck 2013; Australian Fisheries Management Authority catch disposal records (2013 to 2016 data)
Stock assessment

The tier 1 integrated stock assessment was updated in 2013 (Tuck 2013), incorporating data to the end of 2012, as well as estimates of spawning biomass from industry-based acoustic surveys (2003 to 2010) and egg survey estimates of female spawning biomass (1994 to 1995). Results for the base-case model concluded that the spawning biomass in 2012 was around 77 per cent of the unexploited spawning stock biomass (SB0), and, in 2014, was forecast to be approximately 94 per cent of SB0 (Tuck 2013; Figure 9.8).

Blue grenadier was subject to multiyear TACs of 4,700 t for the 2009–10 to 2011–12 seasons, and 5,208 t for the 2012–13 and 2013–14 seasons. The 2013 assessment estimated a substantially increased three-year RBC of 8,810 t, starting in 2014–15. A 2014–15 TAC of 6,800 t was implemented, after considering industry's preference for a cautious approach to increasing the TAC, to promote economic stability (AFMA 2014b). The multiyear TAC increased to 8,796 t in the 2015–16 season and to 8,810 t in the 2016–17 season.

FIGURE 9.8 Estimated female spawning biomass for blue grenadier, 1973 to 2012
Source: Tuck 2013
Stock status determination

Blue grenadier remains classified as not overfished because the most recent assessment (Tuck 2013) indicated that the spawning biomass was above the target reference point.

For the 2016–17 fishing season, the agreed TAC was 8,810 t, the actual TAC was 9,618 t and the RBC was 8,810 t. The landed catch was 1,312 t, and the weighted average discards were 449.15 t. The landed catch and discards combined was 1,761.15 t, which is below the RBC of 8,810 t. As a result, blue grenadier remains classified as not subject to overfishing.

Blue warehou (Seriolella brama)

Blue warehou (Seriolella brama) 

Line drawing: Rosalind Poole

Stock structure

Blue warehou is assumed to have separate eastern (southern New South Wales to eastern Tasmania) and western (western Tasmania to western Victoria) stocks (Morison et al. 2013). These stocks are assessed separately, but status represents the combined stocks because the TAC is set at this level.

Catch history

Landings of blue warehou peaked in 1991 at 2,478 t (Figure 9.9). Catch has since declined, with less than 500 t landed per year since 2000. A rebuilding strategy that established blue warehou as an incidental catch-only species was first implemented in 2008, with the objective of rebuilding stocks by 2024. Landed catches since then have shown a continued decline, and most recently decreased from 65 t in 2013–14 to 16 t in 2014–15, and to 2 t in 2015–16. However, 6.5 t was reported in logbooks for 2015–16; the reason for the discrepancy is unclear but may reflect misidentification by fishers. Commonwealth landed catch in the 2016–17 fishing season was 16.03 t. The weighted average discards between 2012 and 2015 were 8.68 t (Thomson & Upston 2016).

FIGURE 9.9 Blue warehou annual catches (CTS, SHS and state combined) and fishing season TACs, 1986 to 2016
Notes: TAC Total allowable catch. Data for 2013 to 2016 do not include discards and state catch.
Source: Haddon 2013a; Australian Fisheries Management Authority catch disposal records (2013 to 2016 data)
Stock assessment

Blue warehou has been classified as overfished since 1999 and is currently subject to a stock rebuilding strategy (AFMA 2014c). In February 2015, the species was listed as conservation dependent under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act; Department of the Environment 2015). The stocks are managed under the SESSF tier 4 HSF and assessed using standardised CPUE to determine RBCs. The standardised CPUE series of both the eastern and western blue warehou stocks estimate declines after the 1986 to 1995 reference period (Haddon 2013a). For the eastern stock, CPUE has been below the limit reference point since 1998. For the western stock, CPUE has been below the limit reference point for all years since 1995, except for 1998 and 2005 (Figures 9.10 and 9.11). Under the HSP, RBCs for overfished stocks are zero.

Although each CPUE series is presented as a continuous line, they should be interpreted in two separate periods for each stock (Figures 9.10 and 9.11). The CPUE for the reference period (1986 to 1995) estimates relative abundance when there was no quota management or rebuilding strategy in place. The period after 1995 includes the period of quota-based management measures and, from around 2000 onwards, efforts by the South East Trawl Fishing Industry Association and AFMA to limit targeting. Consequently, CPUE outside the reference period (1986 to 1995) may not be an accurate index of biomass. The ongoing decline in landed catches may reflect one or more factors, including a better ability by fishers to avoid catches, the low incidental bycatch allowances, lower abundance or lower availability. However, there is no evidence to suggest that blue warehou has rebuilt to above the limit reference point.

AFMA set an annual incidental catch allowance of 133 t for blue warehou for 2011–12, which was reduced to 118 t for the 2012–13 and subsequent fishing seasons. The incidental catch allowance includes triggers of 27 t in the east and 91 t in the west. These triggers are intended to alert AFMA and the South East Resource Assessment Group (SERAG) if the ratio of catches in the east and the west change substantially, and result in increased reporting requirements for commercial fishers encountering blue warehou (AFMA 2014c).

The 2008 rebuilding strategy for blue warehou was revised in 2014. It aims to prevent targeted fishing for blue warehou, minimise incidental catches and improve knowledge of stock status, with the goal of rebuilding blue warehou stocks to the limit reference point by or before 2024. In September 2015, the Shelf Resource Assessment Group (ShelfRAG—the precursor to SERAG) discussed whether the rebuilding strategy for blue warehou was meeting its objectives (AFMA 2015a), and noted range contraction and a lack of signs of recovery. It also noted that current SESSF catches, even with low recruitment, should not be impeding recovery.

FIGURE 9.10 Standardised CPUE for blue warehou, western stock, 1986 to 2012
Notes: CPUE Catch-per-unit-effort. CPUE outside the reference period (1986 to 1995) is unlikely to accurately reflect biomass.
Source: Haddon 2013a
FIGURE 9.11 Standardised CPUE for blue warehou, eastern stock, 1986 to 2012
Notes: CPUE Catch-per-unit-effort. CPUE outside the reference period (1986 to 1995) is unlikely to accurately reflect biomass.
Source: Haddon 2013a
Stock status determination

Blue warehou remains classified as overfished because there is no evidence to suggest that the stock has rebuilt to above the limit reference point.

Blue warehou is under a rebuilding strategy. The incidental catch allowance is 118 t. The landed catch for 2016–17 was 16 t, and the weighted average discards were 8.68 t. The catch and discards combined was 24.68 t, which is below the incidental catch allowance of 118 t. The level of fishing mortality that will allow the stock to rebuild is unknown. The stock is therefore classified as uncertain with regard to fishing mortality.

Fishing vessels in port
AFMA

Deepwater sharks, eastern and western zones (multiple species)

Deepwater sharks, eastern and western zones (multiple species) 

Deepwater sharks, eastern and western zones (multiple species) 

Line drawing: FAO and Anne Wakefield

Stock structure

The deepwater shark stock comprises multiple species of deepwater sharks: dogfish (Squalidae), brier shark (Deania calcea), platypus shark (D. quadrispinosa), Plunket's shark (Centroscymnus plunketi), roughskin shark (species of Centroscymnus and Deania), ‘pearl shark' (D. calcea and D. quadrispinosa), black shark (Centroscymnus species), lantern shark (Etmopterus species) and other sharks (Klaer et al. 2014). The black shark is possibly confounded with roughskin and black (roughskin) shark, and Plunket's dogfish is possibly also confounded with the roughskin shark group. The pearl shark group is a combination of the brier and platypus sharks (Haddon 2013a).

Little is known about the stock structure of these deepwater sharks. They are benthopelagic species that have been sampled in oceanic environments over the abyssal plains, and are distributed widely across ocean basins, and along the middle and lower continental shelves. The management boundary between eastern and western deepwater shark quota is the same as that used for gemfish. The eastern area extends from New South Wales, around the Tasmanian east coast and up the Tasmanian west coast to 42°S, including Bass Strait to 146°22'E. The western area includes the remainder of the SESSF, around to Western Australia. This boundary cuts across deepwater shark trawl grounds. The most likely biological boundary for these species is the biogeographical boundary between the two systems dominated by the Eastern Australian Current and the Leeuwin Current off the south coast of Tasmania (Morison et al. 2013).

Catch history

The eastern deepwater shark fishery started in about 1990. Landed catches increased steadily to around 200 t in 1998, with a single higher peak of about 330 t in 1996, before decreasing steadily to around 25 t in recent years (Figure 9.12). The eastern catch in the 2016–17 season was 25 t, below the eastern TAC of 47 t. The western catch followed a similar trend, starting in 1993; it increased to a peak of about 400 t in 1998, before decreasing steadily to less than 10 t in 2007. Catch in the 2016–17 fishing season was 75 t, below the western TAC of 215 t (Figure 9.13).

TACs for the deepwater shark multispecies stock are set separately for the eastern and western areas, and cover all deepwater shark species taken in those areas. In 2016–17, platypus sharks (mixed), roughskin dogfishes (mixed) and sleeper sharks (mixed) accounted for most of the catch in the east; and platypus sharks (mixed), longsnout dogfish and sleeper sharks (mixed) accounted for most of the catch in the west. Discards estimates for deepwater shark were not determined (Thomson & Upston 2016).

FIGURE 9.12 Deepwater shark annual catches (CTS) and fishing season TACs, eastern zone, 1986 to 2016
Notes: TAC Total allowable catch. Data for 2011 to 2016 include catch disposal records from the CTS and the SHS.
Source: Australian Fisheries Management Authority catch disposal records (2011 to 2016 data)
FIGURE 9.13 Deepwater shark annual catches (CTS) and fishing season TACs, western zone, 1986 to 2016
Notes: TAC Total allowable catch. Data from 2011 to 2016 include catch disposal records from the CTS and the SHS.
Source: Australian Fisheries Management Authority catch disposal records (2011 to 2016 data)
Stock assessment

Reliable data on historical catch and discards are lacking. This paucity of data, together with the multispecies nature of the stock and difficulties in species identification by fishers, means that the standardised CPUE series may not be a reliable index of abundance for the individual species or the multispecies stock (Haddon 2013a). In the absence of better data, these stocks are assessed using standardised CPUE under tier 4. Since 2009, the CPUE trend in the eastern zone has been declining, with the recent four-year average being about halfway between the target and limit reference points. SlopeRAG recommended an RBC of 78 t or a multiyear TAC of 47 t, based on the past three years of CPUE. AFMA implemented a three-year multiyear TAC of 47 t for eastern deepwater shark for the 2014–15 to 2016–17 fishing seasons. The recent four-year average CPUE in the west was substantially higher than the target, and SlopeRAG recommended an RBC of 300 t or a TAC of 263 t, based on the past three years of CPUE (AFMA 2013a). Following support for a cautious approach from industry and SlopeRAG, AFMA extended the current TAC into a three-year multiyear TAC of 215 t for western deepwater shark for the 2014–15 to 2016–17 fishing seasons.

Deepwater sharks are mobile animals that cover a broad range of depths (Morison et al. 2013). A significant area of the fishery—around 54 per cent of the area where catch of this stock was previously taken—has been closed as part of the 700 m depth closures to manage orange roughy stocks. These closures offer a significant level of protection to the stock of deepwater sharks, assuming that they are similarly distributed across the open and closed areas. In 2013, a portion of the orange roughy 700 m closed area was reopened under SESSF Closure Direction No. 6 2013 so that deepwater sharks could be fished. The remaining closures still offer substantial protection, justifying the waiving of discount factors in setting multiyear TACs.

Stock status determination

Given the large area closed to fishing (from which historical catch was taken) and the low catches in recent years, the eastern and western deepwater shark stocks are classified as not subject to overfishing. Because deepwater sharks are multispecies stocks, and robust data on historical catch composition and discards are lacking, CPUE is unlikely to provide a reliable index of abundance for these stocks or their component species. As a result, these stocks are classified as uncertain with regard to the level of biomass.

Eastern school whiting (Sillago flindersi)

Eastern school whiting (Sillago flindersi) 

Line drawing: FAO

Stock structure

Eastern school whiting occurs from southern Queensland to western Victoria. Genetic studies have suggested two stocks in this range, with the division between a ‘northern' stock and a ‘southern' stock in the Sydney – Jervis Bay area. However, the evidence for two stocks was weak, and current SESSF management and stock assessment assume a single stock (Morison et al. 2013).

Catch history

Catch of eastern school whiting increased markedly from around 500 t in the mid 1970s to a peak of around 2,500 t in the early 1990s. Commonwealth landed catch in the 2016–17 fishing season was 718 t, taken from the CTS (Figure 9.14). The weighted average discards between 2012 and 2015 were 55.13 t (Thomson & Upston 2016).

FIGURE 9.14 Eastern school whiting annual catches (CTS, SHS and state combined) and fishing season TACs, 1947 to 2016
Notes: TAC Total allowable catch. Data up to 2014 include Commonwealth and state catches and discards; 2015 to 2016 data do not include state catches and discards.
Source: Australian Fisheries Management Authority catch disposal records (2009 to 2016 catch data); CSIRO Integrated Scientific Monitoring Program (2009 to 2014 discard data)
Stock assessment

Estimates of eastern school whiting biomass have varied considerably between successive assessments, largely as a result of the variable and relatively late age of recruitment to the fishery (two to three years) for this short-lived species (with a lifespan of seven years; Day 2012). The most recent full assessment of eastern school whiting was in 2009 (Day 2010), using data up to 31 December 2008. It predicted that the spawning stock biomass would be 50 per cent of the unfished biomass (0.5SB0) in 2010, slightly above the target biomass (0.48SB0) (Figure 9.15). The long-term RBC recommendation at the time was 1,660 t per year. The assessment was updated in 2010 and 2011, using catch, discard, age and length data (Day 2011, 2012). The estimated level of depletion in the updated assessment was approximately 30 per cent of the unfished biomass (0.3SB0; see figure 12.26 in Day 2012).

Day (2012) reported on stock status projections under a range of alternative levels of fixed catch over an 18-year projection period. With a constant catch of 1,700 t per year, the probability of the spawning stock biomass falling below the 0.2SB0 limit reference point was estimated to be less than 10 per cent for the base-case model (Day 2012). After taking the uncertainty around biomass estimates into account, ShelfRAG recommended a long-term RBC of 1,660 t for 2013–14 onwards (AFMA 2014d).

Historically, most of the total catch of eastern school whiting has come from New South Wales state waters. In recent years, the catch in these waters has decreased from historical levels of approximately 1,000 t per year to around 400 t. ShelfRAG has expressed concern that biological and fishery information for eastern school whiting has been collected from a relatively small area of the fishery (primarily from the Lakes Entrance Danish-seine fleet) and may not be representative of the species distribution that extends from Queensland to western Victoria. Given these concerns and the variability in model estimates of biomass for eastern school whiting, there is ongoing work on characterising the available school whiting data and proposed stock assessment structure to support a new assessment in the future.

FIGURE 9.15 Spawning stock biomass for eastern school whiting, 1945 to 2008
Source: Day 2010
Stock status determination

The most recent full assessment (Day 2010) forecasted spawning stock biomass to be approximately 50 per cent of the unfished level at the beginning of 2010, which is above the target reference point. The updates of this assessment with more recent data estimated levels of biomass depletion at approximately 30 per cent (Day 2012). Standardised CPUE to 2015 (Sporcic & Haddon 2016), and size and age composition data from observers and port sampling (Thomson et al. 2016) do not indicate any concerning trends for stock status. As a result, school whiting is classified as not overfished.

For the 2016–17 fishing season, the agreed TAC was 868 t, the actual TAC was 911.2 t and the RBC was 1,660 t. Total landed catch was 717.7 t, and the weighted average discards were 55.13 t. The landed catch and discards combined was 772.83 t, which is below the RBC of 1,660 t. The stock is therefore classified as not subject to overfishing.

Flathead (Neoplatycephalus richardsoni and four other species)

Flathead (Neoplatycephalus richardsoni and four other species) 

Line drawing: Rosalind Poole

Stock structure

For SESSF management purposes, ‘flathead' refers to a group of species. However, the catch is almost entirely tiger flathead (Neoplatycephalus richardsoni). It includes sand flathead (Platycephalus bassensis) and, from 1996 onwards, southern or ‘yank' flathead (P.speculator), bluespot flathead (P.caeruleopunctatus) and gold-spot or toothy flathead (N.aurimaculatus). Tiger flathead is the only species currently assessed in stock assessments.

Tiger flathead is endemic to Australia. It is found on sandy or muddy substrates in continental-shelf and upper-slope waters from Coffs Harbour in northern New South Wales through Bass Strait and around Tasmania to south-east South Australia. Most of the Australian commercial catch comes from depths between 50 and 200 m. The stock structure of tiger flathead is poorly understood. There is some evidence of morphological variation across the distribution range, with observed regional differences in growth, appearance and the timing of reproduction, especially off eastern Tasmania. No stock identification studies using genetic or other techniques have been undertaken. For assessment and management purposes, a single stock has been assumed throughout all zones of the SESSF.

Catch history

Flathead catch has been historically variable, generally fluctuating between 1,500 and 4,000 t per year (Figure 9.16). Catch in recent decades has been relatively stable at approximately 3,000 t (Figure 9.16). The Commonwealth landed catch of flathead in the 2016–17 fishing season was 2,875 t, taken almost fully from the CTS (Table 9.2). The weighted average discards between 2012 and 2015 were 225.18 t (Thomson & Upston 2016).

FIGURE 9.16 Flathead annual catches (CTS and state combined) and fishing season TACs, 1915 to 2016
Notes: TAC Total allowable catch. Data for 2016 do not include discards and state catch.
Source: Day & Klaer 2013; Australian Fisheries Management Authority catch disposal records (2013 to 2016 data)
Stock assessment

The flathead assessment is based on biological parameters relating to tiger flathead, which accounts for about 95 per cent of the flathead catch (Morison et al. 2013). However, the assessment and TAC include catches of all flathead species because the different species cannot be distinguished in historical data.

The 2013 tier 1 assessment (Day & Klaer 2013) was updated in 2016 (Day 2016) and finalised in January 2017 (Day 2017). The assessment was updated with catch, discard, CPUE, length and age data, and ageing error data for an additional three years to 2015 (Day 2016). The assessment reports spawning biomass depletion as a percentage of its unfished level. The final base-case model forecasted the 2017 spawning stock biomass to be 42 per cent of unfished spawning biomass (Day 2017; Figure 9.17). This was a reduction from the spawning stock biomass forecast in 2014, which was 50 per cent of unfished spawning biomass (Day & Klaer 2013).

The target reference point for flathead has been set at 0.4B0 (Morison et al. 2013), reflecting a more conservative biomass at maximum sustainable yield (BMSY) than the 2013 assessment's model-estimated BMSY and biomass at maximum economic yield (BMEY) of 0.32B0 and 0.38B0, respectively. Using 0.4B0 as the target reference point, the 2013 assessment (which was used to derive the TAC for the 2016–17 fishing season) estimated a three-year RBC of 3,334 t and a five-year RBC of 3,252 t. The TAC for the 2016–17 fishing season was 2,882 t.

FIGURE 9.17 Estimated spawning stock biomass for flathead, 1913 to 2015
Source: Day 2016, 2017
Stock status determination

The most recent assessment forecasts the spawning biomass of tiger flathead to be above the target reference point. As a result, the stock is classified as not overfished.

For the 2016–17 fishing season, the agreed TAC was 2,882 t, the actual TAC was 3,030.6 t and the RBC was 3,334 t. Total landed catch was 2,875 t, and the weighted average discards were 225.18 t. The landed catch and discards combined was 3,100.18 t, which is below the RBC of 3,334 t. The stock is therefore classified as not subject to overfishing.

Gemfish, eastern zone (Rexea solandri)

Gemfish, eastern zone (Rexea solandri) 

Line drawing: Sharne Weidland

Stock structure

There are two biologically distinct stocks of gemfish in Australia: an eastern stock and a western stock, separated by a boundary at the western end of Bass Strait (Colgan & Paxton 1997; Moore et al. in press).

Catch history

Catch of gemfish (eastern zone) peaked in 1978 at more than 6,000 t. Catch decreased rapidly after about 1987 (Figure 9.18). Commonwealth landed catch in the 2016–17 fishing season was 30.4 t. The weighted average discards between 2012 and 2015 were 46.84 t (Thomson & Upston 2016).

FIGURE 9.18 Gemfish annual catches (CTS, SHS and state combined) and fishing season TACs, eastern zone, 1968 to 2016
Notes: TAC Total allowable catch. Data for 2015 to 2016 do not include discards and state catch.
Source: Little & Rowling 2011; Australian Fisheries Management Authority catch disposal records (2009 to 2016 data); CSIRO Integrated Scientific Monitoring Program (2009 to 2014 discard data)
Stock assessment

The most recent full tier 1 assessment for eastern gemfish was updated in 2010 with data on catch and length frequency up to 2009 (Little & Rowling 2011). The base-case model estimated that the spawning stock biomass in 2009 was 15.6 per cent of the 1968 level (0.156SB0; Figure 9.19). A preliminary tier 1 update on the 2010 assessment indicated that the spawning stock biomass in 2015 had decreased to 8.3 per cent (0.083SB0), likely as a result of a lack of recruitment in the fishery (AFMA 2016c). Eastern gemfish is subject to a stock rebuilding strategy (AFMA 2015b) and an incidental catch allowance of 100 t.

The 2010 assessment (Little & Rowling 2011) included projections of eastern gemfish biomass that were based on two scenarios: total catches of 100 t each year and zero catches each year. The projection for zero catch indicated that biomass might reach the limit reference point of 0.2SB0 by 2017. Projections for annual catches of 100 t reached the limit in 2025 (Little & Rowling 2011).

In 2011, ShelfRAG considered an analysis of spawning potential ratio (SPR) based on the 2010 assessment (Little 2012). The SPR provides a measure of annual fishing mortality, expressed as the ratio of the spawning ability of the current stock to that of the unfished (‘equilibrium') stock. The SPR analyses (Little 2012) suggest high fishing mortality rates for eastern gemfish until the late 1990s, but much lower rates since 2002. The SPR fell to less than 30 per cent of the unfished level in the late 1980s, but has remained above 80 per cent since 2002 (Little 2012).

The revised eastern gemfish stock rebuilding strategy (AFMA 2015b) states that eastern gemfish should be rebuilt to, or above, the limit reference point by 2027 (19 years from 2008). However, this rebuilding projection is based on average levels of recruitment and assumes that total removals are limited to the 100 t incidental catch allowance.

For the 2016–17 fishing season, trawl (24 t) and non-trawl (6 t) landings (30 t in total) were comparable to the landings in the previous two seasons (37 t in 2014–15 and 30 t in 2015–16). Discards in 2014 and 2015 were 33 t and 35 t, respectively. These are lower than the 2013 discards, which were around 131 t—around double the landed catch at the time (Thomson & Upston 2016). For the 2016–17 season, total removal was 77.24 t (30.4 t was landed and weighted average discards were 46.84 t), which is below the 100 t incidental catch allowance. Stronger year-classes moving through the fishery and high discard rates may be a sign of increased recruitment and stock rebuilding; however, age-frequency data for 2014 show a strong truncation, with few mature fish (Thomson et al. 2015a). The reasons for this are unclear; contributing factors may include industry efforts to avoid the species, unfavourable environmental conditions, or distribution of the fish in the population.

Moore et al. (in press) estimated the effective population sizes for both the eastern and western stocks of gemfish using microsatellite markers. The results suggest that genetic drift is occurring in the eastern stock but not in the western stock. This suggests that the spawning biomass in the eastern stock has fewer effective genetically successful contributors between generations than expected. Hybridisation between the eastern and western populations was detected; however, there was no evidence of introgression of genetic material between the populations, suggesting that all hybrids are sterile. It is unclear at this stage what is contributing to the decreased effective population size in eastern gemfish.

FIGURE 9.19 Estimated spawning stock biomass of gemfish, eastern zone, 1965 to 2008
Source: Little & Rowling 2011
Stock status determination

The most recent (2010) estimate of spawning stock biomass was 15.6 per cent of the 1968 level in 2008, which is below the limit reference point (0.2SB0). As a result, eastern gemfish remains classified as overfished.

Total landed catch was 30.3 t, and the weighted average discards were 46.84 t. The landed catch and discards combined was 77.14 t, which is below the incidental catch allowance of 100 t for the 2016–17 fishing season. The recent catch history includes years when the incidental catch allowance was exceeded, indicating that management arrangements may not be sufficient to limit fishing mortality. The stock is therefore classified as uncertain if subject to overfishing.

Gemfish, western zone (Rexea solandri)

Stock structure

The eastern and western gemfish stocks in Australia are separated by a boundary at the western end of Bass Strait (Colgan & Paxton 1997; Moore et al. in press). Genetic studies indicate that gemfish throughout the western zone, including in the CTS and in the GABTS, is one biological stock (Moore et al. in press).

Catch history

Western gemfish is fished in both the GABTS and the CTS; however, the TAC applies only to the CTS stock. Western gemfish is targeted in the CTS, whereas incidental catches are more common in the GABTS. Western gemfish was targeted in the GABTS over four years from 2004 to 2007, and catches were as high as 532 t (Figure 9.20). In 2008, targeted fishing for western gemfish in the GABTS ceased and catches became largely incidental, partly due to low prices for gemfish and a key vessel leaving the fishery (AFMA 2010). Commonwealth landed catch in the 2016–17 fishing season was 73.3 t (Figure 9.20). The weighted average discards between 2012 and 2015 were 63.07 t (Thomson & Upston 2016).

FIGURE 9.20 Gemfish annual catches (CTS and SHS) and fishing season TACs, western zone, 1986 to 2016
Note: TAC Total allowable catch. Data for 2016 exclude discards.
Source: Haddon 2013a; Australian Fisheries Management Authority catch disposal records (2013 to 2016 catch data)
Stock assessment

Management arrangements for western gemfish currently differ between the CTS and the GABTS. Western gemfish catch in the CTS is currently restricted by a three-year multiyear TAC. The GABTS has not moved to implement quota for western gemfish, instead relying on a catch trigger, under which a full assessment must be undertaken if catch exceeds 1,000 t over three years (AFMA 2014e).

In 2016, western gemfish was assessed using both a tier 4 and a tier 1 analysis, using data from 1986 to 2015 (Haddon 2016b; Helidoniotis & Moore 2016).

The current tier 4 assessment includes updated data for total catches, total discards and the standardised CPUE from the CTS only (zones 40 and 50). There are uncertainties about the discard data—the amount of discarding varies between years, and the reporting of discards is uncertain (Helidoniotis & Moore 2016).

The 2016 tier 1 assessment was an update of the 2014 assessment. It included updated data from both the CTS and the GABTS. Data included catch-and-effort data, and age error data. The estimated spawning biomass depletion for the CTS and the GABTS combined from the tier 1 assessment was 43 per cent, which is between the limit (0.2SB0,) and target (0.48SB0) reference points (Figure 9.21).

The standardisation of the CPUE series for western gemfish accounts for vessel participation and gear variability. However, the varying discard rate changes in fishing grounds and the potential for hyperstability in this aggregating species (that is, the CPUE remains stable while stock biomass is changing) are not explicitly accounted for in the standardisation. If CPUE estimates are not indexing stock biomass, then CPUE estimates may mislead both tier 4 and tier 1 assessments (Haddon 2016b).

FIGURE 9.21 Estimated spawning stock biomass of gemfish, western zone, 1985 to 2015, for the CTS and the GABTS
Source: Helidoniotis & Moore 2016
Stock status determination

The estimated spawning biomass depletion for the CTS and the GABTS combined from the tier 1 assessment was 43 per cent, which is between the limit (0.2SB0) and target (0.48SB0) reference points. The stock is therefore classified as not overfished.

The agreed and actual TACs were 247 and 261 t, respectively. The landed catch for the 2016–17 season was 73.3 t, and the weighted average discards were 63.07 t, giving a total of 136.37 t, which is below the estimated RBC of 247 t. The stock is therefore classified as not subject to overfishing.

Gulper sharks (Centrophorus harrissoni, C. moluccensis, C. zeehaani)

Gulper sharks (Centrophorus harrissoni, C. moluccensis, C. zeehaani) 

Line drawing: FAO

Stock structure

Gulper sharks are assessed as a multispecies stock. Harrisson's dogfish (Centrophorus harrissoni) is endemic to south-eastern Australia, from southern Queensland to south-eastern Tasmania, and adjacent seamounts. Southern dogfish (C.zeehaani) is endemic to southern Australia, from Shark Bay in Western Australia to Forster in New South Wales (Williams et al. 2013). Endeavour dogfish (C.moluccensis) has a broader range than Harrisson's and southern dogfish, extending beyond the boundaries of the SESSF and Australia. Within Australia, endeavour dogfish occurs along the west and east coasts, but is uncommon off the south coast (Last & Stevens 2009). Greeneye spurdog (Squalus chloroculus) is widely distributed in temperate and subtropical waters of most oceans, and may constitute a species complex (Last & Stevens 2009).

