International Fisheries

​​​Chapter 20: International fishery management arrangements

H Patterson

FIGURE 20.1 Areas of competence for regional fisheries management organisations

Notes: CCAMLR Commission for the Conservation of Antarctic Marine Living Resources. CCSBT Commission for the Conservation of Southern Bluefin Tuna. EEZ Exclusive Economic Zone. IOTC Indian Ocean Tuna Commission. RFMO Regional fisheries management organisation. SIOFA Southern Indian Ocean Fisheries Agreement. SPRFMO South Pacific Regional Fisheries Management Organisation (see Chapter 28 for full extent). WCPFC Western and Central Pacific Fisheries Commission. IOTC and WCPFC areas of competence include EEZs.

Several fish stocks of commercial importance to Australia have ranges extending outside the Australian Fishing Zone (AFZ) into the high seas and the Exclusive Economic Zones (EEZs) of other countries. These stocks are important for Australia in providing a source of economic benefits for the Australian fishing industry, and require regional cooperative action for effective management. Management responsibility is shared by multiple governments through international instruments (conventions and agreements), which are often implemented through a regional fisheries management organisation (RFMO) or other international body (Figure 20.1). As a party to these international instruments, Australia implements measures agreed by the relevant body in managing its domestic fishery; in a number of cases, Australia's domestic standards exceed those agreed internationally. Australia's continued engagement in international fisheries processes is critical to supporting access for the Australian fishing industry, and promoting responsible management to ensure sustainability of the fisheries and the ecosystems that support them.

This chapter provides an introduction to international fisheries arrangements to which Australia is a party. Status reports of the domestic fisheries involved are provided in Chapters 21–28. Although the fisheries of Torres Strait are also managed under an international agreement, they differ substantially from the fisheries described here and are therefore addressed separately in Chapters 15–19.

Through participation in RFMOs and other international fisheries bodies, Australia aims to implement its commitments and obligations under overarching international instruments, including the:

  • 1982 United Nations Convention on the Law of the Sea (UNCLOS)
  • 1995 Agreement for the Implementation of the Provisions of the UNCLOS relating to the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks (UN Fish Stocks Agreement)
  • 1995 United Nations Food and Agriculture Organization (FAO) Code of Conduct for Responsible Fisheries
  • 1995 Agreement to Promote Compliance with International Conservation and Management Measures by Fishing Vessels on the High Seas
  • 2006 and 2009 United Nations General Assembly (UNGA) Resolutions on Sustainable Fisheries (UNGA 61/105, UNGA 64/72)
  • 2009 Agreement on Port State Measures to Prevent, Deter and Eliminate Illegal, Unreported and Unregulated Fishing.

Globally, the species targeted on the high seas vary by area and fishing fleet. Some of the most extensive high-seas fisheries are pelagic fisheries catching highly migratory tunas, billfishes and sharks (defined under UNCLOS Annex 1). Currently, five conventions or agreements have been established to manage such species and species groups; Australia is party to three of these:

  • Convention on the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean
  • Convention for the Conservation of Southern Bluefin Tuna
  • Agreement for the Establishment of the Indian Ocean Tuna Commission.

Australia has also participated in the development of newer agreements where there are gaps in the international management of other non–highly migratory stocks in the high seas. Australia is party to the:

  • Southern Indian Ocean Fisheries Agreement (SIOFA)
  • Convention on the Conservation and Management of High Seas Fishery Resources in the South Pacific Ocean.

Arrangements for demersal species in Antarctic waters, and for the AFZ of Heard Island and McDonald Islands, are implemented through the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). The AFZ of Macquarie Island is adjacent to the CCAMLR convention area, rather than within it. However, for consistency, the Macquarie Island Toothfish Fishery is managed in line with CCAMLR arrangements.