To support the revision of the AFMA Upper-slope dogfish management strategy (AFMA 2012) in 2013, Williams et al. (2013) investigated the relative carrying capacity and depletion of subpopulations of Harrisson's and southern dogfish. Results indicated different depletion levels in different areas, suggesting the separation of gulper sharks into several populations: a continental margin and a seamount population for Harrisson's dogfish; and eastern, central and western populations for southern dogfish.

Catch history

Estimated landings of gulper sharks (derived from liver oil production from 1994 to 2001) averaged about 20 t (trunk weight) from 1994 to 1998, with a peak of 40 t in 1995. Catches averaged about 10 t from 2002 to 2005 and have since declined. Despite gulper sharks being a no-take multispecies stock, landings for the trawl fishery were 0.3 t in the 2016–17 season (Figure 9.22). This may reflect reporting errors.

FIGURE 9.22 Gulper shark annual catch and discards for the SESSF (all sectors), 1994 to 2016
Notes: Estimated catch of upper-slope gulper sharks from 1994 to 2001 is based on liver oil quantity. Catch history is compiled using data from various sources.
Stock assessment

Gulper sharks, similar to many other deepwater sharks, have very low productivity due to a slow growth rate, late age at maturity and low fecundity. These life-history characteristics place them at higher risk of rapid depletion at low levels of fishing effort, and make their recovery slow once stocks are depleted (Daley et al. 2002; Simpfendorfer & Kyne 2009; Williams et al. 2013). Williams et al. (2013) have shown that gulper sharks undertake day–night migrations across their depth range, from relatively deep daytime residence depths (to 1,000 m) to shallower night-time feeding depths (up to 200 m), rendering them susceptible to capture over a wide depth range. Williams et al. (2013) also found that the geographic distribution of fishing during periods of high fishing effort in the CTS (1984 to 2011), demersal and auto-longline fisheries (1992 to 2010), Commonwealth gillnet fisheries (1997 to 2010) and New South Wales state fisheries coincides with the most depleted areas of Harrisson's and southern dogfish. Post-capture survival of gulper sharks in the trawl sector is low; most gulper sharks are dead when the net is hauled. In the auto-longline sector, post-capture survival is potentially higher (subject to fishing gear soak time and handling practices); a preliminary study by CSIRO estimated post-capture survival at 60–93 per cent for the 70 southern dogfish tagged and released in the study (Williams et al. 2013).

Gulper sharks were historically targeted because they have high squalene (liver oil) content. The resulting historical depletion of gulper sharks off the east coast is well documented (Graham et al. 2001; Wilson et al. 2009). Graham et al. (2001) reported declines in catch rate of 95.8–99.9 per cent between research trawl surveys conducted in 1976–77 and 1996–97 for greeneye spurdog, and endeavour, Harrisson's and southern dogfish on the New South Wales upper slope. Williams et al. (2013) derived depletion estimates for the identified subpopulations of Harrisson's and southern dogfish, expressed as a percentage of the initial relative carrying capacity. For Harrisson's dogfish, the continental margin population was estimated to be at 11 per cent of carrying capacity (range 4–20 per cent) and the seamount population at 75 per cent (range 50–100 per cent). For southern dogfish, the eastern population was estimated to be at 11 per cent of carrying capacity (range 6–19 per cent) and the central population at 16 per cent (range 8–33 per cent). No estimate could be derived for the western population of southern dogfish because of limited data availability. Williams et al. (2013) confirmed that, in some areas, large reductions in abundance had resulted from quite low levels of fishing effort.

AFMA released the Draft upper slope dogfish management strategy in 2009, which protected several areas of known occurrence of dogfish, and implemented daily catch and trip limits (AFMA 2009b). The strategy was reviewed by Musick (2011) and found to be inadequate to ensure recovery of Harrisson's, southern and endeavour dogfish, and greeneye spurdog, with fishing mortality still exceeding estimated sustainable levels. The strategy was subsequently revised in 2012, following research on depletion rates of upper-slope dogfish subpopulations (Williams et al. 2013), with a recovery objective of rebuilding Harrisson's and southern dogfish stocks to 25 per cent of their original carrying capacity. Williams et al. (2013) examined the amount of core habitat area for Harrisson's and southern dogfish that would be protected under a proposed closure network designed to meet this objective. Under the closure network, it is estimated that, in AFMA-managed waters, 25 per cent of the core habitat of Harrisson's dogfish on the continental shelf and slope, 16.2 per cent of the core habitat of the eastern population of southern dogfish and 24.3 per cent of the core habitat of the central population of southern dogfish would be protected (from trawling and/or demersal longline fishing). These closures were implemented in February 2013. Additional closures were subsequently implemented on the Tasmanian seamounts (Queensland, Britannia and Derwent Hunter) overlaying the Murray and Freycinet Commonwealth marine reserves (areas that allow access to line fishing) (AFMA 2014e).

On 30 May 2013, the Minister for Sustainability, Environment, Water, Population and Communities listed Harrisson's dogfish and southern dogfish under the EPBC Act as threatened species in the conservation dependent category. The minister noted that both species have experienced severe historical declines following overfishing, and are subject to recovery plans that provide for management actions to stop their decline and support their recovery. Measures to further reduce fishing mortality include a combined trigger limit of three Harrisson's dogfish and/or southern dogfish; a zero retention limit for greeneye spurdog, and Harrisson's, southern and endeavour dogfish; and guidelines for handling practices. In 2014, a research and monitoring workplan was developed to establish methods for monitoring the rebuilding of dogfish abundance.

Stock status determination

In the absence of any evidence of recovery to above the limit reference level, gulper sharks remain classified as overfished because of the substantial depletion of Harrisson's and southern dogfish in areas of southern and eastern Australia.

The level of reported catch (including discards) has declined over the past decade, and was very low in the 2015–16 and 2016–17 fishing seasons (<1 t and 0.3 t, respectively). However, there is potential for unreported or underestimated discards, based on the large degree of overlap of current fishing effort with the core range of the species. Low levels of mortality can pose a risk for such depleted populations. Although it has been estimated that the closures implemented in 2013 will protect 16.2–25 per cent of the core distribution areas of these species, no evidence has yet been obtained showing rebuilding, and the effect of the closures remains to be seen. As a result, gulper sharks are classified as uncertain with respect to the level of fishing mortality. Resolution of stock structure may result in one or more of the subpopulations being classified as not subject to overfishing.

Jackass morwong (Nemadactylus macropterus)

Jackass morwong (Nemadactylus macropterus) 

Line drawing: FAO

Stock structure

Jackass morwong is distributed around the southern half of Australia (including Tasmania), New Zealand, and St Paul and Amsterdam islands (Indian Ocean); and off south-eastern South America and southern Africa. It occurs to depths of 450 m and, in Australian waters, is most abundant between 100 and 200 m. Genetic studies have shown no evidence of separate stocks in Australian waters, but found that New Zealand and Australian stocks are distinct (Elliott & Ward 1994). Although analysis of otolith microstructure found differences between jackass morwong from southern Tasmania and those off New South Wales and Victoria, it is unclear whether such differences indicate separate stocks (Morison et al. 2013). Nonetheless, it is assumed for the purposes of the stock assessment that there are separate stocks of jackass morwong in the eastern and western zones (Morison et al. 2013), and therefore separate quantitative (tier 1) stock assessment models are undertaken for the eastern (southern New South Wales to eastern Tasmania) and western (western Tasmania to western Victoria) stocks. Catches of jackass morwong are also reported from the GABTS (Chapter 11), but this stock is currently managed separately from the western stock.

Catch history

Catches of jackass morwong peaked at more than 2,500 t in the mid 1960s and have declined since the 1980s. They have continued to decline over the past five years and have been less than 500 t per year (Figure 9.23). Commonwealth landed catch in the 2016–17 fishing season was 213 t. The weighted average discards between 2012 and 2015 were 30.25 t (Thomson & Upston 2016).

FIGURE 9.23 Jackass morwong annual catches (CTS, SHS and state combined) and fishing season TACs, east – and west – stocks combined, 1915 to 2016

Notes: TAC Total allowable catch. Data for 2015 to 2016 do not include discards and state catches.
Source: Tuck et al. 2015; Australian Fisheries Management Authority catch disposal records (2016 catch data)

Stock assessment

The eastern and western stocks were assessed in 2011 (Wayte 2012), 2013 (Wayte 2014) and 2015 (Tuck et al. 2015). Assessments of western jackass morwong are uncertain because only sporadic age data are available, length compositions are based on a very low number of sampled fish, and catches in the west are low (only 23 t was reported in logbooks in 2015–16) (AFMA 2015a). While noting these concerns, ShelfRAG accepted the 2015 assessment (AFMA 2015c) because the outcome of the 2015 assessment was reasonably consistent with the 2011 assessment. The 2015 assessment predicted the spawning stock biomass to be 0.69B0 in 2016 (compared with 0.68B0 in 2012), which is above the target reference point of 0.48B0 (Figure 9.24).

Previous stock assessments for eastern jackass morwong indicated a gradual recovery from below the limit reference point (0.2SB0) in the early 2000s. The new stock assessment (Tuck et al. 2015) predicted spawning biomass to be 0.365B0 in 2016 (compared with 0.4B0 in 2012), which is between the limit reference point (0.2B0) and the target reference point (0.48B0).

ShelfRAG (AFMA 2011) noted that model estimates of recruitment for the eastern stock since the late 1980s have been consistently below the average predicted by the stock–recruitment relationship. In 2011, ShelfRAG accepted a new base-case assessment for the eastern stock that involved a change in productivity (a ‘regime shift'), attributed to long-term oceanographic changes (Wayte 2013). The assessment for the eastern stock uses separate stock–recruitment relationships before and after 1988, with lower recruitment after 1988. Compared with older assessments, the 2012 and 2015 assessments provided a better fit to the data, although they remained sensitive to the value of natural mortality and the choice of the last year for which recruitment was estimated. Management strategy evaluation predicted a lower risk of the biomass falling below the limit reference point if total removals were consistent with the RBCs derived from the assessments that assumed this recruitment shift (Morison et al. 2013). The 2015 assessment was used to calculate the RBCs for the 2016–17 season of 249 t for the west and 314 t for the east (combined RBC is 563 t).

FIGURE 9.24 Estimated spawning stock biomass for eastern (1988 to 2014) and western (1984 to 2014) stocks of jackass morwong
Note: Biomass estimates are available for the eastern stock from 1915 to 1987. However, pre-1988 estimates are not presented for the eastern stock because the new ‘regime shift' base case resets the reference biomass to the unfished equilibrium biomass in 1988.
Source: Tuck et al. 2015
Stock status determination

The most recent assessment (Tuck et al. 2015) estimates that spawning biomass depletion of western jackass morwong in 2016 is 66 per cent (0.66SB0), which is above the target reference point of 0.48SB0. Based on logbook data, catch of the western stock (62.7 t in 2016–17) is below the RBC of 249 t estimated by the 2015 assessment, indicating that the western stock is not overfished and not subject to overfishing.

For eastern jackass morwong, acceptance of a recruitment shift in the assessment resulted in decreased estimates of recent depletion, from close to the limit reference point (0.2B0) in 2011 to 0.37B0 (37 per cent of the 1988 equilibrium biomass) in 2016. Eastern catches have declined in response to reduced TACs. Based on logbook data, catches of the eastern stock (131 t in 2016–17) are below the RBC of 314 t estimated in the 2015 assessment, and the stock is therefore classified as not overfished and not subject to overfishing.

For the 2016–17 fishing season, the agreed TAC was 474 t, the actual TAC was 533 t and the RBC was 563 t. Total landed catch was 213 t, and the weighted average discards were 30.25 t. The landed catch and discards combined was 243.2 t, which is below the RBC of 563 t. Based on this information, jackass morwong is classified as not overfished and not subject to overfishing.

John dory (Zeus faber)

John dory (Zeus faber) 

Line drawing: Rosalind Poole

Stock structure

John dory inhabits coastal and continental-shelf waters of Australia, the western Indian Ocean, the eastern Atlantic Ocean, the Mediterranean Sea, Japan and New Zealand. In southern Australia, its distribution stretches from Moreton Bay in southern Queensland to Cape Cuvier in Western Australia, with a limited distribution in eastern Bass Strait. In recent years, most of the SESSF john dory catch has been taken off New South Wales and eastern Victoria (Morison et al. 2013). John dory in the SESSF is considered to constitute a single stock for assessment and management purposes.

Catch history

The catch of john dory averaged between 200 and 300 t from 1986 to 1995, peaking at about 400 t in 1993. Catches then decreased and have been below 200 t per year since 2000. Catches have been below 100 t per year for half of the eight fishing seasons since 2006 (Figure 9.25). Commonwealth landed catch in the 2016–17 fishing season was 81.8 t. The weighted average discards between 2012 and 15 were 1.92 t (Thomson & Upston 2016).

FIGURE 9.25 John dory annual catches (CTS, SHS and state combined) and fishing season TACs, 1986 to 2016
Notes: TAC Total allowable catch. Data for 2014 to 2016 do not include discards and state catch.
Source: Haddon 2013a; Australian Fisheries Management Authority catch disposal records (2014 to 2016 catch data)
Stock assessment

John dory is infrequently targeted in the SESSF. Most of the catch was historically taken as byproduct by trawlers targeting other shelf species, such as redfish and flathead. Because most john dory catches are not targeted, it is considered a ‘secondary species' rather than a target species, and is managed to the default BMSY proxy target of 0.4B0.

The 2014 tier 3 assessment for john dory (Thomson 2014) updated yield analyses presented in Klaer (2013) using a yield-per-recruit model. Recent average total mortality was estimated from catch curves constructed from length-frequency information. The assessment estimated an equilibrium fishing mortality rate (FCURR) of 0.120, which was below the target fishing mortality reference point (Fspr40 = 0.159) that would achieve a biomass of 0.4B0. This indicated that the current biomass was above this target. Using the 0.4B0 target, the assessment produced an RBC of 203 t for the 2016–17 fishing season. ShelfRAG recommended a three-year multiyear TAC of 169 t (AFMA 2014f). The 2016–17 TAC was set at 167 t.

In 2014, ShelfRAG considered suitable breakout rules for the john dory multiyear TAC. It noted that a change in catch rate would not be appropriate because catch rate is not reflected in the tier 3 assessment. ShelfRAG therefore recommended adopting a breakout rule that it would review the available data if more than 80 per cent of the TAC is caught.

Stock status determination

Recent catches are low relative to historical levels, and the tier 3 assessment estimates that fishing mortality is below the level that would achieve the biomass target level.

For the 2016–17 fishing season, the agreed TAC was 167 t, the actual TAC was 181.5 t and the RBC was 203 t. Total landed catch was 82 t, and the weighted average discards were 1.92 t, giving a total of 83.92 t, which is below the RBC of 203 t. As a result, john dory is classified as not overfished and not subject to overfishing.

Mirror dory (Zenopsis nebulosa)

Mirror dory (Zenopsis nebulosa) 

Line drawing: FAO

Stock structure

Mirror dory is found throughout the southern Pacific Ocean at depths of 30–800 m. A single stock of mirror dory in the SESSF area is assumed for management purposes (Morison et al. 2013).

Catch history

Catch of mirror dory has generally been stable over time, ranging between 200 and 700 t per year (Figure 9.26). In the 2016–17 fishing season, the RBC for the eastern stock was 362 t and the RBC for the western stock was 129 t. The total RBC was 491 t. Commonwealth landed catch in the 2016–17 fishing season was 275 t. The weighted average discards between 2012 and 2015 were 14.18 t (Thomson & Upston 2016).

FIGURE 9.26 Mirror dory annual catches (CTS, SHS and state combined) and fishing season TACs, 1986 to 2016
Notes: TAC Total allowable catch. Data for 2015 and 2016 do not include discards and state catch.
Source: Haddon 2015; Australian Fisheries Management Authority catch disposal records (2016 catch data).
Stock assessment

Most of the mirror dory catch is byproduct in the CTS and is mainly caught east of Bass Strait. A quantitative (tier 1) assessment was attempted in 2010, but ShelfRAG considered that it was not sufficiently robust because there was uncertainty around the natural mortality rate, and a time series of age-composition data was not available (AFMA 2013b).

Previous tier 3 catch-curve assessments of mirror dory have used a growth equation applied to length data to estimate age composition. The 2013 tier 3 assessment estimated current fishing mortality (FCURR) at 0.285, which was above the target fishing mortality reference point (F = 0.147; Klaer 2013). However, in 2013, ShelfRAG rejected the tier 3 assessment, noting that the mortality estimation model was not fitting the descending limb of the age distribution, and had previously underestimated F and overestimated RBCs (AFMA 2013b). Tier 3 assessments were used to determine RBCs for the 2012–13 and 2013–14 fishing seasons; this explains the large increase in TAC in Figure 9.27.

Because of the ongoing uncertainty in the tier 3 assessments, ShelfRAG decided to base advice for 2013–14, 2014–15 and 2015–16 on tier 4 assessments using standardised CPUE, which were conducted separately for mirror dory east (zones 10 to 30) and west (zones 40 and 50) of Bass Strait because spatial catch data were available. The CPUE in the west has fluctuated since 1990, with recent average CPUE between the limit and the target level (Figure 9.27; Haddon 2016b). In the east, CPUE decreased towards the limit from 1993 to around 2000, and then increased back to above the target by 2005 (Figure 9.28); the CPUE trend over the last four years indicates a steady decrease in CPUE, with the recent average CPUE between the limit and the target (Table 6 in Haddon 2016b).

FIGURE 9.27 Standardised CPUE for western mirror dory, 1986 to 2015
Note: CPUE Catch-per-unit-effort.
Source: Haddon 2016b
FIGURE 9.28 Standardised CPUE for eastern mirror dory, 1986 to 2015
Note: CPUE Catch-per-unit-effort.
Source: Haddon 2016b
Stock status determination

Recent tier 4 assessments indicate that the recent average CPUE for the eastern and western stocks is above the limit reference point, and the stock is classified as not overfished.

For the 2016–17 fishing season, the agreed TAC was 325 t, the actual TAC was 362 t and the RBC was 491 t. Total landed catch was 275.1 t, and the weighted average discards were 14.18 t. The landed catch and discards combined was 289.28 t, which is below the RBC of 491 t. The stock is therefore classified as not subject to overfishing.

Mirror dory
AFMA

Ocean jacket (predominantly Nelusetta ayraud)

Ocean jacket (predominantly Nelusetta ayraud) 

Line drawing: FAO

Stock structure

The ocean jacket stock comprises chinaman leatherjacket, which makes up most of the catch, and unspecified leatherjackets. Little is known about the biological structure of this multispecies stock. Ocean jacket taken in the GABTS is assessed separately (Chapter 11).

Catch history

Total catch of ocean jacket remained stable, at around 50 t, between 1986 and 2001 (Figure 9.29). Since then, ocean jacket has been an important non-quota byproduct species in the SESSF, with current catch levels exceeding those of many quota species. Catch peaked in 2016 at 475 t. Commonwealth landed catch in the 2016–17 fishing season was 288.7 t.

FIGURE 9.29 Ocean jacket catch in the CTS and SHS, 1986 to 2016
Note: Catch includes chinaman leatherjacket and unspecified leatherjackets.
Source: Sporcic 2015; Australian Fisheries Management Authority catch disposal records (2016 catch data)
Stock assessment

Historical catch data indicate substantial variations in ocean jacket abundance off south-eastern Australia in the 1920s and 1950s (Miller & Stewart 2009). Ocean jacket is a relatively short-lived species (six years), reaching maturity within two to three years and exhibiting large cyclical changes in abundance (Miller & Stewart 2009). As a byproduct species, ocean jacket has not been the subject of formal stock assessments. A standardised CPUE series has been constructed in recent years, which shows a similar trend to landings, suggesting that abundance of ocean jacket increased after 2003 (Figure 9.30; Sporcic & Haddon 2016). Catch rates for ocean jacket from zones 10 to 50 have decreased only slightly (Sporcic & Haddon 2016). There continues to be uncertainty over discarding of this species in the CTS and the GHTS; thus, the effect of discarding on CPUE trends is unknown (Upston & Thomson 2015).

FIGURE 9.30 Standardised CPUE for ocean jacket, 1986 to 2014
Note: CPUE Catch-per-unit-effort. There is no tier 4 assessment for ocean jacket, and so there are no target and limit reference points.
Source: Sporcic & Haddon 2016
Stock status determination

There is no formal stock assessment for ocean jacket. The standardised CPUE index increased substantially between 2003 and 2007, and remains high. Ocean jacket is therefore classified as not overfished. Despite recent high catches, catch rates have remained high compared with historical levels, and therefore ocean jacket is classified as not subject to overfishing.

Ocean perch (Helicolenus barathri, H. percoides)

Ocean perch (Helicolenus barathri, H. percoides) 

Line drawing: FAO

Stock structure

Ocean perch is managed as a single stock that includes two species: the inshore reef ocean perch (Helicolenus percoides) and the offshore bigeye ocean perch (H.barathri). Ocean perch stock structure is uncertain, but there is probably an east–west structuring of stocks (Morison et al. 2013). The reef (inshore) ocean perch and the bigeye (offshore) ocean perch have been assessed separately since 2009, but a single all-areas TAC is set for the two species. Based on the depth of capture and logbook records, most of the landed ocean perch is considered to be bigeye (offshore) ocean perch.

Catch history

Bigeye (offshore) ocean perch has been a significant part of trawl catches since the continental-slope trawl fishery developed in the late 1960s (Morison et al. 2013). Landed catch of ocean perch since the 1970s has generally been between 200 and 400 t, increasing from 200 t in the 1980s to around 400 t from 1995 to 2004, before decreasing again to around 200 t from 2007 to 2014 (Figure 9.31). Commonwealth landed catch in the 2016–17 fishing season was 162.9 t. The weighted average discards between 2012 and 2015 were 148.72 t (Thomson & Upston 2016). Most reef (inshore) ocean perch (around 95 per cent in recent years) are discarded because of their smaller size (Upston & Thomson 2015). Discard rates for bigeye ocean perch are much lower; around 11 per cent of total catch was estimated to have been discarded in 2014 (Upston & Thomson 2015).

FIGURE 9.31 Total ocean perch (reef [inshore] and bigeye [offshore]) annual catches (CTS, SHS and state combined) and fishing season TACs, 1986 to 2016
Notes: TAC Total allowable catch. Data for 2013 to 2016 exclude discards and state catch.
Source: Haddon 2013a; Australian Fisheries Management Authority catch disposal records (2013 to 2016 catch data)
Stock assessment

ShelfRAG provides advice based on B40 (BMSY proxy) target reference points for both bigeye (offshore) and reef (inshore) ocean perch stocks (Morison et al. 2013).

Tier 4 standardised CPUE assessments were last updated in 2013 (Haddon 2013a). ShelfRAG noted the high but uncertain estimates of discard rates for reef ocean perch and recommended the application of a 15 per cent discount factor to the RBC for added precaution (Morison et al. 2013). Using the B40 target, ShelfRAG recommended a three-year RBC of 102 t for reef ocean perch and 283 t for bigeye ocean perch (385 t total). The multiyear TAC set by the AFMA Commission for the 2014–15 to 2016–17 fishing seasons was 195 t, covering both species; however, after the 15 per cent deduction to account for the uncertainty in tier 4 assessment methods, and deductions for state catches and discards, the multiyear TAC was reduced to 190 t. The Commonwealth landed catch in the 2016–17 fishing season was 163 t. Annual landings by New South Wales state fishers have been around 15–36 t since 2000 (Thomson & Upston 2016).

The weighted average discards between 2012 and 2015 were 148.72 t (Thomson & Upston 2016). Although discards of this species are high and variable, and have substantial influence on CPUE values, recent discards are well estimated by the Integrated Scientific Monitoring Program, and ShelfRAG concluded that the inclusion of discards provided a more reliable index of abundance (AFMA 2013c).

The 2013 assessment for reef ocean perch indicated that CPUE (including discards) had dropped below the limit reference point during the period 2005 to 2008, but then increased to above the target after 2010. The recent average CPUE was above the target reference point (Figure 9.32); estimates of recent discards contributed substantially to the high estimates of CPUE in recent years.

FIGURE 9.32 Standardised CPUE, including discards, for reef (inshore) ocean perch, 1986 to 2012
Notes: CPUE Catch-per-unit-effort. Standardised CPUE after 2012 is not shown because there has been no new tier 4 assessment.
Source: Haddon 2013a

The CPUE to 2012 for bigeye ocean perch (Haddon 2013a) indicates stability in catch rates since 1996, but a decline for two consecutive years since 2013 (Sporcic & Haddon 2016). Standardised CPUE remained above the limit reference point (Figure 9.33; Sporcic & Haddon 2016).

FIGURE 9.33 Standardised CPUE for bigeye (offshore) ocean perch, 1986 to 2012
Notes: CPUE Catch-per-unit-effort. Standardised CPUE after 2012 is not shown because there has been no new tier 4 assessment.
Source: Haddon 2013a
Stock status determination

The 2013 tier 4 assessment, including discards, found reef (inshore) ocean perch to have rebuilt to the target by 2010. Since 2013, CPUE trends have declined but likely remain above the limit reference point (Sporcic & Haddon 2016). In the absence of an updated stock assessment, reef (inshore) ocean perch remains classified as not overfished. Landed catches from logbook data totalled 3 t, and the average weighted discards were 114.77 t (Thomson & Upston 2016). The landed catch and discards combined was 117.77 t, which is higher than the three-year RBC of 102 t (AFMA 2013d). Based on this information and the declining CPUE trends, reef (inshore) ocean perch is determined to be uncertain if subject to overfishing.

The 2013 tier 4 assessment for bigeye (offshore) ocean perch indicates that the stock biomass is above the limit reference point; therefore, the stock is assessed as not overfished. Landed catches from logbook data totalled 92.4 t, and the average weighted discards were 33.95 t (Thomson & Upston 2016). The landed catch and discards combined was 126.4 t, which is lower than the three-year RBC of 283 t (AFMA 2013d). Ocean perch is therefore determined to be not subject to overfishing.

For the 2016–17 fishing season, the agreed TAC was 190 t, the actual TAC was 194.3 t and the RBC was 283 t. Total landings from catch disposal records were 163 t, and the weighted average discards were 148 t, giving a total of 311 t, which is above the RBC of 283 t (AFMA 2016b). Total catches in 2013–14 and 2014–15 also exceeded the RBC by 185 and 176 t, respectively. It is unclear if this level of fishing mortality will move the stock to an overfished state. Based on this information, the combined stock of reef and bigeye ocean perch is classified as not overfished but uncertain if subject to overfishing.

Orange roughy (Hoplostethus atlanticus)

Orange roughy (Hoplostethus atlanticus) 

Line drawing: Rosalind Poole

Stock structure

A study on genetic variation in orange roughy (Gonçalves da Silva et al. 2012) examined the variation of a large number of loci using genetic techniques that have the power to detect low levels of genetic differentiation. The study concluded that orange roughy within the Australian Fishing Zone form a single genetic stock, but identified some differentiation between Albany/Esperance, Hamburger Hill (in the Great Australian Bight) and south-eastern Australia. It was noted that the amount of genetic exchange needed to maintain genetic homogeneity is much less than the amount needed for demographic homogeneity, and that residency or slow migration may result in separate demographic units despite genetic similarity (Morison et al. 2013). Orange roughy on the Cascade Plateau has distinct morphometrics, parasite populations, size and age composition, and spawning time, and is considered to be a separate management unit within the Southern Remote Zone (AFMA 2014g). The fishery is managed and assessed as a number of discrete regional management units (Figure 9.34).

FIGURE 9.34 Management zones for orange roughy in the SESSF

Overall catch history

Orange roughy was historically targeted in aggregations around seamounts, mainly at depths from 600 m to about 1,300 m. The first aggregation was discovered off Sandy Cape, western Tasmania, in 1986 (Smith & Wayte 2004). Several other non-spawning aggregations were discovered in 1986 and 1988, producing annual landings ranging from 4,600 to 6,000 t. The discovery of a large spawning aggregation on St Helens Hill and elsewhere off eastern Tasmania in 1989 resulted in significant growth of the fishery, with declared catches exceeding 26,000 t in 1989 and 40,000 t in 1990, making this the largest and most valuable finfish fishery in Australia at the time (Morison et al. 2013). Catches declined steadily after 1990, reaching low levels between 2000 and 2005. Following indications of decreasing catch rates and availability, the introduction of management zones and TACs prevented further increases in catches of orange roughy (Smith & Wayte 2004). Individual catch histories for the Cascade Plateau, eastern, southern and western orange roughy zones are shown in Figures 9.35, 9.36, 9.38 and 9.39.

In October 2006, orange roughy was listed as conservation dependent under the EPBC Act and placed under the Orange Roughy Conservation Programme (ORCP). The ORCP was replaced by the Orange Roughy Rebuilding Strategy in 2015 (AFMA 2015d), the primary objective of which is to return all orange roughy stocks to levels at which the species can be harvested in an ecologically sustainable manner that is consistent with the HSP. Management actions to minimise fishing mortality and support rebuilding include deepwater closures, targeted fishing for orange roughy stocks that are above the limit reference point of 20 per cent of the unfished spawning biomass, restricting effort by limiting entry to existing fisheries, and ongoing research and monitoring to support stock assessments.

Danish-seine nets
Ryan Keightley, AFMA

Orange roughy, Cascade Plateau

Catch history

Orange roughy on the Cascade Plateau is the only orange roughy fishery assessed in the CTS that is not estimated to have been depleted to below the limit reference point; this fishery shows a somewhat different catch trend from the depleted fisheries. Catch of orange roughy on the Cascade Plateau peaked at 1,858 t in 1990. No catch was taken between 1991 and 1995. Catches have been below 10 t in recent years, despite the TAC remaining at 500 t, reflecting negligible effort in the fishery. Reported landed catch from the Cascade Plateau in the 2016–17 season was 0 t (Figure 9.35); discard estimates were not determined (Thomson & Upston 2016).

FIGURE 9.35 Orange roughy catch (CTS), Cascade Plateau, 1989 to 2016
Note: TAC Total allowable catch.
Source: Various, including Australian Fisheries Management Authority catch disposal records
Stock assessment

A requirement of the ORCP was to maintain the spawning biomass of orange roughy on the Cascade Plateau at or above 0.6B0. This was revised in 2015 to adopt the standard target reference point of 0.48B0 and the limit reference point of 0.2B0, in line with the default settings of the SESSF HSF (AFMA 2014h). This revised target for the Cascade Plateau stock is reflected in the Orange Roughy Rebuilding Strategy (AFMA 2015d).

Spawning aggregations of Cascade Plateau orange roughy have been assessed using acoustic survey abundance indices since 2003. These assessments rely on the single largest acoustic estimate of biomass each year, rather than trends in time series, because spawning aggregations on the Cascade Plateau are highly variable and have shown no discernible trends in volume or estimated biomass over time (Morison et al. 2013). Because fishing effort has been low, and therefore new data are lacking, the stock has not been formally assessed since 2009.

The 2006 assessment estimated female spawning biomass to be 72–73 per cent of the unfished biomass (Wayte & Bax 2007). Because the stock was assessed to be above the 0.6B0 reference point that was in place at the time, application of the SESSF HSF harvest control rules allowed the setting of TACs to enable fish-down towards the reference point. Spawning aggregations did not form in 2007 and 2008, and the TAC was undercaught for the first time in the fishery's history in 2007 (151 t caught out of a TAC of 500 t) and 2008 (121 t caught out of a TAC of 700 t). The 2009 season was initially characterised by ‘typical' orange roughy behaviour, with a large spawning aggregation forming on the western side of the plateau (Prince & Hordyk 2009). This subsequently disappeared after easterly winds and a strong easterly current developed, resulting in incursion of warmer water.

Projections from the most recent formal stock assessment for orange roughy on the Cascade Plateau, in 2009, predicted that, if the 315 t long-term RBC was fully caught by 2011, the spawning biomass of the stock would be at 0.64SB0 in 2011 (Morison et al. 2012). Taking into account the lower catch levels of 2007 and 2008, the assessment suggested that a TAC of 500 t would maintain the stock at 0.63SB0 in 2011. Noting low fishing effort and a lack of new data, AFMA has continued to set an annual TAC of 500 t. This stock was scheduled for an assessment in 2014, but the assessment was postponed because there were no new catch or acoustic data. The landed catch was 0 t in 2013–14, 0.3 t in 2014–15, 2 t in 2015–16 and 0 t in 2016–17 (Figure 9.35).

Stock status determination

The most recent assessment (2009) predicted that the 2011 spawning stock biomass of Cascade Plateau orange roughy would be at 63–64 per cent of unfished levels (0.63–0.64SB0). Because catches in 2015–16 and 2016–17 were 2 t and 0 t, respectively, and the stock biomass was assessed to be above the target, the stock remains classified as not overfished and not subject to overfishing.

Orange roughy, eastern zone

Catch history

The eastern, southern and western orange roughy fisheries show similar catch trends. The eastern zone has supported higher cumulative catches of orange roughy than the southern and western zones, producing a reported catch of 76,714 t from 1989 to 1992 (Figure 9.36).

Along with the southern and western zones, the eastern zone was declared overfished and placed under the ORCP in 2006. Orange roughy catch in the eastern zone was limited to incidental catch allowances, to allow for unavoidable catches made while targeting other species. Most of the historical fishing grounds for orange roughy deeper than 700 m were also closed to trawling in January 2007 (AFMA 2006). Targeted fishing for orange roughy in the eastern zone recommenced in the 2015–16 fishing season, following acoustic surveys and an updated stock assessment. In the 2015–16 fishing season, 436 t was landed from the eastern zone, compared with 6 t landed in 2014–15 (Figure 9.36). The Commonwealth landed catch in the 2016–17 fishing season was 363 t. The weighted average discards between 2012 and 2015 were 3.6 t (Thomson & Upston 2016).

FIGURE 9.36 Orange roughy catch (CTS), eastern zone, 1985 to 2016
Source: Upston et al. 2014; Australian Fisheries Management Authority catch disposal records (2014 to 2016 catch data)
Stock assessment

The 2006 assessment for the eastern zone (Wayte 2006) estimated that spawning stock biomass had declined to 10 per cent of unfished levels (0.1SB0), following the large catches taken in the late 1980s and early 1990s (Figure 9.37). The base-case estimate of spawning biomass from this assessment was less than 15,000 t. The 2006 model estimates of biomass were primarily driven by the substantial decline in abundance of larger and older orange roughy in the fishery.

Compensatory increases in the biological productivity of this stock appear to have occurred as a density-dependent response to the substantial decline in orange roughy abundance during the 1990s. Age at 50 per cent maturity has decreased by up to 2 years, from 30 to 28 years for males, and length-standardised fecundity is estimated to have increased by 73 per cent between 1987 and 2010 (Pitman et al. 2013).

The proportion of the population that spawns each year is uncertain and variable. It was estimated to have increased from 54 per cent in the late 1980s to 71 per cent in the early 1990s (Morison et al. 2013), with the most recent estimates being 70 per cent in 2009 and 52 per cent in 2010 (Kloser et al. 2011). As a result, the reproductive potential (a function of spawning biomass, sex ratio, maturity at age and other factors) of the stock in 2010 was estimated to be 32 per cent of that at unfished levels, despite the greatly reduced biomass (Kloser et al. 2011).

The biomass of spawning aggregations of eastern orange roughy in 2010 was estimated to be 25,400 t (95 per cent confidence interval [CI] 18,000 to 32,800 t), based on the combined results of two acoustic surveys at St Helens Hill and St Patricks Head. Assuming that the 2010 proportion of the population spawning (52 per cent) is representative of the entire mature stock, the total biomass in 2010, using the 25,400 t acoustic estimate corrected for spawning fraction, was estimated by Kloser et al. (2011) to be 48,800 t (95 per cent CI 21,100 to 76,600 t). The difference between the 2006 estimates of biomass (below 0.2B0) and the 2010 direct acoustic estimates of BCURR indicated stock rebuilding.

An assessment update was attempted in 2011 using updated commercial catch data for the eastern and southern (Pedra Branca only) zones from 1985 to 2010, the acoustic biomass indices, an egg-production estimate of spawning biomass from 1992 and age-composition data from spawning aggregations since 1992. However, SlopeRAG could not determine how to reconcile the conflict between the catch-at-age declines and increasing acoustic indices, and could not agree on a base case for the assessment. SlopeRAG did agree that the results of acoustic surveys provided evidence of stock rebuilding (AFMA 2013e).

Using new catch, acoustic and age-composition data, the 2011 assessment was updated in 2014. It predicted the 2015 female spawning biomass (SB2015/SB0) to be at 26 per cent, with a predicted unfished female spawning biomass of 38,727 t (Upston et al. 2014; Figure 9.37). This assessment was accepted by SlopeRAG.

FIGURE 9.37 Estimated female spawning stock biomass for orange roughy, eastern zone, 1980 to 2013
Source: Upston et al. 2014

The stock structure assumption used in the eastern stock assessment model is based on a single stock covering the entire eastern zone, plus orange roughy from the Pedra Branca seamount in the southern zone, because a proportion of southern zone orange roughy are hypothesised to migrate to the main spawning grounds in the eastern zone (St Helens Hill or St Patricks Head) to spawn in winter (Upston et al. 2014).

As part of the assessment, an analysis (Markov chain Monte Carlo simulation) was undertaken to explore the probabilities around different model outcomes. This analysis produced biomass and RBC estimates similar to the maximum posterior density estimates from the model. SlopeRAG subsequently recommended RBCs of 381 t for 2015–16, 512 t for 2016–17 and 647 t for 2017–18. Given the long-lived nature of orange roughy, an expectation that there would be no large year-to-year changes in age structure, and the fact that CPUE is not an adequate indicator of changes in stock status for aggregating stocks, SlopeRAG did not recommend breakout rules. However, SlopeRAG recommended that an acoustic survey be undertaken within the multiyear RBC period to provide additional information for an updated assessment in 2017.

Following acceptance of the 2014 assessment by SlopeRAG, CSIRO undertook further work to compare 2018 biomass estimates (at the end of a three-year TAC) under constant-catch scenarios with biomass estimates from the stock assessment that used the tier 1 SESSF HSF harvest control rules (Upston & Punt 2015). The estimates of female spawning biomass at the end of the three-year period were the same for the RBCs calculated under the SESSF harvest control rules and for an annual constant-catch scenario of 513 t, at 31 per cent of unfished biomass.

The AFMA Commission subsequently agreed to a multiyear TAC of 500 t for the 2015–16, 2016–17 and 2017–18 fishing seasons. Because the stock assessment was for the eastern zone stock plus the Pedra Branca seamount (in the southern zone), it was necessary to allocate the TAC between the eastern and southern zone management units. The allocation was based on historical effort data and stock assessment allocations, and resulted in a 7 per cent allocation to the southern (Pedra Branca) zone and a 93 per cent allocation to the eastern zone. This resulted in an eastern zone agreed TAC of 465 t for the 2016–17 fishing season, of which 363 t was landed.

As recommended by SlopeRAG, an acoustic survey was undertaken in 2016. The main finding from the survey was the detection of a large body of orange roughy at St Helens Hill at the start of the survey. This body of orange roughy persisted, although it seemed to get deeper and less abundant by the end of the survey (Kloser et al. 2016).

Stock status determination

Based on the updated assessment showing the high likelihood that eastern zone orange roughy has rebuilt to above the limit reference point, eastern zone orange roughy is classified as not overfished.

For the 2016–17 fishing season, the agreed TAC was 465 t, the actual TAC was 493.6 t and the RBC was 512 t. Total landed catch was 363 t, and the weighted average discards were 3.6 t. The landed catch and discards combined was 365.6 t, which is below the RBC of 512 t (AFMA 2016b). Based on this information, eastern zone orange roughy is classified as notsubject to overfishing.

Orange roughy, southern and western zones

Catch history

The southern and western orange roughy fisheries show similar catch trends to the eastern zone fishery, with a brief period of high catches when fishing first commenced (1989 to 1992 for the eastern and southern zones; 1986 to 1988 for the western zone) and low catches thereafter (Figures 9.36, 9.38 and 9.39). The peak catch in the southern zone was 35,430 t in 1990, with subsequent catches of 14,426 t in 1991 and 16,054 t in 1992 (Figure 9.38). The western zone produced a peak historical catch of 5,128 t in 1987 (Figure 9.39).

The southern and western zone stocks were declared overfished and placed under the ORCP in 2006, when targeted commercial fishing ceased. As for the eastern zone, orange roughy catch in southern and western zones was limited to incidental catch allowances.

In the 2016–17 fishing season, 43 t of orange roughy was landed from the southern zone (57 t in 2015–16) and 22 t from the western zone (22 t in 2015–16). For 2016–17, the incidental catch allowances were 66 t for the southern zone and 60 t for the western zone. Discard estimates for orange roughy in the western zone and southern zone were not determined (Thomson & Upston 2016).

FIGURE 9.38 Orange roughy catch (CTS), southern zone, 1985 to 2016
Source: Various, including Australian Fisheries Management Authority catch disposal records
FIGURE 9.39 Orange roughy catch (CTS), western zone, 1985 to 2016
Source: Various, including Australian Fisheries Management Authority catch disposal records
Stock assessment

The assessment for the southern zone has not been updated since 2000. Standardised catch-per-shot abundance indices, using only data from vessels that had regularly fished this zone, estimated the abundance in 2001 to be 7 per cent of unfished levels (0.07SB0). Because there has been no update to the stock assessment, SERAG continues to advise an RBC of zero.

In response to the updated stock assessment for eastern zone orange roughy, which included orange roughy from Pedra Branca in the southern zone, the TAC for the southern zone was 66 t.

The western zone was most recently assessed in 2002. This assessment estimated that there was a greater than 90 per cent probability that the 2004 biomass was less than 30 per cent of the 1985 biomass. No evidence has been found of spawning aggregations in this region. A comparison of the age composition from 1994 to 1996 with that of 2004 showed a marked reduction in the modal age, indicating a heavily fished stock, although it is uncertain whether all the otolith samples were from the same stock. Because there has been no update to the assessment of the western stock, SERAG continues to advise an RBC of zero.

Noting recovery of the eastern zone orange roughy stock, and a long period of low TACs in the southern and western zones, SERAG considered that the southern and western zones may be showing some level of recovery (AFMA 2015e).

Stock status determination

Previous assessments of orange roughy in the southern and western zones indicated that the stocks were substantially depleted, to below 0.2B0. Based on the age of the stock assessments for the southern and western zones, and the time since the areas have been closed to targeted orange roughy fishing, the recovery detected in the eastern stock may suggest that similar rebuilding has occurred in the southern and western zones. This suggests increasing uncertainty around the biomass status of the southern and western zone orange roughy stocks. However, in the absence of recent data and assessments to support a hypothesis that these stocks may have rebuilt to above the limit reference point, and recognising that the characteristics of southern and western zone fisheries differ from those in the eastern zone, the southern and western zones stocks remain classified as overfished.

Given the low recent catches in the southern and western zones, and the closure of most areas deeper than 700 m to trawling, orange roughy in the southern and western zones is classified as not subject to overfishing.

Smooth oreodory (Cascade Plateau and non–Cascade Plateau (Psuedocyttus maculatus)

Smooth oreodory (Cascade Plateau and non–Cascade Plateau (Psuedocyttus maculatus) 

Line drawing: FAO

Stock structure

Little is known about the stock structure of smooth oreodory. For assessment and management purposes, smooth oreodory is treated as a single stock throughout the SESSF, excluding the Cascade Plateau and South Tasman Rise, which are managed as separate stocks.

Catch history

Smooth oreodory is targeted in aggregations around seamounts below 600 m, in the same areas as orange roughy. Oreodories have a lower value than orange roughy and historically were not the preferred species. This resulted in some discarding during the 1990s and 2000s, the period of peak orange roughy fishing.

Catches of smooth oreodory on the Cascade Plateau reached maximum levels of 275–300 t in 1997, 2000, 2001 and 2002, but have otherwise remained below 100 t (Figure 9.40). From 2004 to 2009, Cascade Plateau smooth oreodory catches declined to low levels. Only 1 t was landed in 2015–16 and there was zero catch in 2016–17. In contrast, annual smooth oreodory catches in other areas exceeded 500 t from 1990 to 1995, reaching almost 1,000 t in 1991 and peaking at 2,216 t in 1992 (Figure 9.41). Since then, smooth oreodory catches have been negligible until the 2015–16 season, when 21 t was landed. The catch increased in the 2016–17 season to 48 t. Discard rates were not determined (Thomson & Upston 2016).

FIGURE 9.40 Smooth oreodory annual catches (CTS) and fishing season TACs, Cascade Plateau, 1989 to 2016
Note: TAC Total allowable catch.
Source: Haddon 2012; Australian Fisheries Management Authority logbook records
FIGURE 9.41 Smooth oreodory annual catches (CTS) and fishing season TACs, non–Cascade Plateau, 1987 to 2016
Note: TAC Total allowable catch.
Source: Haddon 2012; Australian Fisheries Management Authority logbook records
Stock assessment

Previously, both Cascade Plateau and non–Cascade Plateau stocks were assessed using a tier 4 assessment and CPUE indices (Figures 9.42 and 9.43). In 2015, a tier 5 approach was introduced in response to work on alternative stock assessment options for data-poor fisheries (Haddon et al. 2015). SlopeRAG (AFMA 2015e, f) recommended using a depletion-based stock reduction analysis (DBSRA) and a weight-of-evidence approach to develop an RBC for the non–Cascade Plateau smooth oreodory stock (Haddon 2015). Using this method, the yield level predicted to be sustainable is at least partly dependent on the median value selected for the expected state of depletion in the final year of the analysis. Using the DBSRA in this manner for the non–Cascade Plateau smooth oreodory stock, and assuming it is at the target depletion level of 0.48B0, it was determined that a catch of 90 t should prevent the stock from falling below the limit reference point of 20 per cent (0.2B0) and would keep the stock above 0.35B0 at least 90 per cent of the time.

The assumed current stock depletion level of 0.48B0 is considered reasonable, given that almost all the stock is deeper than 700 m. Noting that the TAC of 23 t was somewhat arbitrary and that there are no sustainability issues, SlopeRAG recommended an RBC of 90 t in the non–Cascade Plateau for the 2016–17 fishing season and that the large change–limiting rule not be applied when calculating the TAC.

For smooth oreodory in the Cascade Plateau, previous assessments concluded that the standardised CPUE has remained above the target level since 1996 (Haddon 2012; Figure 9.42). However, this estimate was uncertain as a result of the low catch (that is, catches less than 10 t). SlopeRAG concluded that recent fluctuations in CPUE for this species are probably due to uncertainty resulting from low catches, and do not reflect changes in biomass (Morison et al. 2013). Catches of less than 10 t were considered to have little effect on stock biomass, and SlopeRAG recommended that the tier 4 assessment be suspended until catches increase above this level (AFMA 2013a).

FIGURE 9.42 Standardised CPUE for smooth oreodory, Cascade Plateau, 1994 to 2011
Notes: CPUE Catch-per-unit-effort. Standardised CPUE after 2011 is not shown because there was no new tier 4 assessment. Catches of smooth oreodory are now so low that catch rates are unlikely to provide reliable indices of abundance.
Source: Haddon 2012
FIGURE 9.43 Standardised CPUE for smooth oreodory, non–Cascade Plateau, 1987 to 2011
Notes: CPUE Catch-per-unit-effort. Standardised CPUE after 2011 is not shown because there was no new tier 4 assessment. Catches of smooth oreodory are now so low that catch rates are unlikely to provide reliable indices of abundance.
Source: Haddon 2012
Stock status determination

CPUE has always remained above the target for the Cascade Plateau stock. Despite the aggregating nature of the species and the fact that low catches mean that CPUE is unlikely to be a reliable indicator of abundance, it is unlikely that recent low catches have resulted in any substantial change in abundance. Similarly, while the DBSRA does not estimate biomass, it assumed that the current depletion level of the stock is 0.48B0, which is a reasonable assumption given that almost all the stock is deeper than 700 m. Therefore, the smooth oreodory (Cascade Plateau and non–Cascade Plateau) stocks are both classified as not overfished.

The DBSRA for non–Cascade Plateau smooth oreodory produced an RBC of 90 t, and is likely to be a more reliable indicator of the sustainable catch level than the previous TAC. Catch of non–Cascade Plateau smooth oreodory was 48 t in 2016–17, well under the RBC. Similarly, as in previous years, catch of Cascade Plateau oreodory was less than 10 t, and therefore, as noted by SlopeRAG, unlikely to have any impact on the stock biomass. Given the level of catch, both stocks of smooth oreodory are classified as not subject to overfishing.

Other oreodories (warty—Allocyttus verrucosus, spikey—Neocyttus rhomboidalis, rough—N. psilorhynchus, black—A. niger, other—Neocyttus spp.)

Other oreodories (warty—Allocyttus verrucosus, spikey—Neocyttus rhomboidalis, rough—N. psilorhynchus, black—A. niger, other—Neocyttus spp.) 

Line drawing: FAO

Stock structure

The mixed oreodory multispecies quota includes warty oreodory, spikey oreodory, rough oreodory and black oreodory. Nothing is known about the stock structure of the oreodory species in this multispecies quota. They are benthopelagic species that are caught mainly below 600 m. For assessment and management purposes, they are treated as a single stock in the SESSF (Morison et al. 2013).

Catch history

Catch peaked in 1990 at 980 t, but has since declined to around 100 t in recent years and was 108 t in 2016–17 (Figure 9.44).

FIGURE 9.44 Other oreodories annual catches (CTS) and fishing season TACs, 1986 to 2016
Note: TAC Total allowable catch.
Source: Haddon 2013a; Australian Fisheries Management Authority logbook records

Stock assessment

Other oreodories have historically been caught as a byproduct of fishing for orange roughy. Closure of substantial areas deeper than 700 m (except the Cascade Plateau) to all trawling in 2007 under the ORCP (AFMA 2006) reduced the opportunity to target oreodories.

The most recent tier 4 assessment for other oreodories was updated in 2013. The assessment was based only on data from areas currently open to the fishery and used the revised target reference period of 1993 to 2001 (Haddon 2013a; Morison et al. 2013). Standardised CPUE declined steadily from 1998 to 2006, but has since stabilised, remaining near the target CPUE (which is half the average CPUE over the reference period 1993 to 2001; Figure 9.45). Although the tier 4 assessment has not been updated, recent standardised CPUE from 2012 to 2015 indicates very low CPUE indices, and a trend is not apparent (Sporcic & Haddon 2016).

Using the 2013 tier 4 assessment, the RBC for other oreodories for the 2013–14 fishing season was estimated at 132 t (Morison et al. 2013). A three-year multiyear TAC was implemented at this level (132 t for the 2013–14 and 2014–15 fishing seasons) (AFMA 2014b). After consideration of discards, the RBC and resulting TAC for the 2016–17 season were both 128 t (AFMA 2016b).

FIGURE 9.45 Standardised CPUE for other oreodories, 1986 to 2012
Notes: CPUE Catch-per-unit-effort. Standardised CPUE after 2012 is not shown because there has been no new tier 4 assessment.
Source: Haddon 2013a

Stock status determination

Although oreodories are generally considered to be a byproduct of other deepwater fisheries, and much of the deepwater habitat is now closed, catches of these species declined substantially before closures were implemented. It is likely that there was substantial but unquantified discarding during the peak of the orange roughy fishery from 1989 to 1992. However, improving the basis for assessing the status of other oreodories is a low priority, given the protection afforded by current deepwater closures. The latest tier 4 assessment (Haddon 2013a) and recent standardised CPUE (Sporcic & Haddon 2016) indicate that recent average CPUE has remained stable near the target reference level since about 2005. Most (89 per cent) of the catch is reported as spikey oreodory (Sporcic 2015), so the tier 4 assessment largely reflects the status of spikey oreodory. However, there is some uncertainty about the reliability of standardised CPUE as an indicator of biomass for this highly aggregating and multispecies stock.

Because CPUE has remained stable near the target level and catches have remained near RBCs, other oreodories are classified as not overfished. The agreed and actual TACs for the 2016–17 fishing season were both 90 t, and the RBC was 128 t. Total landings were 108 t, and no estimate of discards was reported. The total fishing mortality of 108 t is below the RBC of 128 t; therefore, the stock is classified as not subject to overfishing.

Pink ling (Genypterus blacodes)

Pink ling (Genypterus blacodes) 

Line drawing: Rosalind Poole

Stock structure

Clear and persistent differences are seen between the eastern and western areas for pink ling in catch-rate trends, and size and age (Morison et al. 2013). This indicates that there are either two separate stocks, or that exchange between eastern and western components of the stock is low and they should be managed as separate stocks. Although genetic variation between eastern and western pink ling has not been found (Ward et al. 2001), the persistent differences in other biological characteristics and catch-rate trends have resulted in pink ling being assessed as separate stocks east and west of longitude 147°E since 2013.

Catches of pink ling are managed under a single TAC. However, AFMA has management arrangements in place to constrain catches of the eastern stock to the eastern catch limit.

Catch history

Combined eastern and western catches of pink ling increased steadily from the start of the fishery in about 1977 to reach a peak of 2,412 t in 1997 (Figure 9.46). Despite TACs continuing to increase from 1997 to 2001, catches declined steadily to about 1,800 t in 2004. From 2004–05 to 2013–14, pink ling catches were limited by the TAC. Commonwealth landed catch in the 2016–17 fishing season was 912.5 t. The weighted average discards between 2012 and 2015 were 32.4 t (Thomson & Upston 2016).

Pink ling is significantly under-reported in logbooks—according to AFMA catch disposal records, 912 t was landed in 2016–17, while only 765 t was reported in logbooks. This makes it difficult to assess the total level of fishing mortality, because logbook data provide information on the split in catch between the eastern and western stocks. In the preparation of catch data used for assessments, logbook data are scaled up to match the data in AFMA's catch disposal records. As a result, any under-reporting in logbooks does not necessarily bias stock assessments. Nonetheless, it will be important to address this discrepancy to reduce uncertainty in assigning status determinations in the future.

FIGURE 9.46 Pink ling annual catches (CTS, SHS and state combined) and fishing season TACs, 1977 to 2016
Notes: TAC Total allowable catch. Data for 2014 to 2016 do not include state data.
Source: Cordue 2013; Australian Fisheries Management Authority catch disposal records (2014 to 2016 catch data)
Stock assessment

Pink ling has been assessed using quantitative, model-based (tier 1) stock assessments since 2003. Annual integrated, age-structured assessments using catch-at-age data and standardised CPUE abundance indices were run from 2006 to 2012. During this period, assessment models have incorporated increasingly complex approaches to account for differential male and female growth, cohort-specific growth, changing selectivity, and the possibility of separate eastern and western stocks. An important change in the 2008 and 2009 assessments was the introduction of a split in the CPUE series in 2000 to account for an apparent change in fishing behaviour that resulted in a roughly 30 per cent decrease in catchability (see Morison et al. 2013).

In 2011, a revised assessment was proposed—removing the split in CPUE and instead fitting to CPUE data disaggregated by fishing zone—after a review identified substantial differences in the CPUE and length-frequency data between zones (Punt & Taylor 2011). The initial 2012 revised assessment fitted separate CPUE indices for each fishing zone (Punt et al. 2012) and produced a substantially more pessimistic assessment of the eastern stock, indicating that this stock was below the 0.2B0 limit. SlopeRAG did not accept the revised assessment, considering that further time was required to understand how separation of CPUE series and selectivities could produce such a different estimate of depletion for the eastern area, and to determine how CPUE indices should be weighted and combined in a non–spatially segregated model. Instead, advice in 2012 was based on an update of the 2010 base-case aggregated area model, using the disaggregated (zonal) model as one of the sensitivities to the base case. Results predicted the eastern stock to be at 0.26B0 and the western stock to be at 0.43B0 at the start of 2013 (Morison et al. 2013).

The 2012 assessment (Punt et al. 2012) was updated in 2013. In addition, industry contracted an alternative assessment by Cordue (2013). Comparison of results of initial exploratory runs using both sets of software resulted in changes to the specifications of both models to make them similar. These changes included retaining separate eastern and western stocks; modelling cohort-specific growth and time-varying selectivity; modelling a change in catch rates from 1999 to 2000 (when ling quota was consolidated onto fewer vessels), but using three vessels whose behaviour did not appear to change to link catch rates across these time blocks; and using the weighting approach recommended by Francis (2011) to down-weight length and age-frequency data, and up-weight CPUE indices.

Probability (Markov chain Monte Carlo) analysis for the eastern stock provided estimates of probabilities around results (Cordue 2013). SlopeRAG agreed to use this as the base-case model for providing advice. Results of this model indicated the biomass of the western pink ling stock to be stable at around 58 per cent of the unfished biomass, ranging from 41 to 86 per cent in the probability analyses. The biomass of the eastern pink ling stock was estimated to be around 25 per cent of the unfished biomass, ranging from 17 to 38 per cent, and trending upwards (Cordue 2013). This model estimated an RBC for eastern pink ling of 122 t (although highly uncertain, ranging from 0 to 500 t) and an RBC for the western stock of 807 t (range 430–1,710 t), with a long-term yield of 661 t. Because of the amount of effort required for such an assessment and the availability of projections with associated probabilities, SlopeRAG concluded that there was little additional benefit from updating the assessment every year, and recommended three-year TACs at RBC levels of 122 t and 661 t for the east and west, respectively (AFMA 2013a).