The Commonwealth Fisheries Harvest Strategy Policy (HSP; DAFF 2007) requires that harvest strategies be developed for all Commonwealth fisheries, apart from those that are managed under the joint authority of the Australian Government and another Australian jurisdiction, or an international management body or arrangement. However, the policy notes that the Australian Government will advocate the principles of the policy when negotiating with these bodies. The Commission for the Conservation of Southern Bluefin Tuna (CCSBT) adopted a management procedure in 2011, which is analogous to a harvest strategy (Chapter 23). There has also been considerable progress in the adoption of harvest strategy principles and revised reference points in the Indian Ocean Tuna Commission (IOTC), and the Western and Central Pacific Fisheries Commission (WCPFC) over recent years. The scientific committees of some RFMOs report against reference points for biomass and fishing mortality when providing advice on stock status. These may be defined differently from those in the HSP, although in the case of the WCPFC and the IOTC the limit reference points adopted are the same as prescribed in the HSP. For jointly managed stocks, ABARES determines stock status in light of the limit reference points described in the HSP and considers the impacts of fishing mortality from all fleets on the stocks.

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20.1 Regional fisheries management organisations

Western and Central Pacific Fisheries Commission

The WCPFC is responsible for the world's largest and most valuable tuna fishery. In 2015, the total tuna catch of the fishery was worth more than US$4.8 billion and constituted about 56 per cent of the global tuna catch. The WCPFC area of competence includes the EEZs of many developing Pacific island states (Figure 20.1), for which tuna fishing is a significant source of income. The WCPFC has a specific mandate to manage fishing impacts on all highly migratory fish species listed in UNCLOS Annex 1, except sauries (Scomberesocidae). See Chapter 21 for more information.

Commission for the Conservation of Southern Bluefin Tuna

The Convention for the Conservation of Southern Bluefin Tuna, which established the CCSBT, originated from discussions between Australia, Japan and New Zealand in the mid 1980s, following an observed decline in stock biomass. The convention applies to southern bluefin tuna (Thunnus maccoyii) throughout its range,rather than within a specified geographic area. Therefore, it covers areas of the Indian, Atlantic and Pacific oceans (Figure 21.1), overlapping with the areas of competence of the CCAMLR, the WCPFC and the IOTC. The CCSBT's primary management measure is a global total allowable catch (TAC), which is allocated to members and cooperating non-members. Currently, Australia, Japan, New Zealand, the Republic of Korea and the Fishing Entity of Taiwan hold the majority (93 per cent) of the global TAC. See Chapter 23 for more information.

Indian Ocean Tuna Commission

The IOTC is an intergovernmental organisation established under the Agreement for the Establishment of the Indian Ocean Tuna Commission, and is an article XIV body of the FAO. It is mandated to manage tuna and tuna-like species in the Indian Ocean and adjacent seas (Figure 21.1). The IOTC's area of competence covers a large number of countries, and both artisanal and industrial fishing vessels. Membership of the IOTC is open to Indian Ocean coastal countries, and countries or regional economic integration organisations that are members of the United Nations or one of its specialised agencies that actively fish for tunas in the Indian Ocean. The IOTC is responsible for the world's second-largest tuna fishery in terms of both volume and value. The Indian Ocean differs from other oceans in that small-scale or artisanal fisheries take around the same quantity of tuna as industrial fisheries; much of this catch is neritic (inshore) tuna-like species, which are under IOTC management. See Chapter 24 for more information.

Commission for the Conservation of Antarctic Marine Living Resources

The CCAMLR was established to conserve and manage the Southern Ocean Antarctic ecosystem, mainly in high-seas areas. It originated from concern over the effects of fishing for krill (Euphausia superba) on the broader Antarctic ecosystem. The objective of the CCAMLR is the conservation and rational use of Antarctic marine living resources. In managing fisheries within its area of competence, the CCAMLR uses harvest strategies that specifically incorporate ecological links in setting TACs. Such an approach views the entire Southern Ocean as a suite of interlinked ecological systems—this distinguishes the CCAMLR from the other multilateral fisheries conventions. The strategies result in conservative TACs that aim to reduce the potential effects of fishing on other species, such as predators of the target species. There is also a focus on mitigating impacts on the benthic environment and bycatch, particularly seabirds. Fisheries in the CCAMLR convention area are required to have high levels of observer coverage, data collection and reporting, and there are specific requirements for new or exploratory fisheries. See Chapters 25 and 27 for more information.

Southern Indian Ocean Fisheries Agreement

The SIOFA entered into force on 21 June 2012. The objectives of the agreement are to ensure the long-term conservation and sustainable use of the non–highly migratory fisheries resources in the SIOFA area of competence through cooperation among the parties. The agreement promotes the sustainable development of fisheries in the area, taking into account the needs of developing states bordering the area that are parties to the agreement—in particular, the small-island developing states. See Chapter 28 for more information.