Because of industry concerns that it would be difficult to constrain eastern pink ling catches to this low level (given that ling are caught as bycatch during targeting of a number of other species in the CTS), Cordue (2013) provided a table of projections of future eastern pink ling biomass under a range of constant-catch scenarios, from 0 to 500 t, together with probability estimates of stock status in relation to target and limit reference levels (Table 9.3).

TABLE 9.3: Base-case 2013 stock assessment performance indicators for eastern pink ling, showing stochastic projections at a range of future constant catches
Annual
catch (t)
B2015/B0B2020/B0Probability
B2015<0.2B0
Probability
B2020<0.2B0
Rebuild year
00.330.560.0102019
2500.300.440.0402022
3000.300.420.050.012024
3500.290.390.070.022026
4000.280.370.090.042029
4500.280.350.110.072034
5000.270.320.140.112047

Notes: B2015/B0 Predicted biomass ratio in 2015. B2020/B0 Predicted biomass ratio in 2020. B2015<0.2B0 Biomass below 20 per cent B0 in 2015. B2020<0.2B0 Biomass below 20 per cent B0 in 2020. Rebuild year is the projected year for rebuilding to 48 per cent B0.
Source: Cordue 2013

These projections indicate that, under the Cordue (2013) assessment base case, there is a less than 10 per cent probability of eastern pink ling biomass in 2015 being below 20 per cent of B0 for catches below about 400 t (Cordue 2013). Based on these projections, the South East Management Advisory Committee (SEMAC) recommended that AFMA set three-year TACs, commencing in 2014–15, of 349 t for eastern pink ling and 647 t for western pink ling, if it was possible to administer separate eastern and western quotas. AFMA determined that implementing separate quotas would require a review of statutory fishing rights in the fishery. As a result, a global TAC of 996 t (1,022 t after carryover of undercaught TAC from 2013–14) was set for pink ling for the 2014–15 season, with additional controls to keep eastern catches under the RBC. These controls included a daily catch allowance for the eastern zone and a change in some concession conditions to restrict catch of pink ling from the eastern zone to 25 per cent of quota holdings. These arrangements were continued for the 2016–17 season, but with an agreed TAC of 1,144 t.

RBCs for the western stock have varied in response to the different stock assessments; they were 490 t in 2013–14, and 661 t in 2014–15 and 2015–16. Catches have remained below RBCs in the west. In contrast, RBCs for the eastern stock have declined steadily; they were 122 t in 2014–15 and 2015–16. Logbook-reported catches in the east have exceeded the eastern RBCs since 2011–12. Discarding has generally been low, and industry has reported changes in fishing practices in the east to avoid canyons and gullies known for producing higher catches of ling. These areas were closed on a voluntary basis from 2005, and by AFMA through closure direction during a number of seasons since 2009, in an effort to further reduce eastern catches.

Although TACs have been set for the two stocks combined, for the 2014–15 season, SEMAC recommended a three-year multiyear TAC to be administered as separate eastern and western TACs: 647 t for western pink ling (based on the long-term RBC estimate for this stock) and 349 t for eastern pink ling. The eastern TAC is based on results of Markov chain Monte Carlo constant-catch projections, indicating that this TAC would result in a less than 10 per cent probability of eastern pink ling being below the 0.2B0 limit reference point in 2015 (Table 9.3); it is higher than the one-year eastern RBC of 122 t recommended by SlopeRAG. Although the eastern RBCs were exceeded in 2014–15 and 2015–16, the use of a generic control rule under the SESSF harvest strategy that produces these RBCs is not needed to provide management advice on TACs when a full risk analysis is available to show the likelihood of a stock remaining above the limit reference point at least 90 per cent of the time (see Tables 9.3 and 9.4), as required by the HSP (AFMA 2009b).

The Cordue (2013) assessment was updated in 2015 (Cordue 2015). The updated assessment estimated the eastern stock biomass in 2015 to be 0.30B0 and the western stock biomass in 2015 to be 0.72B0 (Figures 9.47 and 9.48). This produced RBCs for the 2016–17 fishing season of 250 t for the east and 990 t for the west. Constant-catch scenarios were run for the eastern stock and indicated that catches in excess of 550 t led to a greater than 10 per cent probability of eastern pink ling declining to below the limit reference point by 2022; catches greater than 500 t increase the time taken to rebuild the stock to the management target (0.48B0) (AFMA 2015g). On this basis, SlopeRAG recommended that, if a TAC greater than the 2016–17 RBC was considered by the AFMA Commission, the updated table showing the range of future constant-catch scenarios should be used as the basis for determining the 2016–17 TAC. Although these constant-catch scenarios from the 2015 stock assessment were not used to determine the TAC for the 2015–16 fishing season, they may provide a more up-to-date indicator of the sustainable level of fishing mortality than the constant-catch scenarios produced by the 2013 stock assessment, and so are included (Table 9.4).

FIGURE 9.47 Estimated spawning stock biomass for western pink ling, 1970 to 2015
Source: Cordue 2015
FIGURE 9.48 Estimated spawning stock biomass for eastern pink ling, 1970 to 2015
Source: Cordue 2015
TABLE 9.4: Base-case 2015 stock assessment performance indicators for eastern pink ling, showing stochastic projections at a range of future constant catches
Annual
catch (t)
B2017/B0 B2022/B0Probability
B2017<B0
Probability
B2022<0.2B0
Rebuild year
2500.350.480.0102023
3000.330.430.020.012026
3500.310.380.040.042036
4000.300.350.070.08>2050
4500.290.320.090.13>2050
5000.270.170.150.28>2050

Notes: B2017/B0 Predicted biomass ratio in 2017. B2022/B0 Predicted biomass ratio in 2022. B2017<B0 Biomass below 20 per cent B0 in 2017. B2022<0.2B0 Biomass below 20 per cent B0 in 2022. Rebuild year is the projected year for rebuilding to 48 per cent B0.
Source: Cordue 2015

Stock status determination

The 2015 assessment indicated that the biomass of the western pink ling stock is around 72 per cent of the unfished biomass and stable, and that the biomass of the eastern pink ling stock is around 30 per cent of the unfished biomass and increasing. The 2015 assessment indicated that the eastern pink ling stock had a very low (1 per cent) probability of being below the limit reference point in 2015. On this basis, both stocks would be considered as not overfished, and so the combined stock of pink ling is classified as not overfished.

Western pink ling catches are below the western RBC levels. As a separate stock, the western stock would be classified as not subject to overfishing.

Recent catches of eastern pink ling have exceeded the RBCs produced by the 2013 and 2015 stock assessments. However, the use of a generic control rule that produces these RBCs is not needed to provide management advice on TACs when a risk analysis is available, as has been the case for the 2013 and 2015 assessments that have been used to set TACs since the 2014–15 fishing season. Catch of eastern pink ling reported in logbooks in the 2016–17 fishing season was 338 t. According to projections from the 2015 stock assessment, there is little risk to the stock over the next few years of removals up to 550 t per year. The base-case projections suggested that the stock could be rebuilt to the target reference point (B48) within one mean generation time (8.8 years). If two mean generation times are allowed for the rebuild, total removals can be 400–500 t per year. Consideration of recent fishing mortality against the constant-catch scenarios run as part of the 2013 and updated 2015 stock assessments indicates that, as a separate stock, eastern pink ling would be classified as not subject to overfishing.

Because both pink ling stocks are managed through a single TAC, their status is given a single classification, and so pink ling is classified as not subject to overfishing.

Redfish (Centroberyx affinis)

Redfish (Centroberyx affinis) 

Line drawing: FAO

Stock structure

No formal stock delineation studies of redfish have been undertaken in Australia. Tagging studies suggested a single stock of redfish off New South Wales (Morison et al. 2013). However, studies of mean length at age suggest differences in growth rates of redfish from the ‘northern' and ‘southern' sectors of the fishery off eastern Australia (Morison et al. 2013). Previous redfish assessments have therefore assumed that the fishery exploits two separate populations, with the boundary between these ‘stocks' being 36°S (immediately north of Montague Island in New South Wales) (Morison et al. 2013). However, following a review of the evidence for separate stocks, ShelfRAG considered the evidence to be insufficient; hence, the most recent stock assessment (Tuck & Day 2014) assumes a single stock combined across regions. Status is determined for a single stock in the east coast of the SESSF (zones 10, 20 and 30).

Catch history

Catches of redfish peaked in the late 1970s and early 1980s, with significant discards recorded on top of landed catch. Landed catch has decreased steadily since the late 1990s. The 2016–17 catch was 39.5 t (Figure 9.49). Estimated discards were 226 t in 2009, but have returned to lower levels in recent years, being 4 t in 2012, 29 t in 2013, 67 t in 2014 and 68 t in 2015 (Upston & Thomson 2015). Discard rates tend to be high when a pulse of recruits first enters the fishery (Klaer et al. 2014). Estimated discards are not yet available for 2016 and therefore weighted average discards are used as predictors. The weighted average discards between 2012 and 2015 were 58.99 t (Thomson & Upston 2016).

FIGURE 9.49 Redfish annual catches (CTS, SHS and state combined) and fishing season TACs, 1975 to 2016
Note: TAC Total allowable catch. Data for 2014 to 2016 do not include discards and state catch.
Source: Tuck & Day 2014; Australian Fisheries Management Authority catch disposal records (2014 to 2016 catch data)
Stock assessment

The redfish TAC has been progressively reduced since 2000. The TAC was 276 t in the 2011–12 to 2013–14 seasons, 138 t in 2014–15 and 100 t in 2014–15. Annual catches remained well below annual TACs from 2000 to around 2013 (Figure 9.49).

ShelfRAG previously assessed redfish as a tier 3 species because reliable samples of the age composition of catches are generally available. Since 2011, ShelfRAG has also taken into account tier 4 results because of concerns about ongoing declining catches and CPUE. Noting the continuing declining trend in catches and CPUE, in 2013, ShelfRAG concluded that there was a risk to the stock if the CPUE signal was correct but ignored (AFMA 2013b). Industry representatives confirmed that redfish was no longer being caught in large numbers.

The tier 3 assessment produced an RBC of 3,791 t for the 2014–15 fishing season. Because of the concerns around conflicting tier 3 and tier 4 assessments, ShelfRAG based its advice for the 2013–14 and 2014–15 seasons on an updated tier 4 analysis. This analysis was based on CPUE from zone 10 off south-eastern New South Wales (Haddon 2013a). Since 2010, the redfish tier 4 assessment has used a split reference period, covering the years 1986 to 1990 and 1999 to 2003. The intervening period is not considered representative of the fishery because it involved large trawlers catching large quantities of redfish for surimi markets.

Standardised redfish CPUE (excluding discards) has declined since 2000, with CPUE in 2012 (excluding discards) being the lowest since the series began in 1986, and the recent four-year average CPUE being below the limit reference point. An alternative tier 4 assessment, which included discard estimates, also showed a decline from 1988 to 2012, but with current average CPUE about midway between the revised targets and limits under this assessment (Haddon 2013a). Updated standardised CPUE shows that the CPUE has remained low between 2012 and 2015 (Sporcic & Haddon 2016).

The first quantitative (tier 1) assessment of redfish was undertaken in 2014 (Tuck & Day 2014). The assessment used an age- and size-structured model, and included data up to the end of 2013. The base-case model accepted by ShelfRAG predicted spawning biomass in 2015 to be 11 per cent of unexploited levels (0.11B0; Figure 9.50). Consequently, the RBC was zero. This assessment estimated that the stock should rebuild to above the limit reference point by 2018 or 2019 under total fishing mortality of up to 150 t. Projections from the assessment assume average recruitment. As a result of these projections, AFMA set an incidental catch allowance of 100 t for the 2016–17 fishing season.

The 2016–17 catch was 39.5 t. The level of discarding of redfish has been variable in recent years, and increased to 68.9 t in 2015 (Thomson & Upston 2016). The weighted average discards between 2012 and 2015 were 58.99 t (Thomson & Upston 2016).

The stock is now managed under the redfish stock rebuilding strategy 2016–2021 (AFMA 2016d), the main objective of which is to rebuild redfish to the limit reference point (0.2B0) within 27 years (one mean generation time—16.7 years [Tuck & Day 2014]—plus 10 years). The rebuilding strategy prescribes that the TAC will be set at the minimum amount required to cover the catch of redfish taken incidentally while targeting other species.

FIGURE 9.50 Estimated female spawning stock biomass for redfish, 1975 to 2013
Source: Tuck & Day 2014
Stock status determination

The recent tier 1 assessment estimated spawning stock biomass for redfish at 11 per cent of unfished levels in 2015. Based on the results of this stock assessment, redfish is classified as overfished.

Projections undertaken as part of the stock assessment suggest that redfish will recover to the limit reference point by 2018 or 2019 under a total catch of up to 150 t, assuming average recruitment (Tuck & Day 2014). Recruitment data used in the stock assessment indicated below-average recruitment between 2001 and 2009. The ageing data suggest that there have been three recent years of improved recruitment: 2011 and 2012 (Tuck & Day 2014), and 2013 (Thomson et al. 2015a). Because of this recruitment variability, and the fact that there was only one year of above-average recruitment estimated since 2001, the existence and magnitude of recruitments will need to be closely monitored over the coming years to track progress against the objectives of the rebuilding strategy.

The catch allowance for the 2016–17 fishing season was 100 t, and the RBC was 0 t. Total landings were 39.5 t, and the weighted average discards were 58.99 t, giving a total of 98.49 t. Although mortality may have been constrained to less than the incidental catch allowance, total mortality for the 2016–17 season is unknown, and recruitment is variable and uncertain. Therefore, the stock remains classified as uncertain if subject to overfishing.

Ribaldo (Mora moro)

Ribaldo (Mora moro) 

Line drawing: FAO

Stock structure

One stock of ribaldo is assumed for assessment and management purposes in the SESSF (Morison et al. 2013).

Catch history

Ribaldo is largely taken as byproduct during fishing for other species; only 5 per cent of the catch is considered to be targeted (Klaer et al. 2013). Similar proportions of the annual catch are taken by trawl and line. Historical catches increased from low levels in 1990 to a peak of more than 200 t in 2003. Catches dropped in 2005 to about 100 t, following implementation of a TAC (Figure 9.51). Landed catches decreased from 134 t in 2014–15 to 90 t in 2015–16. The Commonwealth landed catch in the 2016–17 fishing season was 87.7 t. The weighted average discards between 2012 and 2015 were 8.6 t (Thomson & Upston 2016).

FIGURE 9.51 Ribaldo annual catches (CTS and SHS) and fishing season TACs, 1986 to 2016
Notes: TAC Total allowable catch. Data for 2013 to 2016 do not include discards.
Source: Haddon 2013a; Australian Fisheries Management Authority catch disposal records (2013 to 2016 catch data)
Stock assessment

Ribaldo is assessed as a tier 4 stock using trawl CPUE (Figure 9.52; Morison et al. 2013). Ribaldo fits the criteria agreed by the Southern and Eastern Scalefish and Shark Fishery Resource Assessment Group for secondary species, and SlopeRAG has therefore provided advice on the RBC from the tier 4 assessment using the B40 target reference point (Morison et al. 2013).

The most recent tier 4 assessment was revised in 2013 with CPUE data to 2012, and results were provided for both the secondary species B40 target and a B48 target (Haddon 2013a). Calculations used the period 1995 to 2004 as the reference period (when catches first approached 100 t). Given the lightly exploited nature of the fishery during the reference period, the target CPUE was calculated by dividing the average reference period CPUE by 2, to reflect the likely change in CPUE that would occur as the fishery became fully exploited. Trawl catch rates have been relatively stable since 2000, and auto-longline catch rates have been stable since 2005. Both are above the target level. Throughout this period, catches have remained below the established TACs and below RBCs. The 2013 analysis produced an RBC of 355 t using the B40 target (Haddon 2013a). SlopeRAG recommended a three-year RBC of 355 t, with a review if 70 per cent or more of the TAC is caught, if trawl CPUE changes by 50 per cent or more, or if there is a significant change in the proportion of catch by the line sector (AFMA 2013a). SlopeRAG also recommended that a discount factor not apply because of the existing closures for both trawl and auto-longline methods. After applying the large change–limiting rule, AFMA implemented a three-year multiyear TAC of 252 t for 2014–15, and 355 t for 2015–16 and 2016–17.

FIGURE 9.52 Standardised CPUE for ribaldo, 1986 to 2012
Notes: CPUE Catch-per-unit-effort. Standardised CPUE after 2012 is not shown because there has been no new tier 4 assessment.
Source: Haddon 2013a
Stock status determination

Standardised CPUE has remained stable or increased, and has been above the target level for the past decade. Ribaldo is therefore classified as not overfished.

For the 2016–17 fishing season, the agreed TAC was 355 t, the actual TAC was 389 t and the RBC was 355 t. Total landed catch was 87.7 t, and the weighted average discards were 8.6 t. The landed catch and discards combined was 96.3 t, which is below the RBC of 355 t. The stock is therefore classified as not subject to overfishing.

Royal red prawn (Haliporoides sibogae)

Royal red prawn (Haliporoides sibogae) 

Line drawing: FAO

Stock structure

Royal red prawn is widespread, occurring in depths of 350 to 550 m in the Indian and western Pacific oceans. In Australia, royal red prawn is caught off New South Wales, Queensland and Western Australia between latitudes 10°S and 36°S. Little is known of the stock structure in eastern Australia. Because most of the Australian catch is taken off the New South Wales coast between Port Stephens and Ulladulla, for assessment and management purposes, these populations are assumed to comprise a single stock (Morison et al. 2013).

Catch history

Catch of royal red prawn fluctuated around 500 t per year during the 1990s and early 2000s, before declining and stabilising at around 100–200 t in recent years (Figure 9.53). Catch has been below the TAC in recent years, which can largely be attributed to limited availability of processing facilities for this species and low market demand (Morison et al. 2013). The catch of royal red prawn in the 2016–17 fishing season was 126.8 t. The weighted average discards between 2012 and 2015 were 1.9 t (Thomson & Upston 2016).

FIGURE 9.53 Royal red prawn annual catches (CTS and state combined) and fishing season TACs, 1986 to 2016
Note: TAC Total allowable catch. Data for 2013 to 2016 do not include discards and state catch.
Source: Haddon 2013a; Australian Fisheries Management Authority catch disposal records (2013 to 2016 catch data)
Stock assessment

The RBC for royal red prawn is based on the most recent tier 4 assessment (Haddon 2013a) and harvest control rules, with the limit CPUE (CPUELIM) specified at 40 per cent of the target CPUE (CPUETARG). The assessment indicates that the average standardised CPUE for the four years to 2012 was at the target reference point (Figure 9.54). ShelfRAG determined the stock suitable for a three-year RBC, with the implementation of a breakout rule based on a 50 per cent change in CPUE. Based on the 2013 assessment, ShelfRAG proposed a three-year RBC of 393 t, and AFMA recommended a multiyear TAC of 388 t for the 2014–15 to 2016–17 fishing seasons. After deduction of discard estimates and state catch, the agreed TAC was set at 387 t for the 2016–17 fishing season.

Some concerns about using a tier 4 analysis for this stock have been expressed by ShelfRAG because targeting of royal red prawn is market driven (Morison et al. 2013). Such practices may influence CPUE and the tier 4 assessment.

FIGURE 9.54 Standardised CPUE for royal red prawn, 1986 to 2012
Notes: CPUE Catch-per-unit-effort. Standardised CPUE after 2012 is not shown because there has been no new tier 4 assessment.
Source: Haddon 2013a
Stock status determination

The recent average CPUE is marginally below the target reference point. Size structure has been relatively stable, and catches have been below the RBC in recent years. As a result, this stock is classified as not overfished.

For the 2016–17 fishing season, the agreed TAC was 387 t, the actual TAC was 417 t and the RBC was 393 t. Total landed catch was 126.8 t, and the weighted average discards were 1.9 t. The landed catch and discards combined was 128.8 t, which is below the RBC of 393 t. The stock is therefore classified as not subject to overfishing.

Silver trevally (Pseudocaranx georgianus)

Silver trevally (Pseudocaranx georgianus) 

Line drawing: FAO

Stock structure

Silver trevally is found in Australian and New Zealand waters. In Australia, they range from northern New South Wales, around southern Australia to Western Australia. Little is known of the stock structure. Preliminary research suggests that silver trevally off south-eastern Australia represents a single stock that is distinct from the North Island of New Zealand fishery (Rowling & Raines 2000). The growth rate of the Australian stock of silver trevally is slower than that reported for the New Zealand stock; however, it matures comparatively early, at about two years of age, with spawning occurring throughout summer (Morison et al. 2013).

Catch history

High catch rates between 1989 and 1991, with a peak catch in 1990 of 1,588 t, were the result of efficient vessels entering the fishery in 1989 (Haddon 2013a). Catch has since declined (Figure 9.55). Catch decreased from 93 t in 2014–15 to 72 t in 2015–16 out of the 615 t multiyear TAC. The Commonwealth landed catch in the 2016–17 fishing season was 52.8 t. Silver trevally is also a popular target for recreational fishers off south-eastern Australia; the recreational catch in New South Wales was estimated to be around 27 t in 2013–14 (West et al. 2015). The weighted average discards between 2012 and 2015 were 19.58 t (Thomson & Upston 2016).

FIGURE 9.55 Silver trevally annual catches (CTS, SHS and state combined) and fishing season TACs, 1986 to 2016
Notes: TAC Total allowable catch. Data for 2013 to 2016 exclude discards and state data.
Source: Haddon 2013a; Australian Fisheries Management Authority catch disposal records (2013 to 2016 catch data)
Stock assessment

The 2013 tier 4 assessment (Haddon 2013a) used the reference period 1992 to 2001, since high catch rates before 1992 (Figure 9.56) were not considered to be sustainable (Haddon 2013b). CPUE declined from 1993, to be near the limit by 2002. The fishery exhibited a general trend of increasing CPUE between 2003 and 2010, but CPUE has since declined. Standardised CPUE using catch data to 2012 indicates that recent CPUE decreased to near the target (Haddon 2013a; Figure 9.56). The most recent tier 4 assessment (Haddon 2013a) estimated four-year average CPUE to be near the target level. This assessment estimated a one-year RBC of 858 t and a three-year RBC of 791 t; ShelfRAG recommended a three-year RBC (AFMA 2013b). AFMA subsequently set a three-year multiyear TAC of 615 t for the 2013–14 to 2015–16 seasons. After deduction of state catches and discards, the 2015–16 TAC was 602 t.

The establishment of Batemans Marine Park in June 2007 has affected the estimation of silver trevally RBCs because historical catch data from within the park boundaries are included in the target catch range component of the RBC calculation, but the CPUE analyses do not include historical activities in this area. The RBC derived from the 2013 tier 4 assessment (Haddon 2013a) considered catch rates from both within and outside the marine park, and found little difference in the RBC estimate. Nonetheless, ShelfRAG recommended waiving the default tier 4 discount factor of 15 per cent of the RBC, on the basis that the marine park provides sufficient precaution as a refuge for spawning adults and juveniles across a significant portion of the species' distribution (AFMA 2013b). However, adult silver trevally are highly mobile, and the inclusion of past marine park catches in RBC calculations assumes that silver trevally in these areas are fully available to fisheries outside the park.

Before 2010, most of the silver trevally catch was taken in state waters outside the SESSF (Morison et al. 2013). The closure of silver trevally trawling grounds within Batemans Marine Park, and the New South Wales buyout of state fishing businesses before 2007, have resulted in a sharp decline in New South Wales state catch (Morison et al. 2013).

FIGURE 9.56 Standardised CPUE for silver trevally, 1986 to 2012
Notes: CPUE Catch-per-unit-effort. Standardised CPUE after 2012 is not shown because there has been no new tier 4 assessment.
Source: Haddon 2013a
Stock status determination

The four-year average standardised CPUE used for the most recent tier 4 assessment is above the target reference level. As a result, silver trevally is classified as not overfished.

For the 2016–17 fishing season, the agreed TAC was 588 t, the actual TAC was 645 t and the RBC was 791 t. The landed catch was 52.8 t, and the weighted average discards were 19.5 t. The landed catch and discard, combined was 72.3 t, which is below the RBC of 791 t. The stock is therefore classified as not subject to overfishing.

Silver warehou (Seriolella punctata)

Silver warehou (Seriolella punctata) 

Line drawing: FAO

Stock structure

A study has been completed on the stock structure of silver warehou using genetics (mitochondrial DNA), morphology, otolith shape and otolith microchemistry (Robinson et al. 2008). Results did not indicate the presence of separate stocks east and west of Bass Strait, although there were indications of some structuring around Tasmania. This study, together with other information, suggests that silver warehou should be considered as a single biological stock in the SESSF (Morison et al. 2013).

Catch history

Silver warehou is caught entirely by trawl in the CTS and has been a targeted species throughout most of the history of the fishery. Silver warehou catches steadily increased from the start of the fishery in 1980 to peaks of 4,450 t in 2002 and 4,435 t in 2004 (Figure 9.57). Catches subsequently declined to 370 t out of the 2,329 t TAC in 2014–15 and 276 t out of the 2,417 t TAC in 2015–16. The Commonwealth landed catch in the CTS for the 2016–17 fishing season was 311 t (the total landed catch in the SESSF was 360 t). The weighted average discards between 2012 and 2015 were 26.66 t (Thomson & Upston 2016).

FIGURE 9.57 Silver warehou annual catches (CTS, SHS and state combined) and fishing season TACs, 1980 to 2016
Notes: TAC Total allowable catch. Data for 2015 and 2016 do not include discards and state catch.
Source: Thomson et al. 2015b; Australian Fisheries Management Authority catch disposal records (2016 catch data)

Stock assessment

Silver warehou has been managed under tier 1 of the SESSF HSF since the HSF was introduced. The 2009 model-based assessment (Tuck & Fay 2010) predicted the spawning stock biomass in 2010 to be 48 per cent of unfished levels and was used as the basis for a three-year TAC of 2,566 t, commencing in 2010–11. SlopeRAG developed breakout rules to trigger a review of this three-year TAC, including whether the most recent observed value for the standardised CPUE falls outside the 95 per cent confidence interval of the value predicted by the most recent stock assessment (AFMA 2013a).

This breakout rule was triggered in 2012, resulting in an update of the model-based assessment, including updates of catch, discard, length, age and catch-rate data (Day et al. 2012). The 2012 assessment was inconsistent with the CPUE decline over the past two years, instead estimating a biomass increase. This indicated that the model may be optimistic in its forward CPUE estimates. SlopeRAG concluded that the CPUE breakout rule was likely to be triggered again as a result of this lack of fit to the CPUE (AFMA 2013a). However, the base-case assessment projected that the 2013 spawning stock biomass would be 0.47B0, indicating that there was little immediate concern about stock status. Following SlopeRAG's recommendations, a three-year TAC of 2,329 t was established based on this assessment, starting in 2013–14.

The CPUE breakout rule was again triggered in 2013 and 2014, as expected. SlopeRAG advised against repeating a full stock assessment, because there appeared to be a retrospective problem with the assessment, causing it to repeatedly overestimate biomass in recent years. SlopeRAG recommended that the multiyear TAC continue, and that work be done to determine the reason for the retrospective pattern in analyses before a further update of the silver warehou assessment (AFMA 2013a).

A tier 1 assessment in 2015 (Thomson et al. 2015b) used updated catch, discard, CPUE, length and age data. The updated assessment projected the 2016 spawning biomass to be 0.4B0 (Figure 9.58), and produced a 2016–17 RBC of 1,958 t and a long-term yield of 2,281 t. However, these scenarios assume average recruitment; recruitment has been below average since 2003.

In the initial tier 1 assessment, sensitivities were run using a ‘poor' recruitment scenario (the average of a recent five-year period of poor recruitment) and a ‘very poor' recruitment scenario (the average of the worst three of these five years). A constant catch of 381 t was used in projections under these scenarios, based on the volume of recent landed catches of silver warehou. Neither of these low-recruitment scenarios indicated that the stock would approach the target biomass by 2020 at a catch of 381 t, and the very poor recruitment scenario indicated a decline in spawning biomass to a depletion level below 40 per cent in 2020 (AFMA 2015f). This indicates that, at tested catch levels, future increases in stock are dependent on levels of future recruitment increasing to above the low-recruitment scenarios assumed for these projections. SlopeRAG (AFMA 2015f) noted that the recent series of sequential poor recruitments indicates that there is a risk that silver warehou recruitment may be serially correlated and that future recruitment may remain low.

SlopeRAG (AFMA 2015f) noted that, if one of the objectives of the next silver warehou multiyear TAC is to increase the biomass from the current estimated level, a catch below 600 t is recommended. Recognising the constraints of the large change–limiting rule, SlopeRAG recommended stepping down to the poor-recruitment scenario RBC of 604 t in two years (AFMA 2015h). Consequently, and subject to the change-limiting rule, the TAC for the 2016–17 fishing season was set at 1,209 t.

FIGURE 9.58 Estimated spawning stock biomass for silver warehou, 1980 to 2014
Source: Thomson et al. 2015a
Stock status determination

The 2015 stock assessment predicted spawning biomass in 2016 to be 0.4B0. The target reference point is 0.48B0. Silver warehou therefore remains classified as not overfished.

For the 2016–17 fishing season, the agreed TAC was 1,209 t, the actual TAC was 1,449 t and the RBC was 1,958 t. Total landed catch in the CTS was 311.7 t, and the weighted average discards were 26 t. The landed catch and discards combined was 337.7 t, which is below the RBC of 1,958 t. This total fishing mortality was also below the low-recruitment constant-catch scenario that produced an updated 2016–17 RBC of 604 t. The stock is therefore classified as not subject to overfishing.

9.3 Economic status

Key economic trends

The CTS and the SHS contributed approximately 57 per cent of total SESSF GVP ($73.25 million) in 2015–16. From 2005–06 to 2012–13, real GVP for the two sectors averaged $67.37 million (in 2015–16 dollars; Figure 9.59). By 2013–14, it had fallen, and has since remained, below $50.00 million. Since 2005–06, the decline in the value of orange roughy and blue grenadier catches were the key drivers of the reduction in scalefish GVP. In 2005–06, orange roughy catches were valued at $7.40 million, and blue grenadier catches were valued at $9.21 million. By 2013–14, the GVP of orange roughy catches had declined to $819,000, and blue grenadier catches had declined to $6.66 million. For orange roughy, this declining trend was due to TAC reductions to recover stocks. In terms of value during 2015–16, the mix of species caught was dominated by tiger flathead ($18.17 million; 39 per cent of the total GVP) and pink ling ($4.68 million; 10 per cent).

FIGURE 9.59 Real GVP, by key species, for the CTS and SHS, 2005–06 to 2015–16
Note: GVP Gross value of production.

Estimates of the net economic returns (NER) associated with scalefish catches for the CTS and the SHS combined are not available, because ABARES undertakes economic surveys of the CTS separately from the SHS (which is surveyed as part of the GHTS). However, with respect to value, the CTS accounts for the majority of the scalefish catch. Estimates of NER for the CTS have been positive since 2005–06, increasing from $1.83 million in 2005–06 to $7.43 million in 2010–11, then falling to $1.82 million in 2013–14 (2015–16 dollars; Figure 9.60). The reduction in NER since 2010–11 has been due to increasing costs, and a fall in the price of fish between 2012–13 and 2013–14 (Skirtun & Green 2015). Despite the reduction in GVP, a 20 per cent fall in the price of fuel—a major component of costs for trawl vessels, in particular—is likely to have supported positive NER.

The economic performance of the CTS has improved overall since 2003–04, but has declined since a peak in 2010–11. A profit decomposition of the CTS (Skirtun & Vieira 2012) suggested that output prices, followed by more productive use of capital (boat and equipment), have been the key drivers of the overall improvements in profitability. The contribution from improved capital productivity is likely to have been partly associated with the Securing our Fishing Future structural adjustment package, which resulted in removal of around half the boat statutory fishing rights in the CTS. The voluntary tender design of the structural adjustment package is likely to have resulted in the removal of the least efficient vessels from the sector, leading to an increase in the average capital productivity per vessel (Vieira et al. 2010). Productivity declined 8 per cent between 2011–12 and 2012–13. This decline has contributed to the decline in NER since 2010–11 (Figures 9.60 and 9.61; Skirtun & Green 2015). Preliminary work on the efficiency of vessels operating in the CTS supports the hypothesis that efficiency improved following structural adjustment, but declined from 2010–11 to 2012–13, so that the median vessel was operating at only 64 per cent efficiency (Green 2016). The research also indicated that the potential productivity of vessels in the CTS has declined since 2008–09, but further research is required to determine the cause.

FIGURE 9.60 NER for the CTS, 2003–04 to 2013–14
Notes: NER Net economic returns. Results for 2013–14 are preliminary, non–survey based estimates.
FIGURE 9.61 Revenue and costs for the CTS, 2003–04 to 2013–14
Note: Results for 2013–14 are preliminary, non–survey based estimates.
Source: Skirtun & Green 2015

Management arrangements

Both the CTS and the SHS are managed under ITQs. TACs are set for key target species for each fishing season and allocated to quota holders. This form of management promotes efficiency, because it allows operators to harvest with greater flexibility (with fewer restrictions on inputs), and often results in quota being acquired by the most efficient and profitable operators. ITQ management in the SESSF has used multiyear TACs for some stocks, which are usually set for three years. In recent years, the latency in key scalefish species in the SESSF has increased (Skirtun & Green 2015). This has coincided with falls in NER in 2013–14, largely as a result of lower prices for key species. The appearance of deteriorating conditions in 2013–14—in the context of a multispecies fishery—and increasing latency may indicate a need to review MEY targets and TACs.

Historically, proxy targets have been set at the species level and have not taken account of interactions between species caught in the sector. If management settings are based on the MEY of individual species, achieving the objective for one species may be constrained by the management settings targeting the MEY of another species. Several resource assessment groups have begun to look at target biomass levels below individual BMEY for these secondary species. Vieira et al. (2013) have provided advice on the potential fishery-wide economic benefits that could be derived from setting MSY-based targets for secondary species in the SESSF. Alternative MSY-based 0.4B0 targets have been approved by AFMA for ocean perch, ribaldo and john dory.

Performance against economic objective

With the exceptions listed above, all species groups under quota in the SESSF are managed under a harvest strategy that targets BMEY, the biomass level that is likely to be associated with MEY. Management has generally pursued BMEY by using a proxy target reference point (most often 0.48B0). Tiger flathead, blue grenadier, pink ling and blue-eye trevalla accounted for 59 per cent of total GVP in both sectors in 2015–16. The biomass of these species, relative to the respective BMEY targets, therefore provides an indication of performance against the objective of maximising NER.

Of the four key species, only tiger flathead has a quantitatively estimated species-specific MEY target, at 0.38B0. This was adjusted to 0.40B0 to take a more precautionary approach (Morison et al. 2013; Figure 9.17). At 42 per cent of unfished spawning biomass (0.42SB0), the estimated biomass of tiger flathead in 2016 was above the MEY target (Day 2017). Moreover, the biomass has been increasing since 2008. Similarly, at 0.77B0, the biomass estimate for blue grenadier in 2013 was above the target reference point (0.48B0) (Tuck 2013; Figure 9.8). This implies that NER are not constrained by these two stocks and improvements are possible if the species were fished down towards BMEY. However, lower prices in recent years are likely discouraging participation by the factory vessels best suited to exploiting the stock. In 2015, an updated stock assessment estimated that the western pink ling stock was 0.72B0, which is significantly above the target reference point; however, in the east, the stock was 0.30B0, which is below the target reference point. The stock of blue-eye trevalla is between the limit and reference points. With the exception of eastern pink ling and blue-eye trevalla, it can be concluded that these key species are being managed at levels that are not below BMEY targets. However, the disinclination of fishers to significantly fish-down blue grenadier suggests that the 0.48B0 proxy may not be aligned with MEY. Alternatively, this disinclination may be the result of unusually low prices and participation that will be resolved in the medium term.

Blue-eye trevalla
Tamre Sarhan, AFMA

Two other species considered here are silver warehou and orange roughy. Silver warehou accounted for 1 per cent of scalefish GVP in 2015–16, but had accounted for up to 8 per cent immediately after the adoption of the HSP. An assessment update in 2015 projected silver warehou biomass to be 0.4B0 in 2016, which is below the target of 0.48B0. However, latency is high, with only 26 per cent of the 2016–17 TAC caught by fishers. Whereas orange roughy accounted for 5 per cent of the value of the scalefish catch in 2015–16, it accounted for more than 50 per cent in the early 1990s. Catches at that time were associated with overfishing, and two of the four orange roughy stocks are currently assessed as overfished. Although all four orange roughy stocks are classified as ‘not subject to overfishing', rebuilding of these stocks is expected to be slow. The resumption of targeted orange roughy fishing in the eastern zone means that orange roughy is now the fourth most valuable stock in the CTS and, subject to continued rebuilding, may play a larger role in the economic performance of the fishery.

Overall, NER in the CTS have been positive since 2005–06, although there has been a decline since 2010–11. Combined with the reductions in vessel numbers and associated increases in economic productivity, this suggests that, overall, the CTS has moved closer to MEY since 2005–06. Although preliminary estimates for 2013–14 show some deterioration in economic performance, falls in the price of fuel will likely have contributed positively to NER. Additionally, the estimated current biomasses of at least three of the four most valuable species are close to the respective BMEY targets. This indicates that the economic status of the CTS is positive and has substantially improved since the adoption of MEY targeting, despite falls since 2010–11. Economic status in the long term will be improved if orange roughy stocks can continue to rebuild. The large amount of uncaught blue grenadier quota suggests that NER can be improved by fishing down the stock. However, low prices are likely deterring participation by factory vessels best suited to exploiting the stock.

Economic performance could improve further if approaches to setting MEY-based target reference points were improved. In particular, it may be beneficial to develop ways of setting target reference points for a multispecies fishery and derive cost-effective estimates of species-specific BMEY for some of the more valuable species.

There is potential for vessels to improve their ability to use existing technology more efficiently—the median vessel operated at only 64 per cent efficiency in 2012–13 (Green 2016). Improvements in efficiency would likely improve NER. The same research indicates that potential productivity of the fishery has also declined since 2008–09; more research is required to determine the reasons for this. If it is the result of management changes, the management objectives served by these changes must be assessed against any associated fall in NER.

9.4 Environmental status

The environmental status of these fisheries is discussed in Chapter 8.

9.5 References

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—— 2013a, ‘Southern and Eastern Scalefish and Shark Fishery Slope Resource Assessment Group (SlopeRAG), minutes, 6–8 November 2013, Hobart', AFMA, Canberra.

—— 2013b, ‘Southern and Eastern Scalefish and Shark Fishery Shelf Resource Assessment Group (ShelfRAG), minutes, 25–27 September 2013, Tasmania', AFMA, Canberra.

—— 2013c, ‘Southern and Eastern Scalefish and Shark Fishery Shelf Resource Assessment Group (ShelfRAG), minutes, 4–5 November 2013, Tasmania', AFMA, Canberra.

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—— 2013e, ‘Southern and Eastern Scalefish and Shark Fishery Slope Resource Assessment Group (SlopeRAG), minutes, 23–25 September 2013, Hobart', AFMA, Canberra.

—— 2014a, ‘Southern and Eastern Scalefish and Shark Fishery Slope Resource Assessment Group (SlopeRAG), minutes, 30 October 2014, Hobart', AFMA, Canberra.

—— 2014b, ‘South East Management Advisory Committee (SEMAC) draft minutes, meeting 14, 30–31 January 2014', AFMA, Canberra.

—— 2014c, Blue warehou (Seriolella brama)stock rebuilding strategy, revised 2014, Southern and Eastern Scalefish and Shark Fishery (SESSF), AFMA, Canberra.

—— 2014d, ‘Southern and Eastern Scalefish and Shark Fishery Shelf Resource Assessment Group (ShelfRAG), minutes, 23–24 September 2014, Tasmania', AFMA, Canberra.

—— 2014e, Southern and Eastern Scalefish and Shark Fishery management arrangements booklet May 2014, AFMA, Canberra.

—— 2014f, ‘Southern and Eastern Scalefish and Shark Fishery Shelf Resource Assessment Group (ShelfRAG), minutes, 28–29 October 2014, Tasmania', AFMA, Canberra.

—— 2014g, Species summaries for the Southern and Eastern Scalefish and Shark Fishery, AFMA, Canberra.

—— 2014h, ‘Southern and Eastern Scalefish and Shark Fishery Slope Resource Assessment Group (SlopeRAG), minutes, December 2014', AFMA, Canberra.

—— 2015a, ‘Southern and Eastern Scalefish and Shark Fishery Shelf Resource Assessment Group (ShelfRAG), minutes, 23–23 September 2015, Tasmania', Shelf Resource Assessment Group, AFMA, Canberra.

—— 2015b, Eastern gemfish (Rexea solandri)stock rebuilding strategy, AFMA, Canberra.

—— 2015c, ‘Southern and Eastern Scalefish and Shark Fishery Shelf Resource Assessment Group (ShelfRAG), minutes, 28–30 October 2015, Tasmania', AFMA, Canberra.

—— 2015d, Orange roughy (Hoplostethus atlanticus)stock rebuilding strategy 2014, AFMA, Canberra.

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—— 2015g, ‘Southern and Eastern Scalefish and Shark Fishery Slope Resource Assessment Group (SlopeRAG), minutes, 25 November 2015, teleconference', AFMA, Canberra.

—— 2015h, SESSF total allowable catch recommendations for the 2016–17 fishing year, AFMA, Canberra.

—— 2016a, Southern and Eastern Scalefish and Shark Fishery management arrangements booklet April 2016, AFMA, Canberra.

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—— 2016c, Stock rebuilding strategies annual reviews. Eastern gemfish stock rebuilding strategy—annual review, SERAG meeting 2016, AFMA, Canberra.

—— 2016d, Redfish (Centroberyx affinis) stock rebuilding strategy 2016–2021, AFMA, Canberra.

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DAFF 2007, Commonwealth Fisheries Harvest Strategy: policy and guidelines, Australian Government Department of Agriculture, Fisheries and Forestry, Canberra.

Daley, R, Stevens, J & Graham, K 2002, Catch analysis and productivity of the deepwater dogfish resource in southern Australia, Fisheries Research and Development Corporation project 1998/108, CSIRO Marine and Atmospheric Research, Hobart.

Day, J 2010, ‘School whiting (Sillago flindersi) stock assessment based on data up to 2008', in GN Tuck (ed.), Stock assessment for the Southern and Eastern Scalefish and Shark Fishery 2009, part 1, AFMA & CSIRO Marine and Atmospheric Research, Hobart.

—— 2011, ‘School whiting (Sillago flindersi): exploration of fixed projected catches and a retrospective look at variability in recruitment estimates', in GN Tuck (ed.), Stock assessment for the Southern and Eastern Scalefish and Shark Fishery 2011, part 1, AFMA & CSIRO Marine and Atmospheric Research, Hobart.

—— 2012, ‘School whiting (Sillago flindersi): further exploration of fixed projected catches, potential indicators and alternative harvest strategy analyses', in GN Tuck (ed.), Stock assessment for the Southern and Eastern Scalefish and Shark Fishery 2012, part 1, AFMA & CSIRO Marine and Atmospheric Research, Hobart.

—— 2016, Tiger flathead (Neoplatycephalus richardsoni) stock assessment based on data up to 2015, CSIRO Marine and Atmospheric Research, Hobart.

—— 2017, Updated RBC calculations for tiger flathead (Neoplatycephalus richardsoni) stock assessment based on data up to 2015, CSIRO Marine and Atmospheric Research, Hobart.

—— & Klaer, N 2013, Tiger flathead (Neoplatycephalus richardsoni) stock assessment based on data up to 2012, AFMA & CSIRO Marine and Atmospheric Research, Hobart.

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Elliott, NG & Ward, RD 1994, ‘Enzyme variation in jackass morwong, Nemadactylus macropterus (Schneider, 1801) (Teleostei: Cheilodactylidae), from Australian and New Zealand waters', Australian Journal of Marine and Freshwater Research, vol. 45, no. 1, pp. 51–67.

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—— 2015, Tier 4 analyses for selected species in the SESSF (data from 1986–2014), draft version, CSIRO Oceans and Atmosphere, Hobart.

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——, Klaer, N, Wayte, S & Tuck, G 2015, Options for tier 5 approaches in the SESSF when data support for harvest strategies are inappropriate, FRDC project 2013/202, CSIRO Oceans and Atmosphere, Hobart.

Hamer, P, Kemp, J, Robertson, S & Hindell, J 2009, Use of otolith chemistry and shape to assess the stock structure of blue grenadier (Macruronus novaezelandiae) in the Commonwealth Trawl and Great Australian Bight fisheries, final report to FRDC, project 2007/020, Fisheries Research Branch, Queenscliff.

Helidoniotis, F & Moore, A 2016, Tier 1 assessment of western gemfish in the SESSF: draft, ABARES, Canberra.

Klaer, N 2013, ‘Yield, total mortality values and tier 3 estimates for selected shelf and slope species in the SESSF 2012', in GN Tuck (ed.), Stock assessment for the Southern and Eastern Scalefish and Shark Fishery 2012, part 2, AFMA & CSIRO Marine and Atmospheric Research, Hobart.

——, Day, J, Fuller, M, Krusic-Goleb, K & Upston, J 2013, Data summary for the Southern and Eastern Scalefish and Shark Fishery: logbook, landings and observer data to 2012, CSIRO Marine and Atmospheric Research, Hobart.

——, Day, J, Fuller, M, Krusic-Goleb, K & Upston, J 2014, Data summary for the Southern and Eastern Scalefish and Shark Fishery: logbook, landings and observer data to 2013, CSIRO Marine and Atmospheric Research, Hobart.

Kloser, RJ, Knuckey, IA, Ryan, TE, Pitman, LR & Sutton, C 2011, Orange Roughy Conservation Program: eastern zone surveys and trials of a cost-effective acoustic headline system, final report to the South East Trawl Fishing Industry Association, CSIRO Marine and Atmospheric Research, Hobart.

——, Green, M & Sherlock, M 2016, Orange roughy surveys of St Helens Hill and St Patricks Head with a net attached acoustic/optical system (AOS), CSIRO Marine and Atmospheric Research, Hobart.

Last, PR & Stevens, JD 2009, Sharks and rays of Australia, CSIRO Publishing, Collingwood.

Little, R 2012, ‘A summary of the spawning potential ratio (SPR), its calculation and use in determining over-fishing in the SESSF: an example with eastern gemfish', in GN Tuck (ed.), Stock assessment for the Southern and Eastern Scalefish and Shark Fishery 2011, part 2, AFMA & CSIRO Marine and Atmospheric Research, Hobart.

—— & Rowling, K 2011, ‘2010 update of the eastern gemfish (Rexea solandri) stock assessment', in GN Tuck (ed.), Stock assessment for the Southern and Eastern Scalefish and Shark Fishery 2010, part 1, AFMA & CSIRO Marine and Atmospheric Research, Hobart.

Miller, MP & Stewart, J 2009, ‘The commercial fishery for ocean leatherjackets (Nelusetta ayraudi, Monacanthidae) in New South Wales, Australia', Asian Fisheries Science, vol. 22, pp. 257–64.

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——, Knuckey, IA, Simpfendorfer, CA & Buckworth, RC 2013, South East Scalefish and Shark Fishery: draft 2012 stock assessment summaries for species assessed by GABRAG, ShelfRAG & Slope/DeepRAG, report for AFMA, Canberra.

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—— & Haddon, M 2016, Statistical CPUE standardizations for selected SESSF species (data to 2015), CSIRO Oceans and Atmosphere Flagship, Hobart.

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——, Sporcic, M, Klaer, N, Fuller, M, Krucic-Golub, K & Upston, J 2015a, Data summary for the Southern and Eastern Scalefish and Shark Fishery: logbook, landings and observer data to 2014, draft report prepared by CSIRO Wealth from Oceans Flagship for AFMA, Canberra.

——, Day, J & Tuck, G 2015b, Spotted warehou (Seriolella punctata) stock assessment based on data up to 2014: development of a preliminary base case, CSIRO Marine and Atmospheric Research, Hobart.

—— & Upston, J 2016, SESSF catches and discards for TAC purposes, 9 November 2016, report prepared by CSIRO Wealth from Oceans Flagship for AFMA, Canberra.

——, Fuller, M, Deng, R & Althaus, F 2016, Data summary for the Southern and Eastern Scalefish and Shark Fishery: logbook, landings and observer data to 2015, report prepared by CSIRO Wealth from Oceans Flagship for AFMA, Canberra.

Tuck, G 2013, Stock assessment of blue grenadier Macruronus novaezelandiae based on data up to 2012, CSIRO Marine and Atmospheric Research, Hobart.

—— & Day, J 2014, Stock assessment for redfish Centroberyx affinis based on data up to 2013, CSIRO Oceans and Atmosphere Flagship, Hobart.

—— & Fay, G 2010, ‘Silver warehou (Seriolella punctata) stock assessment based on data up to 2008', in GN Tuck (ed.), Stock assessment for the Southern and Eastern Scalefish and Shark Fishery 2011, part 1, AFMA & CSIRO Marine and Atmospheric Research, Hobart.

——, Day, J, Thomson, R & Wayte, S 2015, Development of a base-case tier 1 assessment for the western stock of jackass morwong (Nemadactylus macropterus) based on data up to 2014, report produced by CSIRO Marine and Atmospheric Research for ShelfRAG, AFMA, Canberra.

Upston, J & Punt, A 2015, Orange roughy (Hoplostethus atlanticus) eastern zone stock assessment incorporating catch data up to 2014: supplement—constant catch scenarios, AFMA & CSIRO Oceans and Atmosphere Flagship, Hobart.

—— & Thomson 2015, Integrated Scientific Monitoring Program for the Southern and Eastern Scalefish and Shark Fishery: discard estimation 2014, AFMA & CSIRO Marine Resources and Industries, Hobart.

——, Punt, A, Wayte, S, Ryan, T, Day, J & Sporcic, M 2014, Orange roughy (Hoplostethus atlanticus) eastern zone stock assessment incorporating data up to 2014, AFMA & CSIRO Oceans and Atmosphere Flagship, Hobart.

Vieira, S, Perks, C, Mazur, K, Curtotti, R & Li, M 2010, Impact of the structural adjustment package on the profitability of Commonwealth fisheries, Australian Bureau of Agricultural and Resource Economics research report 10.01, Canberra.

——, Penney, A, Hormis, M & Woodhams, J 2013, Principles of setting MEY target reference points for secondary species in the SESSF, draft report prepared for AFMA and SEMAC.

Ward, RD, Appleyard, SA, Daley, RK & Reilly, A 2001, ‘Population structure of pink ling (Genypterus blacodes) from south-eastern Australian waters, inferred from allozyme and microsatellite analyses', Marine and Freshwater Research, vol. 52, pp. 965–73.

Wayte, SE 2006, Eastern zone orange roughy: 2006 assessment, CSIRO, Hobart.

—— & Bax, N 2007, Stock assessment of the Cascade Plateau orange roughy 2006, CSIRO, Hobart.

—— 2012, ‘Jackass morwong (Nemadactylus macropterus) stock assessment based on data up to 2010', in GN Tuck (ed.), Stock assessmentfor the Southern and Eastern Scalefish and Shark Fishery 2011, part 1, AFMA & CSIRO Marine and Atmospheric Research, Hobart.

—— 2013, ‘Management implications of including a climate-induced recruitment shift in the stock assessment for jackass morwong (Nemadactylus macropterus) in south-eastern Australia', Fisheries Research, vol. 142, pp. 47–55.

—— 2014, ‘Jackass morwong (Nemadactylus macropus) 2014 RBC calculation', in GN Tuck (ed.), Stock assessment for the Southern and Eastern Scalefish and Shark Fishery 2013, part 1, AFMA & CSIRO Marine and Atmospheric Research, Hobart.

West, L, Stark, K, Murphy, J, Lyle, J & Ochwada-Doyle, F 2015, Survey of Recreational Fishing in New South Wales and the ACT, 2013/14, Fisheries Final Report Series 149, NSW Department of Primary Industries, Woollongong.

Williams, A, Althaus, F, Smith, ADM, Daley, R, Barker, BA & Fuller, M 2013, Developing and applying a spatially-based seascape analysis (the ‘habitat proxy' method) to inform management of gulper sharks: compendium of discussion papers, report to AFMA, CSIRO.

——, Hamer, P, Haddon, M, Robertson, S, Althaus, F, Green, M & Kool, J 2017, Determining blue-eye trevalla stock structure and improving methods for stock assessment, FRDC project 2013/015, FRDC, Canberra.

Wilson, DT, Patterson, HM, Summerson, R & Hobsbawn, PI 2009, Information to support management options for upper-slope gulper sharks (including Harrisson's dogfish and southern dogfish), final report to FRDC, project 2008/65, Bureau of Rural Sciences, Canberra.

Footnotes

1The orange roughy southern zone TAC contains both ‘incidental' catch allowance and ‘target' quota because quota is apportioned as a result of the orange roughy eastern zone stock assessment. Orange roughy from Pedra Branca in the southern zone is included as part of the assessed eastern stock. The incidental catch component was 31 t in 2016–17.

Chapter 10: East Coast Deepwater Trawl Sector

L Georgeson and D Mobsby

FIGURE 10.1 Area of the East Coast Deepwater Trawl Sector
TABLE 10.1 Status of the East Coast Deepwater Trawl Sector
Status Biological status2015 Fishing
mortality
2015 Biomass2016 Fishing
mortality
2016 BiomassComments
Alfonsino
(Beryx splendens)
Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedZero catch and effort in 2016–17.

Economic status
Before 2014–15, high levels of latency indicated low NER. No fishing activity in 2014–15 and 2015–16 indicates that NER were zero in those years.

Notes: NER Net economic returns.

[expand all]

10.1 Description of the fishery

Area fished

The East Coast Deepwater Trawl Sector (ECDTS) began as an exploratory fishery in the early 1990s, primarily taking orange roughy (Hoplostethus atlanticus) near Lord Howe Rise (Figure 10.1). The northern part of the fishery became part of the Coral Sea Fishery in 1994, and the southern part was amalgamated with the Southern and Eastern Scalefish and Shark Fishery (SESSF) in 2000.

Fishing methods

The ECDTS is a demersal and midwater trawl, and bottom-line (longline and dropline) fishery. Fishing in the 1990s mostly targeted orange roughy around Lord Howe Rise. Since 2000, the fishery has targeted mostly alfonsino (Beryx splendens). Important byproduct species include blue-eye trevalla (Hyperoglyphe antarctica) and boarfish (Pentacerotidae). Boarfish has a catch limit of 200 t to regulate catch, and orange roughy has a 50 t incidental catch limit. If catches exceed these limits, the fishery would be closed for the remainder of the season.

Management methods

The fishery operates in accordance with the SESSF harvest strategy framework (AFMA 2009; see Chapter 8). Fishers must have statutory fishing rights for the Commonwealth Trawl Sector (CTS) to be granted access to the ECDTS. When the SESSF was established, the Australian Fisheries Management Authority (AFMA) established permanent trawl exclusion areas to protect the eastern Australian seamounts, and areas around Lord Howe Island and Ball's Pyramid (Figure 10.1).

The ECDTS area is adjacent to Australia's extended continental-shelf jurisdiction (recognised in 2008 under the United Nations Convention on the Law of the Sea). New Zealand and Australian vessels fish in adjacent high-seas waters of the South Pacific Regional Fisheries Management Organisation (SPRFMO) Convention area. The distributions of most deepwater species taken by this sector extend well beyond the Exclusive Economic Zone (EEZ) areas fished by the sector, extending into the high seas, and across Lord Howe Rise and Challenger Plateau to the New Zealand EEZ.

Fishing effort

Effort in the ECDTS has been variable but generally low since the 1990s; in recent years, it has been low and sporadic. There has been no effort in the fishery since 2013–14.

TABLE 10.2 Main features and statistics for the ECDTS
Fishery statistics a 2015–16 fishing season2015–16 fishing season2015–16 fishing season2016–17 fishing season2016–17 fishing season
Stock TAC
(t)
Catch
(t)
Real value
(2015–16)
TAC
(t)
Catch
(t)
Alfonsino1,016001,0170
Total fishery 1,266 b 0 0 1,267 b 0

Fishery-level statistics 2015–16 fishing season2016–17 fishing season
Effort00
Fishing permits1010
Active vessels00
Observer coverage00
Fishing methodsDemersal and midwater trawlDemersal and midwater trawl
Primary landing portsBrisbane (Qld), Sydney (NSW)Brisbane (Qld), Sydney (NSW)
Management methodsInput controls: limited entry, boat SFRs
Output controls: TAC and ITQ (alfonsino); catch or trigger limits (orange roughy, blue-eye trevalla and boarfish)
Input controls: limited entry, boat SFRs
Output controls: TAC and ITQ (alfonsino); catch or trigger limits (orange roughy, blue-eye trevalla and boarfish)
Primary marketsDomestic: frozen or chilledDomestic: frozen or chilled
Management plan Southern and Eastern Scalefish and Shark Fishery Management Plan 2003 Southern and Eastern Scalefish and Shark Fishery Management Plan 2003

a Fishery statistics are provided by fishing season, unless otherwise indicated. Fishing season is 1 May to 30 April. Real-value statistics are by financial year and were not available for the 2016–17 financial year at the time of publication. b Includes a 200 t non-tradeable catch limit for boarfish and a 50 t incidental catch limit for orange roughy.
Notes: ITQ Individual transferable quota. SFR Statutory fishing right. TAC Total allowable catch.