South Pacific Regional Fisheries Management Organisation

The Convention on the Conservation and Management of High Seas Fishery Resources in the South Pacific Ocean entered into force on 24 August 2012. The convention, which is implemented by the South Pacific Regional Fisheries Management Organisation, covers non–highly migratory fisheries resources in the southern Pacific Ocean. The area has been fished by vessels from numerous countries, using both pelagic and demersal gear. The largest fisheries focus on pelagic species in upwelling areas of higher productivity off the west coast of South America. Other fisheries target demersal species found on seamounts and ridges in the central and western areas of the southern Pacific Ocean. See Chapter 28 for more information.

20.2 References

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

Tuna processing in Indonesia
Heater Patterson, ABARES

Chapter 21: Eastern Tuna and Billfish Fishery

J Larcombe, H Patterson and J Savage

FIGURE 21.1 Relative fishing intensity in the Eastern Tuna and Billfish Fishery, 2016
TABLE 21.1 Status of the Eastern Tuna and Billfish Fishery
Status
Biological status
2015
Fishing mortality
2015
Biomass
2016
Fishing mortality
2016
Biomass
Comments a
Striped marlin (Kajikia audax), south-west PacificNot subject to overfishingNot overfishedNot subject to overfishingNot overfishedMost recent estimate of spawning biomass (2012) is above the default limit reference point of B20 but below BMSY. Current fishing mortality rate is below MSY levels.
Swordfish (Xiphias gladius), south-west PacificUncertainNot overfishedUncertainNot overfishedMost recent estimates of biomass (2013) are above the default limit reference point of B20. Fishing mortality estimates vary depending on uncertain growth schedule.
Albacore (Thunnus alalunga), south PacificNot subject to overfishingNot overfishedNot subject to overfishingNot overfishedMost recent estimate of spawning biomass (2015) is above the default limit reference point. Recent ocean-wide catches are at, or slightly less than, MSY, and fishing mortality is below MSY levels.
Bigeye tuna (Thunnus obesus), western and central PacificSubject to overfishingOverfishedSubject to overfishingOverfishedMost recent estimate of spawning biomass (2014) is below the limit reference point. Ocean-wide catches exceed MSY, and current fishing mortality rate exceeds that required to produce MSY.
Yellowfin tuna (Thunnus albacares), western and central PacificNot subject to overfishingNot overfishedNot subject to overfishingNot overfishedMost recent estimate of biomass (2014) is above the limit reference point. Ocean-wide estimates of fishing mortality are below MSY levels.

Economic status
NER remained positive in 2013–14 (preliminary estimate) and for 2014–15 are likely to have increased as a result of higher GVP, lower fuel prices and reduced latency. In 2015–16, NER are likely to have increased further as prices for all major species increased significantly. The implementation of individual transferable quotas and a harvest strategy for some stocks is likely to be supporting increases in NER; however, neither have been implemented long enough to determine whether there has been a positive effect.

a Regional assessments of species and the default limit reference points from the Commonwealth Fisheries Harvest Strategy Policy (DAFF 2007) are used as the basis for status determination.
Notes: B20 20 per cent of unfished biomass. BMSY Biomass at MSY. GVP Gross value of production. MSY Maximum sustainable yield. NER Net economic returns.

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21.1 Description of the fishery

Area fished

The Eastern Tuna and Billfish Fishery (ETBF) operates in the Exclusive Economic Zone, from Cape York to the Victoria – South Australia border, including waters around Tasmania and the high seas of the Pacific Ocean (Figure 21.1). Domestic management arrangements for the ETBF are consistent with Australia's commitments to the Western and Central Pacific Fisheries Commission (WCPFC; see Chapter 20).

Fishing methods and key species

Key species in the ETBF are shown in Table 21.1. Most of the catch in the fishery is taken with pelagic longlines, although a small quantity is taken using minor-line methods (Table 21.2). Some ETBF longliners catch southern bluefin tuna (Thunnus maccoyii)off New South Wales during winter, after fishing for tropical tunas and billfish earlier in the year, while others take them incidentally when targeting other tunas. All southern bluefin tuna taken must be covered by quota and landed in accordance with the Southern Bluefin Tuna Fishery Management Plan 1995. Recreational anglers and game fishers also target tuna and marlin in the ETBF. Many game fishers tag and release their catch, especially marlins. The retention of blue marlin (Makaira mazara)and black marlin (M. indica)has been banned in commercial fisheries since 1998, and catch limits have been introduced on longtail tuna (Thunnus tonggol),in recognition of the importance of these species to recreational anglers.

Management methods

The primary ETBF tuna and billfish species are managed through total allowable catches allocated as individual transferable quotas (ITQs). The Commonwealth Fisheries Harvest Strategy Policy (HSP; DAFF 2007) is not prescribed for fisheries managed under international agreements. However, a harvest strategy framework has been developed for the ETBF (Campbell 2012a). The framework has been used to set the total allowable commercial catch (TACC) for swordfish (Xiphias gladius)and striped marlin (Kajikia audax)since 2011, but is not currently used for tuna species.

Australia's catch in the ETBF as a percentage of the total catch from all nations in the Coral and Tasman seas has been declining across the major target species. This is due primarily to an increase in the catch by other nations for some species. The Tropical Tuna Resource Assessment Group (TTRAG) noted that the ETBF catch as a proportion of the total catch within the Coral and Tasman seas was relatively high for swordfish and striped marlin, and that the ETBF harvest strategy would therefore be effective. In 2013, TTRAG made some adjustments to the target reference catch rates used in the ETBF harvest strategy for swordfish and striped marlin. These provide better alignment with the HSP default reference points of 48 per cent of unfished biomass (B48) for the target and 20 per cent of unfished biomass (B20) for the limit.

In 2013, TTRAG found that the ETBF harvest strategy was not likely to achieve its objectives according to the requirements of the HSP for bigeye tuna (Thunnus obesus), yellowfin tuna (T.albacares)and albacore (T. alalunga). Australia's catch of these species was low in proportion to total regional catch, and, under these circumstances, changes to Australia's catch could not be expected to result in a change in the stock status (because of a lack of feedback to the stock as a whole).

The Australian Fisheries Management Authority (AFMA) Commission subsequently directed TTRAG to cease using the harvest strategy to calculate recommended biological commercial catch levels for bigeye tuna, yellowfin tuna and albacore, and to prepare information on stock status of tunas. In the absence of an accepted harvest strategy, and because there has been no allocation of tuna catches by the WCPFC, AFMA has applied TACCs based on historical catch levels in the fishery, and in accordance with any limits determined by the WCPFC or agreed through regional arrangements, such as the Tokelau Arrangement for the Management of the South Pacific Albacore Fishery.

The status of ETBF tuna and billfish is derived from the regional assessments undertaken for the WCPFC. Assessment results over the relevant geographic area modelled are used to determine stock status, but supplementary management advice may also be derived from the region most relevant to Australia. The WCPFC has agreed limit reference points for some stocks, but, in where agreed limit reference points are absent, status determination was informed by the proxies specified in the HSP.

From 1 July 2015, electronic monitoring has been mandatory for all full-time pelagic longline vessels in the ETBF and the Western Tuna and Billfish Fishery. At least 10 per cent of video footage of all hauls is reviewed to verify the accuracy of logbooks, which must be completed for 100 per cent of shots.

Fishing effort

The number of active vessels in the fishery (Figure 21.2) has decreased substantially in the past decade (from around 150 in 2002 to 37 in 2016), probably as a result of a decline in economic conditions in the fishery and the removal of vessels through the Securing our Fishing Future structural adjustment package in 2006–07 (Vieira et al. 2010).

FIGURE 21.2 Longline fishing effort, number of boat SFRs and active vessels in the ETBF, 1985 to 2016
Note: SFR Statutory fishing right.
Source: Australian Fisheries Management Authority

Catch

Following a decrease in effort, the total retained catch of all species in the ETBF declined from a high of more than 8,000 t in 2002 to around 4,200 t in 2013, but has since increased to above 6,000 t in 2016 (Figure 21.3). Swordfish and yellowfin tuna continue to be the main target species.