10.2 Biological status

Alfonsino (Beryx splendens)

Alfonsino (Beryx splendens) 

Line drawing: William Murray

Stock structure

Alfonsino is a widely occurring pelagic species that aggregates around seamounts and features on the upper continental slope. Alfonsino in Australia's EEZ is currently managed as a single management unit across the CTS and the ECDTS, with a single total allowable catch (TAC) that applies only within the EEZ. Alfonsino is caught along the continental shelf break in the SESSF and the East Coast Deep Water Zone (ECDWZ). The alfonsino catch in the ECDWZ has largely been taken in an area south-east of Lord Howe Island—approximately half of this area is outside the Australian Fishing Zone (AFZ), effectively straddling both the ECDWZ and the high seas (Morison et al. 2013). The biological stock structure of alfonsino fished in the ECDTS is unknown. It is likely that alfonsino on the northern Lord Howe Rise constitutes a straddling stock, extending from within the Australian EEZ out into the high seas.

The first meeting of the SPRFMO Scientific Committee in 2013 recommended that the existence and distribution boundaries of alfonsino and orange roughy stocks that straddle EEZ boundaries should be identified (SPRFMO 2013). An assessment of orange roughy in the SPRFMO Convention area was published in 2014 (Tingley 2014), but no assessment of alfonsino has been undertaken.

Catch history

Fishing in the area of the ECDTS has been intermittent, and data are limited. In particular, catch and catch-per-unit-effort data are sporadic, fluctuating without any clear trend. Catches of alfonsino, the main target species, have been low in most years, usually below 100 t. Catches peaked at just over 400 t in 2004–05, and reached 200 t in 2000–01, 2005–06 and 2011–12 (Figure 10.2).

The landed alfonsino catch from the ECDTS decreased from 15 t in 2013–14 to zero in 2014–15, 2015–16 and 2016–17, reflecting zero fishing effort. The 2016–17 alfonsino TAC was 1,017 t.

FIGURE 10.2 Catch and TAC for alfonsino in the ECDTS and the CTS, 1999–2000 to 2016–17
Notes: CTS Commonwealth Trawl Sector. TAC Total allowable catch.
Stock assessment

The limited, patchy and highly variable nature of catch-and-effort data for alfonsino in the ECDTS resulted in the Slope Resource Assessment Group (SlopeRAG) rejecting early attempts at a tier 4 assessment in 2007 and recommending that alfonsino be assessed under tier 3.

The 2011 assessment (Klaer 2012) used age-frequency data from length frequencies and otoliths collected in 2007 and 2009. Catch-curve analyses estimated a lower total mortality than previous assessments and indicated that fishing mortality was less than F48 (the fishing mortality that would be expected to result in a spawning stock biomass of 48 per cent of the unfished level, on average, in the long term). Application of the SESSF tier 3 harvest control rules resulted in a recommended biological catch (RBC) of 1,160 t. However, application of the 50 per cent change-limiting rule (see Chapter 8) resulted in the TAC being set at 750 t for the 2011–12 season. The TAC was kept at 750 t for 2012–13, because no new data were available and little fishing was occurring in the ECDTS. The 2012 tier 3 assessment estimated an RBC of 1,196 t, which resulted in a TAC of 1,125 t for the 2013–14 fishing season after the 50 per cent change-limiting rule was applied (AFMA 2013).

The tier 3 assessment was updated in 2013, using catch-at-age data up to 2010 and New Zealand data from the high-seas fishery on the northern Lord Howe Rise. This assessment produced a total alfonsino RBC, including the high seas, of 1,228 t. The AFZ RBC, which was calculated as the total RBC minus the expected future high-seas catch based on average catch for the past four years, was 1,070 t. After applying the 5 per cent tier 3 discount factor, AFMA implemented a three-year TAC of 1,017 t for 2014–15 through to 2016–17, with 10 per cent overcatch and undercatch provisions.

The 2013 assessment update estimated current fishing mortality as FCURR = 0.022, well below the estimated FRBC = 0.149 (Klaer 2013). Fishing mortality has been negligible because catches have remained well below the TAC each year, and have been zero since 2013–14.

Stock status determination

The tier 3 assessment for alfonsino indicates that, since 2000, fishing mortality has remained below the level that would constitute overfishing. The most recent assessment indicates that fishing mortality is well below the target. As a result, this stock is classified as not subject to overfishing. Alfonsino catches have remained well below RBC levels, and no fishing effort or catch has occurred in the fishery since 2013–14. In the absence of any evidence to suggest otherwise, the stock is classified as not overfished.

10.3 Economic status

Key economic trends

Estimates of net economic returns (NER) are not available for the ECDTS, and estimates of the sector's gross value of production have been confidential. Fishing effort in the ECDTS declined by 85 per cent in 2013–14 to 8 hours. There was no fishing activity in 2014–15 and 2015–16.

The long distance to fishing grounds and use of trawl gear mean that fuel costs make up a high proportion of total fishing costs in the ECDTS. The average price for off-road diesel (which excludes goods and services tax) was 38 per cent lower in 2015–16 than in 2013–14. Indicative prices for alfonsino, the major targeted species in the ECDTS, increased in 2014–15 and 2015–16. Given that recent stock assessments have resulted in substantially increased RBCs, the low catches in recent years are not the result of low abundance. Inactivity in the ECDTS in 2014–15 and 2015–16 is likely to be the result of factors other than fuel costs, alfonsino price and alfonsino abundance. Higher expected profit in the CTS and other fisheries that permit holders operate in may be a key driver of inactivity in the ECDTS.

Management arrangements

The alfonsino TAC was 1,016 t in 2015–16 and 1,017 t in 2016–17. Given that recent stock assessments have resulted in substantially increased RBCs, the low catches in recent years are not the result of low abundance.

Performance against economic objective

The high level of latency, in terms of the proportion of the TAC caught, suggests that expected profit in the sector is insufficient to justify fishing effort. No fishing activity in 2014–15 and 2015–16 indicates that NER were zero in those years.

The sector's key target species, alfonsino, is currently managed under the SESSF harvest strategy as a tier 3 species, with a proxy fishing mortality target of F48. This approach to setting TACs for the species is consistent with meeting the economic objective of the Commonwealth Fisheries Harvest Strategy Policy (DAFF 2007).

10.4 Environmental status

The ECDTS has not been assessed separately under AFMA's ecological risk assessment process, but was included in the assessment of the CTS (Chapter 8). Orange roughy was declared conservation dependent in 2006. The Orange Roughy Conservation Programme (AFMA 2006) was replaced by the Orange Roughy Rebuilding Strategy in 2015 (AFMA 2014). There is no targeted fishing for this species in the ECDTS, and there has been no reported catch in the fishery since 2003.

AFMA publishes quarterly reports of logbook interactions with species protected under the Environment Protection and Biodiversity Conservation Act 1999 on its website. No interactions with species protected under the Act were reported in the ECDTS for 2016. Interactions with protected species and impacts on benthic habitats are unlikely to be of concern because of the low effort in the fishery in recent years.

10.5 References

AFMA 2006, Orange Roughy Conservation Programme, Australian Fisheries Management Authority, Canberra.

—— 2009, Harvest strategy framework for the Southern and Eastern Scalefish and Shark Fishery, version 1.2, AFMA, Canberra.

—— 2013, Determination of total allowable catches for SESSF for the 2013–14 season, AFMA, Canberra.

—— 2014, Orange Roughy Rebuilding Strategy 2014, AFMA, Canberra.

DAFF 2007, Commonwealth Fisheries Harvest Strategy: policy and guidelines, Australian Government Department of Agriculture, Fisheries and Forestry, Canberra.

Klaer, N 2012, ‘Yield, total mortality values and tier 3 estimates for selected shelf and slope species in the SESSF 2011', in GN Tuck (ed.), Stock assessment for the Southern and Eastern Scalefish and Shark Fishery 2011, part 2, AFMA & CSIRO Marine and Atmospheric Research, Hobart.

—— 2013, ‘Yield, total mortality values and tier 3 estimates for selected shelf and slope species in the SESSF 2012', in GN Tuck (ed.), Stock assessment for the Southern and Eastern Scalefish and Shark Fishery 2012, part 2, AFMA & CSIRO Marine and Atmospheric Research, Hobart.

Morison, AK, Knuckey, IA, Simpfendorfer, CA & Buckworth, RC 2013, South East Scalefish and Shark Fishery: draft 2012 stock assessment summaries for species assessed by GABRAG, ShelfRAG & Slope/DeepRAG, report for AFMA, Canberra.

SPRFMO 2013, Report of the 1st Scientific Committee meeting, La Jolla, United States, 21–27 October 2013, South Pacific Regional Fisheries Management Organisation, Wellington.

Tingley, G 2014, The estimation of initial biomass (B0) and catch limits for orange roughy in the SPRFMO area, Ministry for Primary Industries, New Zealand.

Chapter 11: Great Australian Bight Trawl Sector

A Moore and A Koduah

FIGURE 11.1 Relative fishing intensity in the Great Australian Bight Trawl Sector, 2016–17 fishing season
TABLE 11.1 Status of the Great Australian Bight Trawl Sector
Status Biological status2015 Fishing
mortality
2015 Biomass2016 Fishing
mortality
2016 Biomass Comments
Bight redfish
(Centroberyx gerrardi)
Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedCatch is below RBC. Estimate of current biomass is above the target.
Deepwater flathead
(Platycephalus conatus)
Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedCatch is below RBC. Estimate of current biomass is near the target.
Ocean jacket
(Nelusetta ayraud)
Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedCatch has been stable in recent years. No formal assessment. Fishery-independent survey data indicate stock is not overfished.
Orange roughy
(Hoplostethus atlanticus)
Not subject to overfishingUncertainNot subject to overfishingUncertainNo commercial catch. No formal assessment of biomass, and impact of historical catches is uncertain.

Economic status
NER are likely to have increased slightly in 2015–16. The positive effects of lower effort and the ongoing fall in the price of fuel are likely to have more than offset the negative effect on NER of a lower gross value of production.
Notes: NER Net economic returns. RBC Recommended biological catch.

Trawl catch
SETFIA

[expand all]

11.1 Description of the fishery

Area fished

The former Great Australian Bight Trawl Fishery was amalgamated with the Southern and Eastern Scalefish and Shark Fishery (SESSF) in 2003 to become the Great Australian Bight Trawl Sector (GABTS; Figure 11.1) of the SESSF.

The GABTS can be divided into a continental-shelf fishery (at depths of less than 200 m), an upper continental-slope fishery (at depths of about 200–700 m) and a deepwater fishery (on the mid- to lower slope, depth 700–1,000 m).

Fishing methods and key species

The fishing methods used in the GABTS are otter trawl and Danish-seine; pair trawling has been trialled in the past. In shelf waters, trawling is usually at depths of 120–200 m, targeting mainly deepwater flathead (Platycephalus conatus) and bight redfish (Centroberyx gerrardi). The shelf fishery operates year round. For upper continental-slope trawling, target species include blue grenadier (Macruronus novaezelandiae), western gemfish (Rexea solandri) and pink ling (Genypterus blacodes). Ocean jacket (Nelusetta ayraud) is an important byproduct species, with 228 t landed in 2016–17. Other byproduct species include angel shark (Squatina spp.), yellow-spotted boarfish (Paristiopterus gallipavo), latchet (Pterygotrigla polyommata) and jackass morwong (Nemadactylus macropterus). Danish-seine targets deepwater flathead on the continental shelf.

Management methods

The Commonwealth Fisheries Harvest Strategy Policy (HSP; DAFF 2007) and the SESSF Harvest Strategy Framework (AFMA 2009) both apply to the key species in the GABTS (see Chapter 8). Under the framework, recommended biological catches (RBCs) are usually based on achieving a default target reference point of 48 per cent of the unfished biomass (0.48B0), as a proxy for the biomass producing maximum economic yield (BMEY). However, a bio-economic model (Kompas et al. 2012) estimated BMEY target reference points of 0.43B0 for deepwater flathead and 0.41B0 for bight redfish in the GABTS. These estimated BMEY targets were used by the Australian Fisheries Management Authority (AFMA) Commission to set the total allowable catch (TAC) for bight redfish and deepwater flathead for the 2016–17 fishing season.

Fishing effort

Total trawl fishing effort across all depths in 2016–17 was 12,480 trawl hours, down from the 2004–05 peak of 30,866 trawl hours. The continental shelf continues to be the focus of fishing effort, with 11,888 trawl hours in 2016–17 (Figure 11.2), compared with 591 trawl hours on the continental slope (Figure 11.3).

The deepwater fishery historically targeted orange roughy (Hoplostethus atlanticus). However, since 2007, when most of the historical orange roughy fishing grounds were closed under the Orange Roughy Conservation Programme (AFMA 2006), little effort has occurred at these depths.

The fishery has 10 boat statutory fishing rights that allow a boat to fish in the fishery, and separate quota statutory fishing rights that allow quota species to be landed. Four trawl vessels and one Danish-seine vessel operated in the fishery in 2016–17.

Catch

Reduced effort in the fishery has led to reduced catches of key target species over time. Deepwater flathead continues to dominate catches, with 636 t landed in the 2016–17 fishing season, which was 55 per cent of the TAC. Bight redfish landings in 2016–17 were 274 t, which was 23 per cent of the TAC.

FIGURE 11.2 Catch and effort on the GABTS shelf, 1988–89 to 2016–17

FIGURE 11.3 Catch and effort on the GABTS slope, 1988–89 to 2016–17
TABLE 11.2 Main features and statistics for the GABTS
Fishery statistics a 2015–16 fishing season2015–16 fishing season2015–16 fishing season2016–17 fishing season2016–17 fishing season2016–17 fishing season
Stock TAC
(t)
Catch
(t)
Real value
(2015–16)
TAC
(t)
Catch
(t)
Real value
(2016–17)
Bight redfish2,358191$940,0001,179274na
Deepwater flathead1,150631$4.38 million1,150636na
Ocean jacket216$366,000228na
Orange roughy b0
(200, 50)
0
(0, 0)
00
(200, 50)
0
(0, 0)
na
Total 3,508 (250) c 1,038 $7.69 million 2,329 (250)c 1,138 na

Fishery-level statistics 2015–16 fishing season2016–17 fishing season
Effort13,509 trawl hours; 511 seine shots12,480 trawl hours; 442 seine shots
Fishing permits1010
Active vessels3 trawl; 1 seine4 trawl; 1 seine
Observer coverage182 trawl hours (1.35%)366 trawl hours (2.93%)
Fishing methodsTrawl, Danish-seineTrawl, Danish-seine
Primary landing portsAdelaide, Port Lincoln, Thevenard (South Australia) Adelaide, Port Lincoln, Thevenard (South Australia)
Management methodsInput controls: limited entry, area closures, gear restrictions
Output controls: ITQs, TACs, trigger limits
Input controls: limited entry, area closures, gear restrictions
Output controls: ITQs, TACs, trigger limits
Primary marketsDomestic: Melbourne, Perth, SydneyDomestic: Melbourne, Perth, Sydney
Management plan Southern and Eastern Scalefish and Shark Fishery Management Plan 2003 Southern and Eastern Scalefish and Shark Fishery Management Plan 2003

a Fishery statistics are provided by fishing season, unless otherwise indicated. Fishing season is 1 May to 30 April. Real-value statistics are by financial year and were not available for the 2016–17 financial year at time of publication. b A 200 t research quota and a 50 t bycatch TAC in the Albany and Esperance zones are not included in the total catch. c Research allowance.
Notes: ITQ Individual transferable quota. na Not available. SFR Statutory fishing rights. TAC Total allowable catch. – Not applicable.

Bight redfish
AFMA

11.2 Biological status

Bight redfish (Centroberyx gerrardi)

Bight redfish (Centroberyx gerrardi) 

Line drawing: FAO

Stock structure

The biological stock structure of bight redfish is unknown. It is considered to be a single biological stock in the GABTS for assessment and management purposes.

Catch history

Catch of bight redfish in the GABTS increased to 572 t in 2003–04, before almost doubling in association with the temporary introduction of a freezer trawler to the fishery. Catch reached a peak of 1,407 t in 2007–08. The freezer trawler departed in 2008, and effort decreased to around half of peak levels. Landed catch in the 2016–17 fishing season was 274 t (Figure 11.4).

FIGURE 11.4 Bight redfish annual catches and fishing season TACs in the GABTS, 1988 to 2016
Note: TAC Total allowable catch.
Stock assessment

The target reference point for bight redfish of 41 per cent of the unfished spawning stock biomass (0.41SB0; Kompas et al. 2012) was accepted by the Great Australian Bight Resource Assessment Group (GABRAG) in 2011 (AFMA 2011). The 2011 tier 1 stock assessment for bight redfish (Klaer 2011) was updated in 2015 (Haddon 2015). The base-case assessment predicted the female spawning biomass at the start of 2015–16 to be 63 per cent of unexploited female spawning stock biomass, above the target reference point of 0.41SB0. The unexploited female spawning biomass was estimated to be 5,451 t. The large reduction in the estimate of female spawning biomass from the 2011 assessment (26,210 t) reflects that the data now available for the updated assessment are more informative about the unfished biomass and the effects of fishing (Figure 11.5).

Fishery-independent trawl surveys were undertaken each year between 2006 and 2011 (except for 2010), and estimated relative abundance of the main target and byproduct species on the shelf (Knuckey & Hudson 2007; Knuckey et al. 2008, 2009, 2011). A 2015 fishery-independent trawl survey estimated that the relative biomass of bight redfish (2,573 t; coefficient of variation [CV] 0.28) had decreased 80 per cent from the previous 2011 estimate (13,189 t; CV 0.13). The GABTS industry has noted a decrease in available bight redfish in recent seasons. Length-frequency data suggest a truncation of larger bight redfish between 2011 and 2013. Ageing data also indicate a reduction in the abundance of older redfish in recent years.

The updated stock assessment (Haddon 2015) produced an RBC under the 20:35:41 harvest control rule of 862 t for the 2016–17 fishing season, or three- or five-year RBCs of 828 t and 797 t, respectively. Application of the large change–limiting rule limited the reduction in the 2016–17 fishing season TAC to 1,179 t.

FIGURE 11.5 Estimated spawning biomass of bight redfish in the GABTS, 1962 to 2014
Source: Haddon 2015
Stock status determination

The 2015 stock assessment predicted female spawning biomass to be 63 per cent of unfished levels and above the target reference point of 0.41B0. Catch in recent seasons continues to be well below RBCs. On this basis, bight redfish is classified as not overfished and not subject to overfishing.

Deepwater flathead (Platycephalus conatus)

Deepwater flathead (Platycephalus conatus) 

Line drawing: Karina Hansen

Stock structure

The biological stock structure of deepwater flathead is unknown. The stock is considered to be a single biological stock in the GABTS for assessment and management purposes.

Catch history

Catch of deepwater flathead peaked in 2003–04 at just under 2,500 t, and has been relatively stable at under 1,000 t since 2008–09. Landed catch in the 2016–17 fishing season was 636 t (Figure 11.6).

FIGURE 11.6 Deepwater flathead annual catch and fishing season TACs in the GABTS, 1988 to 2016
Note: TAC Total allowable catch.
Stock assessment

The target reference point for deepwater flathead of 43 per cent of the unfished spawning stock biomass (0.43SB0; Kompas et al. 2012) was accepted by GABRAG in 2011 (AFMA 2011). The 2013 tier 1 stock assessment for bight redfish (Klaer 2013) was updated in 2016 (Haddon 2016). The 2016 base-case assessment predicted the female spawning biomass at the start of 2016–17 to be 45 per cent of unexploited female spawning stock biomass, above the target reference point of 0.43B0. This depletion level is consistent with the 2013 assessment. The unexploited female spawning biomass was estimated to be 4,993 t. Application of the 20:35:43 harvest control rule produced an RBC for 2014–15 of 1,146 t. The multiyear TAC of 1,150 t was retained for the 2016–17 fishing season.

The results of the 2015 fishery-independent trawl survey (Knuckey et al. 2015) suggested that estimated relative biomass of deepwater flathead had decreased to 5,065 t (CV 0.09), compared with 9,227 t in the 2011 survey (CV 0.05)—this is a 45 per cent reduction (Knuckey et al. 2009, 2011, 2015). The updated stock assessment suggested no change in depletion level between 2013 and 2016, although the estimate of unexploited female spawning stock biomass had decreased from 9,320 t to 4,993 t. The GABTS industry has noted a decrease in available deepwater flathead in recent seasons, which correlates with decreasing catch. There is no evidence of a truncation in size or age structure of deepwater flathead (Haddon 2016).

FIGURE 11.7 Estimated spawning biomass of deepwater flathead in the GABTS, 1982 to 2015
Source: Haddon 2016
Stock status determination

The 2016 stock assessment predicted spawning biomass in 2016–17 to be near the target reference point and above the limit reference point from the HSP (0.2SB0). Catch continues to be below the RBC. On this basis, deepwater flathead is classified as not overfished and not subject to overfishing.

Ocean jacket (Nelusetta ayraud)

Ocean jacket (Nelusetta ayraud) 

Line drawing: FAO

Stock structure

The biological stock structure of ocean jacket is unknown. In the GABTS, it is assessed as a separate stock from the stock in the Commonwealth Trawl and Scalefish Hook sectors.

Catch history

Landed catch of ocean jacket peaked in 2005 at 527 t, but then decreased, and has been less than 250 t since 2008–09 (Figure 11.8). Landed catch in the 2016–17 fishing season was 228 t.

FIGURE 11.8 Ocean jacket catch in the GABTS, 1986 to 2016
Stock assessment

Formal stock assessments are not conducted for ocean jacket in the GABTS. Standardised catch rates have been variable; the most recent catch rates were similar to those at the start of the series (1986) (Sporcic & Haddon 2015; Figure 11.9).

Ocean jacket represented 16–35 per cent of survey catch by weight in the 2006, 2008, 2009 and 2011 fishery-independent trawl surveys, with an increase in relative abundance between 2009 and 2011 (Knuckey & Hudson 2007; Knuckey et al. 2008, 2009, 2011). Ocean jacket represented 7 per cent of the catch in the 2015 fishery-independent trawl survey, with an estimated relative biomass of 3,702 t (CV 0.19) (Knuckey et al. 2015) compared with 27,712 t (CV 0.20) in 2011. A bycatch survey of the GABTS in 2002 indicated that ocean jacket is often discarded (Knuckey & Brown 2002), potentially limiting the use of commercial catch-per-unit-effort as an index of abundance for this species.

Ocean jacket is a relatively short-lived species (approximately six years), reaching maturity within 2–3 years. Large cyclical changes in abundance appear to have occurred off eastern Australia (Miller & Stewart 2009). Historical catch data suggest that ocean jacket was fished down off the east coast of Australia in the 1920s and 1950s (Klaer 2001). There are no age data for ocean jacket from the GABTS, and the available historical length-frequency data are too old to be used as an index of abundance.

FIGURE 11.9 Standardised catch rate for ocean jacket in the GABTS, 1986 to 2013
Source: Sporcic & Haddon 2015
Stock status determination

No formal stock assessment for ocean jacket in the GABTS has been done. However, its catch histories and life history characteristics suggest that it is unlikely that the stock is overfished. The level of catch in 2016–17 is unlikely to constitute overfishing. On this basis, ocean jacket in the GABTS is classified as not overfished and not subject to overfishing.

Orange roughy (Hoplostethus altanticus)

Orange roughy (Hoplostethus altanticus) 

Line drawing: Rosalind Murray

Stock structure

The stock structure of orange roughy in the Australian Fishing Zone (AFZ) is unresolved. Based on the existing data and fishery dynamics, multiple regional stocks of orange roughy are assumed, and the fishery is managed and assessed as a number of discrete regional management units, shown in Figure 9.34 (Chapter 9).

Gonçalves da Silva et al. (2012) examined variation in a large number of loci using genetic techniques that have the power to detect low levels of genetic differentiation. The study concluded that orange roughy in the AFZ form a single genetic stock, but identified some differentiation between Albany/Esperance, Hamburger Hill (in the Great Australian Bight) and south-eastern Australia. It was noted that the amount of genetic exchange needed to maintain genetic homogeneity is much less than the amount needed for demographic homogeneity, and that residency or slow migration may result in separate demographic units, despite genetic similarity (Morison et al. 2013).

Catch history

Catch of orange roughy in the GABTS peaked at 3,757 t in 1988–89 and then declined (Figure 11.10). Since 1990, most of the GABTS catch has come from grounds off Albany and Esperance in the western part of the fishery. Early fishery-independent trawl surveys on the continental slope in the Great Australian Bight reported that orange roughy had the highest maximum catch rate (1,820 kg/hour) of any slope species at that time (Newton & Klaer 1991). The highest catch rates came from the locations of the original aggregations off Kangaroo Island and Port Lincoln, although the surveys found no large aggregations comparable with the historical aggregations. It seems likely that orange roughy across the Great Australian Bight has been depleted, with no large aggregation being seen since 1990. However, the actual level of depletion is unknown. Catch was zero between 2008–09 and 2011–12, and negligible thereafter. No catch was reported in the 2016–17 fishing season.

FIGURE 11.10 Orange roughy catch in the GABTS, 1987 to 2016
Stock assessment

No quantitative stock assessment has been conducted for orange roughy in the GABTS because the available data are sporadic and spatially scattered (Knuckey et al. 2010).

Early catches were reported as coming from temporary feeding aggregations associated with cold-water upwelling off Kangaroo Island and Port Lincoln. Catches from these aggregations ranged from 2,500 t to 3,784 t (Newton 1989). Aggregations have not been found in the same locations since then (Wayte 2004). A spawning aggregation was discovered in 1990 on a ridge 30 nautical miles from the Port Lincoln grounds (Newton & Tuner 1990). This aggregation, which has not been seen since, initially supported trawl catches of around 40 t/shot, typical of lightly exploited orange roughy fisheries, but only yielded a total catch of 800 t before being depleted.

Orange roughy was listed as conservation dependent under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) in 2006. A deepwater management strategy was implemented to address the requirements of the Orange Roughy Conservation Programme (AFMA 2006), under which commercial fishing was closed in several orange roughy zones across the Great Australian Bight, particularly the areas deeper than 700 m. More than 96 per cent of the historical catch (1988 to 2005) and more than 99 per cent of the more recent catch (2001 to 2005) was taken in these closed zones. Until sustainable harvest levels can be determined, fishing will be allowed in these zones only under a research program that has been approved by AFMA. The allocated research quota for 2015–16 was 200 t, but no catch was taken under a research permit during this season. The orange roughy incidental catch allowance remained at 50 t for the 2015–16 fishing season, with zero reported catch. The Orange Roughy Conservation Programme 2006 has been replaced by the Orange Roughy Rebuilding Strategy 2014 (AFMA 2014). Existing arrangements in the GABTS fishery have been maintained under the updated rebuilding strategy.

Stock status determination

There have been no recent surveys or representative catch-trend data to determine the abundance of orange roughy in the Great Australian Bight. As a result, this stock is classified as uncertain with regard to the level of biomass. Given that zero or negligible orange roughy catch has been reported in recent years, and that areas where more than 96 per cent of historical catches were taken are now closed, orange roughy is classified as not subject to overfishing.

11.3 Economic status

Key economic trends

Estimates of net economic returns (NER) for the GABTS are not available. The real gross value of production (GVP) for the fishery increased from $19.90 million in 2005–06 to a peak of $22.42 million in 2006–07 (in 2015–16 dollars; Figure 11.11). Reductions in the GABTS catch resulted in real GVP declining substantially in the next two years, falling to $10.50 million in 2008–09; GVP then increased in 2009–10 to $13.36 million. Following this, real GVP for the fishery remained steady at around $12.00 million until 2013–14. An average of around $8.00 million was generated over the following two years. GVP in 2015–16 was $7.69 million. In 2015–16, deepwater flathead contributed $4.38 million (57 per cent of total GVP), and bight redfish contributed $940,000 (12 per cent).

Recent declines in catch are consistent with reductions in effort, which would have reduced sector costs. Changes in hours trawled have been closely correlated with changes in GVP over the examined period (Figure 11.11). Hours trawled decreased from 30,399 hours in 2005–06 to 15,820 hours in 2014–15. Hours trawled declined by a further 15 per cent in 2015–16 to 13,509 hours. The decline in effort in 2015–16 coincided with a 23 per cent fall in the price of fuel. Although GVP declined for the second consecutive year (by 33 per cent compared with 2013–14), the decline in effort and unit fuel price suggests that costs in the fishery fell faster than revenue in 2015–16, suggesting an increase in profitability.

FIGURE 11.11 Real GVP for the GABTS by key species and trawl hours, 2005–06 to 2015–16
Notes: GVP Gross value of production. Trawl hours do not include Danish-seine effort. One Danish-seine vessel was active from 2012–13 to 2016–17.

Although lower catches have driven the decrease in GVP in recent years, this has been partially offset by increasing prices received for key species caught in the sector (Figure 11.12). Higher prices in 2009–10, which are considered to partially reflect improvements in product quality (GABMAC 2009, 2010), drove the increase in GVP between 2008–09 and 2010–11. Average prices in 2015–16 were $7.11 per kilogram for deepwater flathead and $5.31 per kilogram for bight redfish, up from $5.11 per kilogram for deepwater flathead and $3.16 per kilogram for bight redfish (2015–16 dollars) in 2005–06.

Trawling—the main method used in the sector—is typically fuel intensive. Fluctuations in the price of fuel are therefore likely to be a key driver of sector profitability. The Australian average off-road diesel price followed a decreasing trend over the period examined (Figure 11.12). It peaked in 2007–08 at $1.17 per litre, before declining to $0.82 per litre in 2009–10, and falling sharply in 2015–16 to $0.62 per litre (all expressed in 2015–16 dollars). A high price of fuel can negatively affect profitability, but increases in fish prices since 2003–04 and the significant fall in the price of fuel in 2014–15 have reduced this impact.

FIGURE 11.12 Annual average prices for deepwater flathead and bight redfish, and annual average off-road diesel price, 2005–06 to 2015–16
Note: The off-road diesel price is the price per litre paid by farmers (excludes goods and services tax).

Management arrangements

Like other SESSF sectors, the GABTS is a limited-entry fishery managed under TACs for target species, allocated as individual transferable quotas. During the 2016–17 fishing season, 636 t of deepwater flathead was caught (55 per cent of the 1,150 t TAC), and 274 t of bight redfish was caught (23 per cent of the 1,179 t TAC). Market prices for bight redfish are sensitive to supply (Kompas et al. 2012), so the high level of latency may be partly explained by fishers not wanting to land large volumes of bight redfish that could drive down the market price. For this reason, the industry has voluntary trip limits in place for bight redfish.

The GABTS began a trial of fishery co-management in July 2009 (AFMA 2012a). This has seen the Great Australian Bight Fishing Industry Association take a greater role in management decisions, including making direct operational recommendations to AFMA, improving fisheries data collection, developing a chain-of-custody process to improve product traceability and developing a boat operating procedures manual. Such an approach should be associated with improvements in the cost, efficiency and adaptability of management (FRDC 2008). The trial of co-management arrangements received positive feedback from those operating in the GABTS (GABMAC 2010), and these arrangements have been maintained in the fishery.

Performance against economic objective

The most recent stock assessments for bight redfish projected biomass levels at the start of 2014–15 to be above the target (Haddon 2015), potentially allowing increased profits from the species as it is fished down to its maximum economic yield (MEY) target reference point. Similarly, the latest assessment for deepwater flathead indicates that the stock is at, or slightly above, the MEY target (Haddon 2016). Hence, it is unlikely that fishery profitability is constrained by stock size.

Estimates of specific bio-economic target reference points for the two key species have improved the ability to manage stocks at levels that maximise NER. However,as noted by Kompas et al. (2012), the accuracy of the target for each species could potentially be improved with information on how prices for each species are influenced by catch levels. Taking these factors into account in the setting of target reference points for each species would allow an improved assessment of economic performance.

11.4 Environmental status

The GABTS ecological risk management report (AFMA 2008; updated 2012b, 2015) indicated that two byproduct invertebrate species groups—cuttlefish (various species) and octopods (various species)—were at high risk in this fishery (level 2 Residual Risk Assessment). However, this risk determination primarily reflected uncertainty resulting from a lack of data. The level 3 Sustainability Assessment for Fishing Effects (SAFE) excluded invertebrates and indicated that fishing mortality did not exceed the reference point for any of the 204 vertebrate species assessed (Zhou et al. 2007). Impacts on bycatch species have been further reduced by a decrease in effort and closures in the fishery.

As part of their boat-specific seabird management plans, vessels are required to use effective seabird mitigation devices. In late 2014, AFMA completed a trial, using observers, to test the effect of seabird mitigation devices on seabird interactions with otter trawlers. The trial showed that the use of warp deflectors (large floats attached in front of trawl warps to scare birds away—often called ‘pinkies') reduced heavy contact between actively feeding seabirds and warp wires by around 75 per cent (Pierre et al. 2014). Based on the outcomes of the trial, AFMA mandated a minimum requirement in seabird management plans of 600 mm pinkies. The South East Trawl Fishing Industry Association (SETFIA) has also introduced a code of conduct and a training program to improve seabird avoidance measures, and trialled alternative seabird mitigation devices, including water sprayers and bird bafflers. The trial was completed in June 2016, but the report is not yet publicly available. SETFIA has reported that water sprayers and bird bafflers used in the trial reduced interactions between seabirds and the warp by 90 per cent and 96 per cent, respectively. Following the success of this trial, AFMA announced that from 1 May 2017 all vessels in the Commonwealth Trawl Sector and GABTS fisheries must use one of the following mitigation devices: sprayers, bird bafflers or pinkies with zero discharge of fish waste.

AFMA publishes quarterly reports of logbook interactions with protected species on its website. Two interactions with species protected under the EPBC Act were reported in the GABTS in 2016. One interaction was reported with a seahorse or pipefish, which was reported to be dead.

11.5 References

AFMA 2006, Orange Roughy Conservation Programme, Australian Fisheries Management Authority, Canberra.

—— 2008, Residual Risk Assessment of the level2 ecological risk assessment species results: report for the Great Australian Bight trawl sub-fishery of the Southern and Eastern Scalefish and Shark Fishery, AFMA, Canberra.

—— 2009, Harvest strategy framework for the Southern and Eastern Scalefish and Shark Fishery, version 1.2, September 2009, AFMA, Canberra.

—— 2011, ‘Southern and Eastern Scalefish and Shark Fishery—Great Australian Bight Resource Assessment Group (GABRAG) meeting, 27–28 October 2011', AFMA, Adelaide.

—— 2012a, Great Australian Bight Trawl Fishery co-management trial, AFMA, Canberra.

—— 2012b, Residual risk assessment of the level 2 Productivity Susceptibility Analysis: report for the otter board trawl method of the Great Australian Bight Trawl Sector, AFMA, Canberra.

—— 2014, Orange roughy (Hoplostethus atlanticus) stock rebuilding strategy 2014, AFMA, Canberra.

—— 2015, Ecological risk management strategy for the Southern and Eastern Scalefish and Shark Fishery, AFMA, Canberra

DAFF 2007, Commonwealth Fisheries Harvest Strategy: policy and guidelines, Australian Government Department of Agriculture, Fisheries and Forestry, Canberra.

FRDC 2008, Co-management: managing Australia's fisheries through partnership and delegation, report of the FRDC's national working group on the fisheries co-management initiative, project 2006/068, Fisheries Research and Development Corporation, Canberra.

GABMAC 2009, ‘Southern and Eastern Scalefish and Shark Fishery—Great Australian Bight Management Advisory Committee (GABMAC) meeting, 28 May 2009, Canberra', final minutes, AFMA, Canberra.

—— 2010, ‘Southern and Eastern Scalefish and Shark Fishery—Great Australian Bight Management Advisory Committee (GABMAC) meeting', AFMA, Canberra.

Gonçalves da Silva, A, Appleyard, S & Upston J 2012, Orange roughy (Hoplostethus atlanticus)population genetic structure in Tasmania, Australia: testing assumptions about eastern zone orange roughy stock structure, CSIRO Marine and Atmospheric Research, Hobart.

Haddon, M 2015, Bight redfish(Centroberyx gerrardi) stock assessment using data to 2014/2015, draft report, CSIRO Oceans and Atmosphere, Hobart.

—— 2016, Deepwater flathead (Platycephalus conatus) stock assessment using data to 2015/16, draft report, CSIRO Oceans and Atmosphere, Hobart.

Klaer, N 2001, ‘Steam trawl catches from southeastern Australia from 1918 to 1957: trends in catch rates and species composition', Marine and Freshwater Research, vol. 52, pp. 399–410.

—— 2011, ‘Bight redfish (Centroberyx gerrardi) stock assessment based on data up to 2010/11', in GN Tuck (ed.), Stock assessment for the Southern and Eastern Scalefish and Shark Fishery 2012, part 1, AFMA & CSIRO Marine and Atmospheric Research, Hobart.

—— 2013, ‘Deepwater flathead (Neoplatycephalus conatus) stock assessment based on data up to 2012/13', in GN Tuck (ed.), Stock assessment for the Southern and Eastern Scalefish and Shark Fishery 2013, part 1, AFMA & CSIRO Marine and Atmospheric Research, Hobart.

Knuckey, IA & Brown, LP 2002, Assessment of bycatch in the Great Australian Bight Trawl Fishery, final report to FRDC, report 2000/169, FRDC, Canberra.

—— & Hudson, R 2007, Resource survey of the Great Australian Bight Trawl Fishery 2006, report to AFMA, Canberra.

——, Hudson, R & Koopman, M 2008, Resource survey of the Great Australian Bight Trawl Fishery 2008, report to AFMA, Canberra.

——, Koopman, M & Hudson, R 2009, Resource survey of the Great Australian Bight Trawl Fishery 2009, report to AFMA, Canberra.

——, Hudson, R & Nemec, J 2010, Monitoring orange roughy in the Great Australian Bight 2010, report to AFMA, Canberra.

——, Koopman, M & Hudson, R 2011, Resource survey of the Great Australian Bight Trawl Sector 2011, report to AFMA, Canberra.

——, Koopman, M & Hudson, R 2015, Resource survey of the Great Australian BightTrawl Sector 2015, report to AFMA, Canberra.

Kompas, T, Che, N, Chu, L & Klaer, N 2012, Transition to MEY goals for the Great Australian Bight Trawl Fishery, report to FRDC, Australian Centre for Biosecurity and Environmental Economics, Crawford School of Public Policy, Australian National University, Canberra.

Miller, M & Stewart, J 2009, ‘The commercial fishery for ocean leatherjackets (Nelusetta ayraudi, Monacanthidae) in New South Wales, Australia', Asian Fisheries Science, vol. 22, no. 1, pp. 257–64.

Morison, AK, Knuckey, IA, Simpfendorfer, CA & Buckworth, RC 2013, South East Scalefish and Shark Fishery: draft 2012 stock assessment summaries for species assessed by GABRAG, ShelfRAG & Slope/DeepRAG, report to AFMA, Canberra.

Newton, G 1989, ‘The orange roughy fishery of the Great Australian Bight', Australian Society for Fish Biology conference, 1989.

—— & Tuner, D 1990, ‘Spawning roughy in the GAB—a new find', Australian Fisheries, October, 1990.

—— & Klaer, N 1991, ‘Deep-sea demersal fisheries of the Great Australian Bight: a multivessel trawl survey', Bureau of Rural Resources Bulletin, no. 10, Australian Government Publishing Service, Canberra.

Pierre, J, Gerner, M & Penrose, L 2014, Asessing the effectiveness of seabird mitigation devices in the trawl sectors of the Southern and Eastern Scalefish and Shark Fishery in Australia, AFMA, Canberra.

Sporcic, M & Haddon, M 2015, Catch rate standardizations for selected SESSF species (data to 2013), CSIRO Oceans and Atmosphere Flagship, Hobart.

Wayte, S 2004, Analysis of orange roughy catch data from the Great Australian Bight, report to AFMA, Canberra.

Zhou, S, Smith, T & Fuller, M 2007, Rapid quantitative risk assessment for fish species in major Commonwealth fisheries, report to AFMA, Canberra.

Chapter 12: Shark Gillnet and Shark Hook sectors

N Marton and A Koduah

FIGURES 12.1 Relative fishing intensity in (a) the Shark Gillnet Sector and (b) the Shark Hook Sector of the Southern and Eastern Scalefish and Shark Fishery, 2016–17 fishing season

(a) the Shark Gillnet Sector

(b) the Shark Hook Sector

 

Gillnet vessel
AFMA
TABLE 12.1: Status of the Shark Gillnet and Shark Hook sectors
Status
Biological status
2015
Fishing mortality
2015
Biomass
2016
Fishing mortality
2016
Biomass
Comments
Elephantfish
(Callorhinchus milii)
Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedCPUE is above target; catch is below RBC.
Gummy shark
(Mustelus antarcticus)
Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedCatch is below RBC. Estimates of pup production are close to or above the target.
Sawshark
(Pristiophorus cirratus, P. nudipinnis)
Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedCPUE is above target; catch is below RBC.
School shark
(Galeorhinus galeus)
UncertainOverfished UncertainOverfished Uncertain if total mortality will allow recovery in required time frame. Estimate of pup production is below 20% of unexploited levels.

Economic status a
NER were –$2.9 million in 2012–13. Preliminary estimates for 2013–14 indicate that NER are likely to remain negative. Although gummy shark biomass is not constraining NER, the management of non-target species and marine mammal interactions has likely contributed to a fall in NER in recent years.

a NER refer to the entire Gillnet, Hook and Trap Sector; therefore, this figure includes scalefish. Shark species account for around 70 per cent of total Gillnet, Hook and Trap Sector gross value of production.
Notes: CPUE Catch-per-unit-effort. NER Net economic returns. RBC Recommended biological catch.

[expand all]

12.1 Description of the fishery

Area fished

The Shark Gillnet and Shark Hook sectors (SGSHS) extend south from the New South Wales – Victoria border, around Tasmania, and west to the South Australia – Western Australia border. Most fishing occurs in waters adjacent to the coastline and throughout Bass Strait (Figure 12.1).

Fishing methods and key species

The SGSHS uses demersal gillnet and longline to target gummy shark (Mustelus antarcticus). School shark (Galeorhinus galeus), elephantfish (Callorhinchus milii) and sawsharks (Pristiophorus cirratus and P. nudipinnis) are byproducts from the gummy shark fishery. School shark was historically the primary target species in the fishery, but biomass was reduced below the limit reference point around 1990. It remains an important byproduct species and is the second most economically important species in the fishery.

Other important byproduct species (by weight) are snapper (Pagrus auratus), whiskery shark (Furgaleus macki), broadnose sevengill shark (Notorynchus cepedianus), bronze whaler (Carcharhinus brachyurus), draughtboard shark (Cephaloscyllium laticeps) and blue morwong (Nemadactylus valenciennesi).

Management methods

The fishery is managed using a combination of input controls (gear restrictions and closed areas) and output controls (individual transferable quotas and limits on the proportion of school shark to gummy shark catch). The four key commercial stocks taken in the SGSHS are managed under the Southern and Eastern Scalefish and Shark Fishery (SESSF) harvest strategy framework (AFMA 2009). The harvest strategy is summarised in Chapter 8. School shark is subject to incidental catch limits, and other measures to reduce targeting and catch for a number of seasons. Additional current measures include closure of waters deeper than 183 m to gillnet fishing, closure of waters shallower than 183 m to auto-longline fishing (except in South Australia for shark), and various spatial closures to protect pupping areas.

A number of gear and area closures (primarily off South Australia) have been introduced in the SGSHS to reduce the risk of interactions with Australian sea lions and dolphins. These have changed the fishing areas and targeting behaviour of fishers, influenced the take of target species and consequently affected catch-per-unit-effort (CPUE). These and other key wildlife bycatch issues are discussed further in Chapter 8.

In response to the gillnet spatial closures, a recent project looked at increasing the use of demersal longlines instead of using gillnets to target gummy shark (Knuckey et al. 2014). However, this is still an experimental fishery, with temporary hook permits being made available for holders of gillnet statutory fishing rights operating in South Australian waters (AFMA 2015a).

From 1 July 2015, electronic monitoring (e-monitoring) has been mandatory for all full-time vessels in the SGSHS. Video footage of at least 10 per cent of all recorded hauls is reviewed to verify the accuracy of logbooks. In addition, gillnet boats operating off South Australia's Australian Sea Lion Zones are subject to 100 per cent review of video footage for interactions with protected species. Logbooks must be completed for 100 per cent of shots.

Fishing effort

Before spatial closures, which have been progressively implemented since 2003, effort in the SGSHS was spread across the waters of South Australia and eastern Victoria. However, the spatial closures discussed above have resulted in gillnet effort being concentrated off Victoria (Figure 12.1). Effort in the gillnet sector peaked in 1987 at 99,000 km of gillnet hauled, but has decreased to around one-third of this level in recent years.

Catch history

Fishing for sharks in the waters off southern Australia began in the 1920s, using longlines. During the 1970s and 1980s, the sector mainly targeted school shark (Figure 12.2). Adoption of monofilament gillnets and concern about mercury content in large school sharks, coupled with declining school shark catches, resulted in gummy shark becoming the principal target species from around 1986 (Figures 12.2 and 12.3). This transition occurred in the early 1970s in Bass Strait, and later in the waters off South Australia and Tasmania. Recent catch records indicate that trawl operations in the SESSF are now landing as much sawshark as gillnet operations. Most of the landed catch of elephantfish is taken using gillnets in eastern Bass Strait.

FIGURE 12.2 Annual landings and effort in the SGSHS, by species, 1970 to 2016
Note: ‘Equivalent gillnet effort' is an estimate of total effort after converting hook effort to the equivalent gillnet effort using the methods in Walker et al. (1994).
FIGURE 12.3 Annual landings in the CTS, by species, 2001 to 2016
TABLE 12.2 Main features and statistics for the SGSHS a
Fishery statistics a 2015–16 fishing season2015–16 fishing season2015–16 fishing season2016–17 fishing season2016–17 fishing season
Stock TAC
(t)
Catch
(t) (GHTS, CTS)
Real value (2015–16)
(GHTS, CTS)
TAC
(t)
Catch
(t) (GHTS, CTS)
Elephantfish16367
(35, 32)
<$0.10 million
(<$0.10 million, <$0.10 million)
16376
(45, 31)
Gummy shark1,8361,798
(1667, 131)
$16.31 million
($15.46 million, $0.85 million)
1,8361,669
(1526, 143)
Sawsharks482187
(93, 94)
$0.48 million
($0.26 million, $0.22 million)
482200
(112, 88)
School shark215 b181
(165, 16)
$1.58 million
($1.44 million, $0.14 million)
215 b173
(149, 24)
Total fishery 2,696 2,233
(1,960, 273)
$18.42 million
($17.21 million, $1.22 million)
2,696 2,118
(1832, 286)

Fishery-level statistics 2015–16 fishing season2016–17 fishing season
EffortGillnet: 29,876 km of net hauled
Hook: 1,695,313 hooks set
Gillnet: 31,814 km of net hauled
Hook: 1,103,912 hooks set
Fishing permits cGillnet: 61
Hook: 13
Gillnet: 61
Hook: 13
Active vesselsGillnet: 37
Hook: 26
Gillnet: 36
Hook: 26
Observer coverage dGillnet: 10%
Hook: 10%
Gillnet: 10%
Hook: 10%
Fishing methodsDemersal gillnet, demersal longline, dropline, mechanised handline, auto-longlineDemersal gillnet, demersal longline, dropline, mechanised handline, auto-longline
Primary landing portsAdelaide, Port Lincoln, Robe (South Australia); Devonport, Hobart (Tasmania); Lakes Entrance, San Remo, Port Welshpool (Victoria) Adelaide, Port Lincoln, Robe (South Australia); Devonport, Hobart (Tasmania); Lakes Entrance, San Remo, Port Welshpool (Victoria)
Management methodsInput controls: gear restrictions, closed areas
Output controls: ITQs, school shark/gummy shark catch ratio restriction, size limits, trip limits
Input controls: gear restrictions, closed areas
Output controls: ITQs, school shark/gummy shark catch ratio restriction, size limits, trip limits
Primary marketsDomestic: Melbourne, Adelaide and Sydney—fresh and frozenDomestic: Melbourne, Adelaide and Sydney—fresh and frozen
Management plan Southern and Eastern Scalefish and Shark Fishery Management Plan 2003 Southern and Eastern Scalefish and Shark Fishery Management Plan 2003

a Fishery statistics are provided by fishing season, unless otherwise indicated. Fishing season is 1 May to 30 April. Real-value statistics are by financial year and were not available for the 2016–17 financial year at the time of publication. Components of catch may not sum to total due to rounding. b Incidental catch allowance. c In the GHTS, additional permit types limit gear use and access to state waters. d Numbers of hooks observed relate only to the Shark Hook Sector. From 1 July 2015, e-monitoring is mandatory for all full-time vessels in the SGSHS. Video footage of at least 10% of all recorded hauls is reviewed to verify the accuracy of logbooks. In addition, gillnet boats operating off South Australia's Australian Sea Lion Zones are subject to 100% review of video footage for interactions with protected species.
Notes: CTS Commonwealth Trawl Sector. GHTS Gillnet, Hook and Trap Sector. ITQ Individual transferable quota. TAC Total allowable catch (for the entire Southern and Eastern Scalefish and Shark Fishery).

12.2 Biological status

Elephantfish (Callorhinchus milii)

Elephantfish (Callorhinchus milii) 

Line drawing: Karina Hansen

Stock structure

Stock structure of elephantfish is not known, and populations are considered to constitute a single stock for management purposes.

Catch history

Elephantfish contribute a small component (<5 per cent) of landed catch in the SGSHS. Catch of elephantfish in the SGSHS increased during the 1970s and peaked at almost 120 t in 1985 (Figure 12.4). Catch has since declined, and has been relatively stable at 30–60 t in recent years. Combined catch in 2016–17 in the Gillnet, Hook and Trap Sector (GHTS) and the Commonwealth Trawl Sector (CTS) increased slightly to 75 t (Table 12.2). The four-year rolling average (2012 to 2015) of elephantfish discards for state fisheries and the SGSHS was 140.9 t. In 2015, discards from the SGSHS only were 180.4 t, which is more than double the 2014 estimate (Thomson & Upston 2016). There is some uncertainty about the level of discards, especially for earlier years (AFMA 2012a). Discarding can be high in some areas of the fishery at certain times of the year. There is little information on recreational catches. The most recent stock assessment scenario accepted by the Shark Resource Assessment Group (SharkRAG) assumes that recreational catches increased from 29 t in 2002 to 45 t in 2008 and then remained at 45 t per year from 2008 to 2014 (Sporcic & Thomson 2015).

FIGURE 12.4 Annual elephantfish catch and fishing season TAC in the SGSHS, 1970 to 2016
Notes: TAC Total allowable catch. Actual TAC includes carryover from previous season (undercatch/overcatch). Discard data are only available by calendar year and for the period 2007 to 2014.
Stock assessment

Elephantfish has been assessed as a tier 4 stock under the SESSF harvest strategy framework since 2009. The tier 4 assessment framework uses standardised CPUE. The tier 4 assessment was revised in 2015 (Sporcic & Thomson 2015).

In 2014, SharkRAG recommended a decrease in the biomass target (BTARG) from 48 per cent to 40 per cent of unfished biomass (AFMA 2014a). In recommending the decrease in BTARG, SharkRAG noted that elephantfish was a byproduct species in the gillnet sector and that commercial catch largely depended on effort targeted at gummy shark (AFMA 2014a). As such, catch of elephantfish was not a key driver of the economics of the fishery, so a BMEY (biomass at maximum economic yield) proxy (B48) was not appropriate. SharkRAG further noted that they were not concerned about the sustainability of elephantfish. SharkRAG recommended the lower BTARG in 2015 (AFMA 2015a).

The most recent assessments of elephantfish (four alternative tier 4 assessments) in 2015 used data up to 2014. These assessments used scenarios including and excluding discards, and either constant recreational catches of 29 t or increased from 29 t in 2002 to 45 t in 2008 and then a constant 45 t per year from 2008 to 2014 (Sporcic & Thomson 2015). Trawl data were not analysed because of limited catch data, so only CPUE data from gillnet fishing were used. Concerns about the data used have been raised previously; the inclusion of discards was thought to bias estimates high, and the exclusion of discards was thought to bias estimates low (AFMA 2014b). All four assessments in 2015 estimated CPUE to be above the target (Sporcic & Thomson 2015).

Although the tier 4 assessment that included discards is thought to bias estimates high (AFMA 2014b), it was thought to more closely reflect the fishery dynamics (Sporcic & Thomson 2015). SharkRAG recommended using the tier 4 assessment that included discards in the CPUE with a BTARG of 0.4B0 (Figure 12.5) and the updated estimate of recreational catches to develop a recommended biological catch (RBC), since this was thought to be more conservative than other scenarios (AFMA 2015b). This resulted in an RBC of 306 t. TAC was constrained by the large change rule (which limits increases in TAC to 1.5 times the previous year's TAC). SharkRAG recommended a multiyear TAC for the 2015–16 to 2017–18 seasons of 163 t. In comparison, the landed catch of elephantfish in the 2016–17 season was 76 t.

FIGURE 12.5 Standardised gillnet CPUE index (including discards) for elephantfish in the SGSHS, 1997 to 2014
Notes: CPUE Catch-per-unit-effort. Discard data are only available by calendar year and for 2007 to 2014.
Source: Sporcic & Thomson 2015
Stock status determination

The average recent CPUE for elephantfish was estimated to be above the target and well above the limit reference points. On this basis, the stock is assessed as not overfished. Catch (excluding discards) in the 2016–17 season was below the TAC and below the RBC from the 2015 stock assessment. On this basis, the stock is assessed as not subject to overfishing.

Gummy shark (Mustelus antarcticus)

Gummy shark (Mustelus antarcticus) 

Line drawing: Karina Hansen

Stock structure

The most recent research on stock structure for gummy shark indicates that there are most likely two stocks in Australian waters: one in southern Australia, extending from Bunbury in Western Australia to Jervis Bay in New South Wales, and another in eastern Australia, extending from Newcastle to the Clarence River in New South Wales (White & Last 2008). The southern Australian biological stock is split into four populations for modelling purposes: the continental shelf of Bass Strait, Tasmania, South Australia and Western Australia. The first three are assessed together by the Commonwealth (Punt et al. 2016) and are reported here. The fourth is assessed separately by Western Australia (Braccini et al. 2013).

Catch history

Catch of gummy shark in the SGSHS increased after 1970, initially as byproduct in the school shark fishery, and then increasingly as a target as school shark catches decreased from 1986 (Figure 12.6). Catch in the SGSHS reached a peak of around 2,300 t in 1993. Catch dropped to a low of 1,288 t in 2012, before increasing since then to 1,667 t in 2015 and then decreasing slightly to 1,526 t in 2016 (Figure 12.6). Total Commonwealth catch (including from the CTS) in 2016–17 was 1,669 t. Estimates of discards have been stable in recent years, at 3–6 per cent of total catch. The four-year rolling average (2012 to 2015) of gummy shark discards for state fisheries and the SGSHS was 96 t (Thomson & Upston 2016).

FIGURE 12.6 Annual gummy shark catch and fishing season TAC in the SGSHS, 1970 to 2016
Notes: TAC Total allowable catch. Actual TAC includes carryover from previous season (undercatch/overcatch). Discard data are only available by calendar year and for 2007 to 2015.
Stock assessment

The most recent update of the integrated stock assessment model for gummy shark was in 2016, using data to the end of 2015 (Punt et al. 2016). Updated inputs to the assessment included landings data from 2013–15, revisions to earlier catch and length-frequency data, new age-frequency data and updated CPUE indices. Some changes to the model structure were also made, with catches by the different gear types now assumed to occur simultaneously, rather than sequentially; the ‘hook fleet' separated into its components; and made allowances for age-reading errors. As in previous assessments, Bass Strait, South Australian and Tasmanian stocks were treated as three separate populations, with no movement of animals between these regions and no density-dependent effects of one population on another. However, the stocks have a number of common biological parameters, including age–length and length–weight relationships, fecundity, gear selectivity, and overall availability as a function of age. The assessment uses pup production as an indicator of biomass because of the close relationship between pup production and female spawning biomass.

The gillnet closures off South Australia have influenced catch and CPUE of gummy shark in this area. When the 2014 update was run, there was concern that the South Australian CPUE data were less reliable as an index of abundance in recent years (Thomson & Sporcic 2014). Consequently, South Australian CPUE data after 2009 were not included in the 2014 update, a change that has been retained for the 2016 update.

The model treats the three regions separately and develops RBCs and pup production relative to P0 for each. These RBCs are then summed to an overall RBC. In addition, different gear types are known to have different selectivities, which result in differences in the average size of sharks caught. Consequently, a range of RBCs are calculated, based on different catch proportions taken by line and gillnet, which can be assessed against their impact on pup production at a regional level (Punt et al. 2016).

The base-case assessment estimated 2016 pup production as a proportion of the unfished level of pup production (1927) to be above 0.48P0 (48 per cent of virgin pup production) for all three gummy shark populations: 0.53P0 for Bass Strait (Figure 12.7a), 0.63 P0 for South Australia (Figure 12.7b) and 0.75 P0 for Tasmania (Figure 12.7c). These are all slightly reduced from the 2014 updated assessment (Thomson & Sporcic 2014). The sensitivities of the model to density dependence were examined through nine alternative models. Seven of the nine alternative models estimated pup production to be below 0.48P0 in Bass Strait (range 0.31P0 to 0.57P0), while the other models were all above 0.48P0 for South Australia (range 0.52P0 to 1.00P0) and Tasmania (range 0.59P0 to 0.79P0).