FIGURE 21.3 Total catch (from logbook data) for all methods, by species, in the ETBF, 1987 to 2016
Source: Australian Fisheries Management Authority
TABLE 21.2 Main features and statistics for the ETBF
Fishery statistics a201520152015201620162016
Stock TAC
(t)
Catch
(t)
Real value
(2014–15)
TAC
(t)
Catch
(t)
Real value
(2015–16)
Striped marlin351347$1.4 million351244$1.4 million
Swordfish1,3811,150$6.8 million1,3731,161$9.1 million
Albacore2,500949$2.0 million2,5001,101$3.9 million
Bigeye tuna1,056785$5.4 million1,056870$8.0 million
Yellowfin tuna2,2002,177$17.4 million2,2001,763$24.7 million
Total fishery 7,488 5,408 $33.0 million 7,480 5,139 $48.8 million

Fishery-level statistics20152016
EffortLongline: 8.22 million hooks
Minor line: na
Longline: 7.82 million hooks
Minor line: na
Fishing permitsLongline boat SFRs: 90
Minor line boat SFRs: 101
Longline boat SFRs: 86
Minor line boat SFRs: 93
Active vesselsLongline: 39
Minor line: 5
Longline: 37
Minor-line: 2
Observer coverageLongline: 5.87% b
Minor-line: zero
Longline: 8.7% b
Minor line: zero
Fishing methodsPelagic longline, minor line (trolling, rod and reel, handline)Pelagic longline, minor line (trolling, rod and reel, handline)
Primary landing portsCairns, Mooloolaba and Southport (Queensland); Bermagui, Coffs Harbour and Ulladulla (New South Wales)Cairns, Mooloolaba and Southport (Queensland); Bermagui, Coffs Harbour and Ulladulla (New South Wales)
Management methodsOutput controls: limited entry, gear restrictions
Input controls: TACC and ITQs
Output controls: limited entry, gear restrictions
Input controls: TACC and ITQs
Primary marketsDomestic: fresh
International: Japan, United States—mainly fresh; Europe—frozen; American Samoa, Thailand, Indonesia—albacore mainly for canning
Domestic: fresh
International: Japan, United States—mainly fresh; Europe—frozen; American Samoa, Thailand, Indonesia—albacore mainly for canning
Management plan Eastern Tuna and Billfish Fishery Management Plan 2010 Eastern Tuna and Billfish Fishery Management Plan 2010

a Fishery statistics are provided by calendar year to align with international reporting requirements. Real-value statistics are by financial year and are expressed in 2015–16 dollars. b Since 1 July 2015, e-monitoring is mandatory for all full-time pelagic longline vessels in the ETBF. At least 10% of video footage of all hauls is reviewed to verify the accuracy of logbooks, which must be completed for 100% of shots. The percentage of hooks observed is provided.
Notes: ITQ Individual transferable quota. na Not available. SFR Statutory fishing right. TACC Total allowable commercial catch.

21.2 Biological status

Striped marlin (Kajikia audax)

Striped marlin (Kajikia audax) 

Line drawing: FAO

Stock structure

Genetic studies have identified multiple stocks of striped marlin in the Pacific Ocean (for example, McDowell & Graves 2008; Purcell & Edmands 2011). As a result, the north Pacific Ocean and south-west Pacific Ocean (SWPO) stocks are assessed separately (WCPFC 2013). Information for the SWPO stock is reported here.

Catch history

Catch for the ETBF decreased slightly in 2016 to 244 t (Figure 21.4), while catch in the south Pacific decreased from 2,300 t in 2014 to 1,924 t in 2015 (Figure 21.5). An increase in south Pacific catch in 2011–12 was driven in part by increases in catch in the north that are not subject to the current conservation and management measure (CMM) for striped marlin—WCPFC CMM 2006-04—which only applies south of 15°S.

FIGURE 21.4 Striped marlin catch and TACC in the ETBF, 1984 to 2016
Note: TACC Total allowable commercial catch.
Source: Australian Fisheries Management Authority
FIGURE 21.5 Striped marlin catch in the south Pacific, 1970 to 2015
Source: Western and Central Pacific Fisheries Commission
Stock assessment

The last stock assessment for striped marlin in the SWPO was conducted in 2012 (Davies et al. 2012). Significant changes in the base case from the previous (2006) assessment included a 50 per cent reduction in Japanese longline catches over the entire model time period (because catches in the previous assessment were erroneously counted twice), faster growth rates, and the steepness of the stock–recruitment relationship being fixed at a higher level (0.8 rather than 0.55). A decreasing trend in recruitment through time was found, particularly from 1950 to 1970. There were conflicts among the standardised catch-per-unit-effort (CPUE) time series, and a series from the Japanese longline fishery was considered to be the most representative. Estimates of equilibrium maximum sustainable yield (MSY) and the associated reference points were highly sensitive to the assumed values of natural mortality and steepness in the stock–recruitment relationship. Estimates of stock status relative to MSY-based reference points, as used by the WCPFC, are therefore uncertain.