The three-year RBC for the base-case assessment resulted in an initial increase in RBC followed by reductions in each of the two following years. SharkRAG noted the importance of stable TACs for industry (AFMA 2016a) and requested that three additional scenarios be explored: the continuation of the current TAC, the average RBC when the base-case model is run to 2035, and the three-year average RBC from the base-case model (that is, when it is run to 2019). All three scenarios resulted in the Bass Strait population decreasing to below the target reference point by 2021 at the latest (continuation of the current TAC resulted in P2019 = 0.471P0 and was therefore discounted as an option). SharkRAG recommended that either the 2016–35 average RBC (1,961 t) or the 2016–19 average RBC (1,922 t) be applied as a three-year TAC. The group noted that, while either of these would provide stability for industry to 2019, the RBC would likely decrease when a new assessment is run in 2019 following fishing down to the target reference point (AFMA 2016b). The 2016–35 average RBC (1,961 t) was agreed to by the Australian Fisheries Management Authority (AFMA) Commission as the basis for a three-year TAC for the 2017–18 to 2019–20 seasons.

State allocations are deducted from the RBC (2.9 per cent of the RBC for catches in South Australian internal waters and 1.7 per cent of the RBC for catches in Victorian bays and inlets [AFMA 2013a]).

The Commonwealth catch of gummy shark in 2016–17 was 1,673 t, below the 2016–17 TAC. The catch was also below the 2017–18 RBC generated by the updated model.

FIGURE 12.7 Estimated pup production as a proportion of unfished level of pup production for gummy shark in (a) Bass Strait, (b) South Australia and (c) Tasmania, 1927 to 2016

 

 

Note: Scenario 1 refers to base-case scenario from the 2016 assessment.
Source: Punt et al. 2016
Stock status determination

The results of the 2016 stock assessment estimate that 2015 pup production (used as the index of gummy shark biomass) for each of the three subpopulations is above the target reference point (0.48P0) and well above the limit reference point. As a result, gummy shark is classified as not overfished. Since catch was less than the RBC generated by both the 2014 and 2016 models and the 2016–17 TAC, the stock is classified as not subject to overfishing.

Sawshark (Pristiophorus cirratus, P. nudipinnis)

Sawshark (Pristiophorus cirratus, P. nudipinnis) 

Line drawing: FAO

Stock structure

Three species of sawshark (common sawshark—Pristiophorus cirratus, southern sawshark—P. nudipinnis, and eastern sawshark—P. peroniensis) are caught in southern Australian waters. Little is known about the stock structure or movements of sawshark. Two species dominate reported sawshark catches in this sector: common sawshark and southern sawshark. For assessment purposes, all sawsharks found south of the Victoria – New South Wales border are assumed to be common or southern sawshark, and those found north of that border are assumed to be eastern sawshark (AFMA 2014c). Around 90 per cent of the total sawshark catch from southern Australia is taken from Bass Strait (AFMA 2011a). All sawshark catch in the SESSF is managed under a single TAC, and the status assessment is reported for the multispecies stock.

Catch history

Catch of sawshark in the SGSHS increased in the early 1970s to around 200 t by 1974, and then fluctuated between about 170 and 350 t per year until the early 2000s. Catch in the SGSHS declined steadily after 2004 and has remained below 100 t since 2012 (Figure 12.8). Combined catch in the SGSHS and the CTS in 2016–17 was 200 t (Table 12.2). The four-year rolling average (2012 to 2015) of sawshark discards for state fisheries and the SGSHS was 43.5 t. In 2015, discards from Commonwealth waters only were 35.4 t (Thomson & Upston 2016).

FIGURE 12.8 Sawshark catch and TAC in the SGSHS, 1970 to 2016
Notes: TAC Total allowable catch. Actual TAC includes carryover from previous season (undercatch/overcatch). Discard data are only available by calendar year and for the period 2007 to 2015.
Stock assessment

Sawshark has been assessed as a tier 4 stock under the SESSF harvest strategy framework since 2009. The most recent assessments of sawshark (four alternative tier 4 assessments) were conducted in 2015. The assessments used scenarios including and excluding discard estimates, and using either trawl or gillnet data. The assessments used data to 2014. The CPUE derived from the gillnet data was considered to be less reliable because of anecdotal reports of gillnet fishers actively avoiding sawshark (AFMA 2015b). The assessments based on trawl data have been used in recent years because they are considered to be less affected by avoidance (AFMA 2014b, 2015d). The assessment that excluded discard data was used for status determination because the uncertainty in discard data was thought to result in an overestimate of CPUE (AFMA 2015d).

In 2014, SharkRAG recommended a decrease in the biomass target (BTARG) from 48 per cent to 40 per cent of unfished biomass. Since sawshark is currently a byproduct species in the gillnet sector, SharkRAG noted that commercial catch largely depends on effort targeted at gummy shark (AFMA 2014a). As such, catch of sawshark was not a key driver of the economics of the fishery, so a BMEY proxy (B48) was not appropriate. SharkRAG further noted that it was not concerned about the sustainability of sawshark and recommended a decrease in BTARG for the species (AFMA 2014a). SharkRAG recommended retaining the biomass target of 0.4B0 in 2015 (AFMA 2015a). The tier 4 assessment based on trawl data, excluding discards with a BTARG of 0.4B0, gave an RBC of 535 t before the tier 4 discount factor (15 per cent discount) was applied (Sporcic & Thomson 2015).

SharkRAG recommended a TAC for the 2015–16 to 2017–18 seasons of 482 t. In comparison, the landed catch of sawshark in the 2016–17 season was 200 t.

Stock status determination

The average recent CPUE for sawshark was estimated to be above the target reference point and well above the limit reference point (Figure 12.9). On this basis, the stock is assessed as not overfished. Catch in the 2016–17 season was below the TAC and below the RBC from the 2015 stock assessment. On this basis, the stock is assessed as not subject to overfishing.

FIGURE 12.9 Standardised CPUE index for sawshark in the CTS, 1997 to 2014 (trawl)
Note: CPUE Catch-per-unit-effort.
Source: Haddon 2014

School shark (Galeorhinus galeus)

School shark (Galeorhinus galeus) 

Line drawing: Karina Hansen

Stock structure

School shark has a broad distribution throughout temperate waters of the eastern North Atlantic, western South Atlantic, and north-eastern and south-eastern Pacific oceans; and temperate waters off South Africa, New Zealand and southern Australia. A single genetic stock exists in Australian waters, and school shark is managed as a single stock in the SESSF area.

Catch history

Catch of school shark in the SGSHS peaked at more than 2,500 t in 1970 and then declined rapidly to around 500 t in 1973. Catch in the sector again increased, to around 2,000 t in 1986, before declining steadily through the late 1980s and 1990s, and then stabilising from 2000 onwards at around 200 t per year (Figure 12.10). In 2009, the species was listed as conservation dependent under the Environment Protection and Biodiversity Conservation Act 1999 and has been subject to other measures to reduce catch, including the implementation of a catch ratio of 20 per cent school shark to gummy shark—whereby a fisher must hold five times more gummy shark quota than their school shark catch (2011–12 season)—and the requirement that all live caught school shark be released (2014–15 season). Catch in 2016–17 was 173 t. The four-year rolling average (2012 to 2015) of school shark discards for both state and Commonwealth waters was 34.4 t. In 2015, discards from Commonwealth waters only were 32.7 t, a decrease of 10 t from 2014 (Thomson & Upston 2016).

FIGURE 12.10 Annual school shark catch and fishing season TAC in the SGSHS, 1970 to 2016
Notes: TAC Total allowable catch. Actual TAC includes carryover from previous season (undercatch/overcatch).Discard data are only available by calendar year and for 2007 to 2015.
Stock assessment

School shark has been considered to be below the 0.2B0 limit since about 1990. The base case of the most recent full stock assessment in 2009, using data to 2008, estimated the biomass at 0.12B0 (Thomson & Punt 2009). In 2012, the 2009 assessment was re-run with additional catch data for 2009 to 2012 (Thomson 2012), specifically to estimate recovery time frames for the stock under a range of future incidental catch levels and to investigate the impact of a proposed auto-longline shark fishery in South Australia. Under a zero catch scenario, the stock was projected to rebuild to 0.2B0 within 23 years. At a constant catch of 250 t, the stock was projected to rebuild to 0.2B0 in 80 years, and a constant catch of 275 t was projected to collapse the stock. These projections were based on assumptions that the gear selectivity, and spatial and temporal distribution of catches remain similar to those in 2011. Uncertainties around these median projections were not provided by the assessment. The school shark rebuilding strategy was revised in 2015 to explicitly specify a recovery time frame of 66 years to the 0.2B0 limit (AFMA 2015c), based on advice from SharkRAG.

The reliability of the current school shark stock assessment model to estimate the state of the stock is limited, as a result of increasingly uncertain input data over the past decade. The low TACs in recent years and the reported avoidance behaviour of gillnet fishers have meant that the CPUE index for that sector has potentially become less reliable as an index of abundance. The coefficient of variance associated with the fishery-independent survey data is also very high.

There are indicators that school shark biomass may be increasing. These include a preliminary index of abundance based on trawl CPUE, which estimates a generally increasing trend (Sporcic 2016). Trawl CPUE data may be a better representation of biomass than CPUE from other methods, because trawl does not target, nor can it avoid, school shark (AFMA 2016c); however, it is unclear how reliable an index of abundance trawl CPUE is, because the trawl fishery primarily operates outside the main part of the gummy shark fishery (AFMA 2016a). Data from the Integrated Scientific Monitoring Program (ISMP) show an increase in the catch of small school sharks (Thomson et al. 2015). Preliminary results of survey work by the Institute for Marine and Antarctic Studies (IMAS) in school shark pupping areas off Tasmania indicate higher numbers of pups than during the 1990s (McAllister et al. 2015). Industry participants on SharkRAG have reported signs of increasing availability of school shark, including increasing presence of juvenile school shark and increasing difficulty in avoiding school shark (AFMA 2014a, c; 2013b).

A project to develop a fishery-independent index of abundance using close-kin genetic approaches is currently underway, and should further inform rebuilding targets and time frames when results become available (by the end of 2017) (AFMA 2013c, 2016a). A new stock assessment will be run after results from the close-kin genetics project are finalised (likely in 2018) (AFMA 2016a).

The reported landed catch in the SGSHS in 2016–17 was 173 t, a decrease from the 2015–16 catch of 181 t and below the incidental catch allowance of 215 t. State catches and discards are not available by season; however, in the 2015 calendar year, discards from the SGSHS were 15 per cent of catch (32.7 t; Thomson & Upston 2016). Overall, state catches in 2015 were higher than in 2014 (24 t in 2015; 22 t in 2014), with South Australia reporting most (17 t) of this. South Australia's catch continues to exceed its allocation of 6.2 t under the Offshore Constitutional Settlement.

Stock status determination

The last full stock assessment of school shark, undertaken in 2009, estimated the 2008 biomass to be below the limit reference point. Projections of this model undertaken in 2012 indicate that the stock was likely to recover to a level above the limit reference point in 2035 if the catch was zero. School shark catches have been between 129 t and 230 t in each year since these analyses were run. The stock therefore remains classified as overfished.

Commonwealth discards and state catches are only available for the 2015 calendar year. Additionally, state discards are not known. If state catches in 2016–17 were similar to those in recent years, and similar to discards from the SGSHS, total catch (retained and discarded) from the SGSHS and state fisheries may have been around 230 t. A constant catch of 250 t was estimated to enable recovery to the limit reference point within 80 years, while a catch of 275 t was projected to collapse the stock.

Some evidence indicates that the stock may be rebuilding under current catches (for example, trawl CPUE, IMAS surveys, ISMP data and anecdotal reports from industry). However, there is uncertainty around total catch estimates for the 2016–17 season, because South Australian catch has consistently increased in recent years, and the latest available state and discarding data relate to the 2015 calendar year. In addition, there is uncertainty around the rebuilding projections resulting from uncertainty in the stock assessment. Given these issues, whether the level of fishing mortality will enable rebuilding within the time frame is uncertain, and school shark is therefore classified as uncertain with regard to the level of fishing mortality.

12.3 Economic status

Key economic trends

The real gross value of production (GVP) in the SGSHS, which reflects the four shark species taken in the GHTS, declined from a peak of $26.74 million in 2008–09 to $18.42 million in 2015–16 (Figure 12.11). This long-term fall is primarily the result of a 27 per cent fall in the price of gummy shark, despite experiencing a slight (2 per cent) increase in volume. Since 2013–14, GVP for the SGSHS has trended upwards, largely as a result of higher volumes of gummy shark landings. Gummy shark accounts for the majority of GVP in the SGSHS (89 per cent in 2015–16).

FIGURE 12.11 Real GVP for the SGSHS, by key species, and real price for gummy shark, 2005–06 to 2015–16
Note: GVP Gross value of production.

The four shark species that make up the SGSHS—gummy shark, school shark, sawshark and elephantfish—account for around 77 per cent of the GHTS GVP, with scalefish species making up the remainder. Therefore, overall economic performance in the GHTS may contribute to an understanding of economic status in the SGSHS.

Survey-based estimates of revenue, costs and net economic returns (NER) in the GHTS are available for 2012–13, and preliminary estimates are available for 2013–14 (Figure 12.12). NER in the GHTS were positive between 2003–04 and 2008–09, peaking at $7.04 million in 2008–09 (Figure 12.13). NER reached a low of −$5.55 million in 2011–12. Preliminary estimates for 2013–14 indicate that NER are likely to remain negative. The falling price of fuel is unlikely to improve NER, as the price of fuel is not a significant input in gillnet and hook fisheries, unlike in trawl fisheries.

FIGURE 12.12 Real revenue and costs for the GHTS, 2003–04 to 2013–14
Note: Data for 2013–14 are preliminary.
Source: Skirtun & Green 2015
FIGURE 12.13 Real NER for the GHTS, 2003–04 to 2013–14
Notes: NER Net economic returns. NER estimates for 2013–14 are preliminary non–survey based estimates.
Source: Skirtun & Green 2015

A profit decomposition of the gillnet sector of the GHTS (Skirtun & Vieira 2012) showed that the key driver of profitability in the sector in the period 2006–07 to 2008–09 was productivity growth. This was linked to the Securing our Fishing Future structural adjustment package (completed in 2006–07), which is considered to have removed the least efficient vessels from the sector (Vieira et al. 2010). The decline in NER in recent years can be partly linked to falls in the price of fish within the fishery. Productivity has improved recently, but this has been offset by falls in the terms of trade for fishers, providing downward pressure on NER (Skirtun & Green 2015). Factors related to recent management changes in the fishery (discussed below) are also likely to have played a role.

Management arrangements

Significant spatial closures have been implemented in recent years to reduce the catch of protected species, primarily in South Australian waters (see Chapter 8). This started with voluntary closures in 2009–10, followed by mandatory closures in 2010–11. As a result, it is likely that fisher incentives have changed, leading to a relocation of fishing intensity to other areas, particularly for operators where closures have covered the full extent of their usual fishing grounds. Some South Australian gillnet fishers also operate in the South Australian Rock Lobster Fishery, which is considered to be profitable (Econsearch 2014) and could have supported some SGSHS operators affected by the closures. However, these changes would have reduced the profitability of gillnet operations in South Australia, contributing to the negative NER in the GHTS following the closures.

South Australian gillnet operators (subject to specific qualification criteria) are allowed to use hook methods in areas where gillnetting is prohibited (or restricted), so that fishers can continue to operate. However, anecdotal reports from industry suggest that vessel-level economic efficiency is lower using this hook method (AFMA 2011b). Anecdotal information also indicates that allowing gillnet permit holders to use hooks has had a negative impact on the value of hook permits in the sector, as rights provided by hook permits have become less exclusive. One adaptive management zone (zone C) was closed in 2016 (reopened 18 June 2017).

School shark biomass remains below the limit reference point, and stock rebuilding measures are likely to be affecting sector profitability. These measures include low incidental catch allowances and the prohibition of targeted fishing. Given the relatively high beach prices of school shark, changes in its catch allowance can have a relatively large influence on the revenue of the sector. Additionally, school shark is often caught with gummy shark, the main target species of the sector. Operators who do not hold quota for school shark, or actively avoid it when targeting gummy shark, are forfeiting a potential means of profit. The substantial time projected for school shark stock rebuilding means that it may be some time before these issues are resolved.

Trials to test the efficiency of longer gillnets (4,200–6,000 m) have been undertaken; SharkRAG, in January 2016, considered the preliminary results inconclusive (AFMA 2016d). Giving fishers the option to use longer nets provides them with greater flexibility to operate under individual transferable quotas, potentially improving efficiency and NER. However, some industry members previously expressed concerns about introducing larger nets at a time when the sector is already facing significant challenges to reduce bycatch (AFMA 2011b). The AFMA Commission has since approved the removal of net length restrictions, subject to the roll-out of dolphin management arrangements across the fishery.

Performance against economic objective

Additional information on the economic status of the SGSHS is possible by comparing the biomass levels of key species with harvest strategy targets. Gummy shark is the primary driver of economic performance in the SGSHS, accounting for 89 per cent of the SGSHS GVP in 2015–16. The target reference point for gummy shark is the BMEY proxy of 0.48P0 (48 per cent of virgin pup production). The results of the 2013 stock assessment indicate that the biomass for gummy shark stocks is likely to be above the target reference point. If the proxy accurately reflects BMEY for this species, the results indicate that biomass is not currently constraining NER and that there may be potential for expansion in the sector.

The SGSHS is a multispecies fishery, and its economic performance must also be interpreted in terms of the other species caught in the fishery. The incidental catch allowance for school shark makes it the second most valuable species in the sector, accounting for 9 per cent of SGSHS GVP in 2015–16. The school shark to gummy shark quota restriction implemented in 2011–12 may have reduced gummy shark catch and therefore current GVP (AFMA 2014d). Efforts to rebuild the school shark stock towards target levels should lead to future increases in NER.

The challenge of reducing marine mammal interactions may affect the degree to which economic performance can be improved in the short term. Recent closures to mitigate interactions are likely to have contributed to the recently observed declines in the GHTS NER and may be related to increased gummy shark quota latency since 2009. The falling price of gummy shark is another contributor to the reduced gummy shark catch since 2009.

Demersal longline hooks
AFMA

12.4 Environmental status

The SESSF was accredited against parts 13 and 13A of the Environment Protection and Biodiversity Conservation Act 1999 in February 2016. Conditions associated with the accreditation relate to the impact of fishing on bycatch species, particularly Australian sea lions (Neophoca cinerea), dolphins, seals and seabirds. Further recommendations associated with the accreditation relate to requirements for ecological risk assessment, and monitoring of bycatch and discarding.

A level 2 ecological risk assessment of 329 species resulted in 21 assessed as being at high risk (16 chondrichthyans and 5 marine mammals; Walker et al. 2007). A level 3 Sustainability Assessment of Fishing Effects (SAFE) assessment was completed for all 195 chondrichthyan and teleost species identified in the shark gillnet fishery, regardless of their level 2 Productivity Susceptibility Analysis (PSA) risk score. The assessment found seven species (all chondrichthyan) to be at high risk (Zhou et al. 2012). One species (common sawshark—Pristiophorus cirratus) was removed during the residual risk analysis (AFMA 2014e). The remaining six species considered to be at high risk are all sharks: bronze whaler (Carcharhinus barchyurus), white shark (Carcharodon carcharias), whiskery shark (Furgaleus macki), smooth hammerhead shark (Sphyrna zygaena), school shark (Galeorhinus galeus) and broadnose sevengill shark (Notorynchus cepedianus). A 2010 residual risk assessment of PSA results for non-teleost and non-chondrichthyan species identified five marine mammal species as high risk (AFMA 2010). A subsequent residual risk analysis removed two species (as a result of no interactions being recorded in the fishery) and included one further species (as a result of higher than expected interactions), resulting in four marine mammal species considered to be at high risk in the fishery: Australian fur seal (Arctocephalus pusillus doriferus), Australian sea lion, New Zealand fur seal (A.forsteri) and common dolphin (Delphinus delphis) (AFMA 2012b). The results of the ecological risk assessments have been consolidated to form a priority list in an ecological risk assessment strategy for the SESSF (AFMA 2015d).

AFMA publishes quarterly reports of logbook-reported interactions with protected species on its website. Reports for the GHTS in the 2016 calendar year indicate 349 interactions: 76 with mammals, 143 with seabirds, and the remainder with sharks. The mammal interactions comprised 37 interactions with dolphins (2 alive; 34 dead; 1 in unknown condition), 10 with Australian fur seals (all dead), 2 with Australian sea lions (1 dead), 6 with New Zealand fur seals (all dead), 1 with a killer whale (dead) and 20 with seals (3 unclassified; 17 dead). In 2016, 143 seabirds (21 of which were released alive) were caught, including albatrosses, cormorants, petrels, prions and shearwaters, and gannets.

Logbooks reported that 101 shortfin mako sharks (3 alive; 89 dead; 7 injured; 2 unknown condition), 17 porbeagle sharks (6 injured; 11 dead), 1 grey nurse shark (dead) and 11 great white sharks (9 alive; 1 dead; 1 unknown condition) were caught during 2016. Measures to reduce interactions with Australian sea lions and dolphins are discussed in Chapter 8.

12.5 References

AFMA 2009, Harvest strategy framework for the Southern and Eastern Scalefish and Shark Fishery, version 1.2, September 2009, Australian Fisheries Management Authority, Canberra.

—— 2010, Residual risk assessment of the level 2 ecological risk assessment species results: report for the gillnet sector of the Gillnet, Hook and Trap Fishery, AFMA, Canberra.

—— 2011a, SharkRAG species summaries 2010, AFMA, Canberra.

—— 2011b, ‘South East Management Advisory Committee (SEMAC), chair's summary, meeting 7, 19 September 2011', AFMA, Canberra.

—— 2012a, ‘Shark Resource Assessment Group (SharkRAG) meeting record, 13–14 November 2012', AFMA, Canberra.

—— 2012b, Residual risk assessment of the level 2 productivity susceptibility assessment: report for the shark gillnet method of the Gillnet, Hook and Trap sector, AFMA, Canberra.

—— 2013a, ‘South East Management Advisory Committee (South East MAC) teleconference minutes, 18 March 2013', AFMA, Canberra.

—— 2013b, ‘Shark Resource Assessment Group (SharkRAG) meeting record, 8 March 2013', AFMA, Canberra.

—— 2013c, ‘Shark Resource Assessment Group (SharkRAG) meeting record, 2–3 October 2013', AFMA, Canberra.

—— 2014a, ‘Shark Resource Assessment Group (SharkRAG) meeting record, 15–16 October 2014', AFMA, Canberra.

—— 2014b, ‘Shark Resource Assessment Group (SharkRAG) meeting record, 20 November 2014', AFMA, Canberra.

—— 2014c, Species summaries for the Southern and Eastern Scalefish and Shark Fishery: for stock assessments completed in 2013 in preparation for the 2014–15 fishing season, AFMA, Canberra.

—— 2014d, Southern and Eastern Scalefish and Shark Fishery management arrangements booklet 2014, AFMA, Canberra.

—— 2014e, Residual risk assessment: report for the shark gillnet method of the Gillnet, Hook and Trap sector, AFMA, Canberra.

—— 2015a, ‘Shark Resource Assessment Group (SharkRAG) meeting minutes, 18–19 November 2015', AFMA, Canberra.

—— 2015b, ‘Shark Resource Assessment Group (SharkRAG) meeting minutes, 8 October 2015', AFMA, Canberra.

—— 2015c, School shark Galeorhinus galeus stock rebuilding strategy: revised 2015, AFMA, Canberra.

—— 2015d, Ecological risk management: strategy for the Southern and Eastern Scalefish and Shark Fishery, AFMA, Canberra.

—— 2016a, ‘Southern and Eastern Scalefish and Shark Fishery Shark Resource Assessment Group (SharkRAG) meeting minutes, 22–23 November 2016', AFMA, Canberra.

—— 2016b, ‘Southern and Eastern Scalefish and Shark Fishery Shark Resource Assessment Group (SharkRAG) meeting minutes, 7 December 2016', teleconference, AFMA, Canberra.

—— 2016c, ‘Shark Resource Assessment Group (SharkRAG) meeting no.1 2016 meeting minutes, 13–14 October 2016', AFMA, Canberra.

—— 2016d, ‘Shark Resource Assessment Group (SharkRAG) out of session teleconference, meeting minutes, 28 January 2016', AFMA, Canberra.

Braccini, M, McAuley, R & Rowland, F 2013, ‘Temperate Demersal Gillnet and Demersal Longline fisheries status report', in WJ Fletcher & K Santoro (eds), Status reports of the fisheries and aquatic resources of Western Australia 2012/13, Department of Fisheries, Perth.

Econsearch 2014, Economic indicators for the SA Southern Zone Rock Lobster Fishery 2012/13, report prepared for Primary Industries and Resources South Australia, Econsearch, Adelaide.

Haddon, M 2014, SESSF saw shark and elephantfish tier 4 analyses (data from 1986–2013), CSIRO, Hobart.

Knuckey, I, Ciconte, A, Koopman, M, Hudson, R & Rogers, P 2014, Trials of longlines to target gummy shark in SESSF waters off South Australia: FRDC project 2011/068, Fishwell Consulting, Queenscliff.

McAllister, JD, Barnett, A, Lyle, JM & Semmens, JM 2015, ‘Examining the functional role of current area closures used for the conservation of an overexploited and highly mobile fishery species', ICES Journal of Marine Science, vol. 72, no. 8, pp. 2234–44.

Punt, A, Thomson, R & Sporcic, M 2016, Gummy shark assessment update for 2016, using data to the end of 2015, report presented to the SharkRAG meeting, CSIRO Marine and Atmospheric Research, Hobart.

Skirtun, M & Vieira, S 2012, Understanding the drivers of profitability in Commonwealth fisheries, ABARES technical report 12.4, ABARES, Canberra.

—— & Green, R 2015, Australian fisheries economic indicators report 2015: financial and economic performance of the Southern and Eastern Scalefish and Shark Fishery, ABARES, Canberra.

Sporcic, M & Thomson, R 2015, Tier 4 analyses for elephant fish and sawshark in the SESSF: (data to 2014), CSIRO Marine and Atmospheric Research, Hobart.

—— 2016, CPUE standardization for selected shark SESSF species (data to 2015): Draft, SharkRAG Meeting 1: 13–14 October, 2016, CSIRO Marine and Atmospheric Research, Hobart.

Thomson, R 2012, Projecting the school shark model into the future: rebuilding timeframes and auto-longlining in South Australia, CSIRO Marine and Atmospheric Research, Hobart.

—— & Punt, AE 2009, Stock assessment update for school shark Galeorhinus galeus based on data to 2008, report presented to the SharkRAG meeting, 17–18 November, CSIRO Marine and Atmospheric Research, Hobart.

—— & Sporcic, M 2014, Gummy shark assessment update for 2013, using data to the end of 2012 (draft), CSIRO Marine and Atmospheric Research, Hobart.

——, Sporcic, M, Klaer, N, Fuller, M, Krucic-Golub, K & Upston, J 2015, Data summary for the Southern and Eastern Scalefish and Shark Fishery: logbook, landings and observer data to 2014 (draft), CSIRO Marine and Atmospheric Research, Hobart.

—— & Upston, J 2016, SESSF catches and discards for TAC purposes, CSIRO Marine Resources and Industries, Hobart.

Vieira, S, Perks, C, Mazur, K, Curtotti, R & Li, M 2010, Impact of the structural adjustment package on the profitability of Commonwealth fisheries, Australian Bureau of Agricultural and Resource Economics research report 10.01, ABARE, Canberra.

Walker, T, Stone, T, Battaglene, T & McLoughlin, K 1994, The southern shark fishery 1994, fisheries assessment report compiled by the Southern Shark Fishery Assessment Group.

——, Dowdney, J, Williams, A, Fuller, M, Webb, H, Bulman, C, Sporcic, M & Wayte, S 2007, Ecological risk assessment for the effects of fishing: report for the shark gillnet component of the Gillnet, Hook and Trap Sector of the Southern and Eastern Scalefish and Shark Fishery, report for AFMA, Canberra.

White, WT & Last, PR 2008, ‘Description of two new species of gummy sharks, genus Mustelus (Carcharhiniformes: Triakidae), from Australian waters', in PR Last, WT White & JJ Pogonoski (eds), Descriptions of new Australian chondricthyans, CSIRO Marine and Atmospheric Research paper 22, CSIRO Marine and Atmospheric Research, Canberra.

Zhou, S, Fuller, M & Daley, R 2012, Sustainability assessment of fish species potentially impacted in the Southern and Eastern Scalefish and Shark Fishery: 2007–2010, CSIRO, Canberra.

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Last reviewed:
13 Feb 2018