The base case in the assessment estimated that the latest (2010) spawning biomass had been reduced to 34 per cent of the levels predicted to occur in the absence of fishing (SBCURRENT/SBF=0 = 0.34 for the base case; range 0.32–0.44 across the base case and sensitivities). It was estimated that the spawning biomass was below the level associated with MSY (SBCURRENT/SBMSY = 0.87; range 0.67–1.14). Fishing mortality (2007 to 2010) was below FMSY (FCURRENT/FMSY = 0.81; range 0.51–1.21), and catches during this period were close to the estimated MSY (2,081 t; range 1,914–2,276 t). Annual catches over the most recent five years since the assessment (2011 to 2014) have averaged around 2,400 t, which exceeds the estimated MSY.

Stock status determination

The most recent estimate of the SWPO spawning biomass of striped marlin is above the WCPFC limit reference point of 20 per cent of the levels predicted to occur in the absence of fishing. The most recent base-case estimates of fishing mortality and most sensitivity analyses are below the level associated with MSY; however, recent catches are somewhat above the estimated MSY level. SWPO striped marlin is classified as not subject to overfishing and not overfished. The recent catch levels and the age of the stock assessment both contribute to increased uncertainty around the stock status of striped marlin in 2016. This trend is likely to affect future status determination. The Scientific Committee of the WCPFC recommended measures to control overall catch, through expansion of the geographical scope of CMM 2006-04 to cover the distribution of the stock; the WCPFC has not yet adopted this recommendation.

Swordfish (Xiphias gladius)

Swordfish (Xiphias gladius) 

Line drawing: Gavin Ryan

Stock structure

Although studies of swordfish have generally indicated a low level of genetic variation in the Pacific Ocean (Kasapidis et al. 2008), the WCPFC assesses two stocks separately: a north Pacific stock and an SWPO stock. The information reported here is for the SWPO stock.

Catch history

Swordfish catch in the ETBF increased slightly in 2016 (Figure 21.6). Catch in the south Pacific has generally been increasing since 2001, but decreased slightly in 2015 to 20,090 t (Figure 21.7).

FIGURE 21.6 Swordfish catch and TACC in the ETBF, 1984 to 2016
Note: TACC Total allowable commercial catch.
Source: Australian Fisheries Management Authority
FIGURE 21.7 Swordfish catch in the south Pacific, 1970 to 2015
Source: Western and Central Pacific Fisheries Commission
Stock assessment

The SWPO stock of swordfish was most recently assessed in 2013 (Davies et al. 2013) using the assessment package MULTIFAN-CL. This assessment builds on the 2008 assessment and is underpinned by several other analyses examining standardised CPUE series (for example, Campbell 2012b; Hoyle et al. 2013). The main uncertainty in the assessment pertains to swordfish growth, maturity and mortality-at-age schedules. Two schedules were used in the assessment: one derived from Hawaiian estimates and the other from Australian estimates. Although the schedule used affected the stock status of swordfish, the WCPFC Scientific Committee was unable to decide which schedule was more reliable (WCPFC 2013).

Model runs for both growth schedules indicated that the current (2007 to 2010) level of spawning biomass was above the level that would result in MSY (Australian estimate: SBCURRENT/SBMSY = 1.15–1.80; Hawaiian estimate: SBCURRENT/SBMSY = 1.86–2.54). The range of key model runs also indicated that current spawning biomass was above 20 per cent of the spawning biomass predicted to occur in the absence of fishing (SBCURRENT/SBF=0 = 0.26–0.60). However, estimates of fishing mortality relative to FMSY varied under the growth schedules, with the Hawaiian schedule indicating that overfishing was not occurring (FCURRENT/FMSY = 0.40–0.70) and the Australian schedule indicating that overfishing was occurring (FCURRENT/FMSY = 1.06–1.77).

Stock status determination

The most recent estimates of spawning biomass, from all models and sensitivities, are above the HSP default limit reference point of 20 per cent of the spawning biomass predicted to occur in the absence of fishing. As a result, the swordfish stock in the SWPO is classified as not overfished. However, the most recent estimates of fishing mortality relative to the FMSY reference point vary greatly, depending on the growth schedule assumed in the model. The WCPFC Scientific Committee was unable to decide which growth schedule was more reliable, and further research on growth schedules is underway to resolve this issue. The stock is classified as uncertain with regard to the level of fishing mortality.

Yellowfin tuna
AFMA

Albacore (Thunnus alalunga)

Albacore (Thunnus alalunga) 

Line drawing: FAO

Stock structure

Two distinct stocks of albacore (north Pacific and south Pacific) are found in the Pacific Ocean, generally associated with the two oceanic gyres. These two stocks are assessed separately (WCPFC 2015). Information for the south Pacific albacore stock is reported here.

Catch history

Catches in the ETBF increased to 1,101 t in 2016, the highest since 2009 (Figure 21.8). Catches in the south Pacific have increased in recent years, but decreased in 2015 to 68,306 t (Figure 21.9). The WCPFC Scientific Committee recommended that longline fishing mortality be reduced if the WCPFC's goal is to maintain economically viable catch rates.

FIGURE 21.8 Albacore catch and TACC in the ETBF, 1984 to 2016
Note: TACC Total allowable commercial catch.
Source: Australian Fisheries Management Authority
FIGURE 21.9 Albacore catch in the south Pacific, 1970 to 2015
Source: Western and Central Pacific Fisheries Commission
Stock assessment

The assessment for albacore in the south Pacific was updated in 2015 using MULTIFAN-CL (Harley et al. 2015). Substantial improvements in the 2015 stock assessment included improvements to the MULTIFAN-CL modelling framework, use of a regional disaggregated framework, use of operational data for construction of CPUE indices and regional weights, changes to some key biological parameters, inclusion of direct age-at-length data to improve growth estimation, and inclusion of additional tagging data (Harley et al. 2015). Two influential changes were a change in the natural mortality assumption (from 0.4 to 0.3 per year) and exclusion of the eastern Pacific from the assessment. Although the results of the assessment are broadly consistent with the 2012 assessment, the changes to the assessment combined with the additional years of fishing resulted in a more pessimistic picture, with substantially lower biomass and higher fishing mortality.

The base-case model in the assessment estimated that the latest (2013) spawning biomass was above the level associated with MSY (SBLATEST/SBMSY = 2.86; range 1.74–7.03) and above the adopted limit reference point (SBLATEST/SBF=0 = 0.40; range 0.30–0.60). It should be noted that the estimate of the biomass at MSY (BMSY) for south Pacific albacore is around 14 per cent of unfished levels, which is below the adopted limit reference point of 20 per cent—a target of BMSY would be inconsistent with the adopted limit reference point. Current (2009 to 2012 average) fishing mortality is below FMSY (FCURRENT/FMSY = 0.39; range 0.13–0.62), and recent catches are likely at, or slightly less than, estimates of MSY.

Stock status determination

The most recent estimate of spawning biomass is above the HSP default limit reference point of 20 per cent of initial unfished levels. The most recent estimates of fishing mortality are well below the levels associated with MSY, and recent catches are around MSY. As a result, albacore in the south Pacific Ocean is classified as not subject to overfishing and not overfished.

Bigeye tuna (Thunnus obesus)

Bigeye tuna (Thunnus obesus) 

Line drawing: FAO

Stock structure

Genetic data have indicated that bigeye tuna in the Pacific Ocean is a single biological stock (Grewe & Hampton 1998).

Catch history

Catches of bigeye tuna increased to 870 t in the ETBF in 2016, the highest levels since 2009 (Figure 21.10). Catches decreased in the WCPFC area in 2015 (Figure 21.11). Recent bigeye tuna catch in the WCPFC area (134,682 t in 2015) is well above the estimated MSY (108,520 t). Catch has been above this level since around 1987–88 (Figure 21.11).

FIGURE 21.10 Bigeye tuna catch and TACC in the ETBF, 1984 to 2016
Note: TACC Total allowable commercial catch.
Source: Australian Fisheries Management Authority
FIGURE 21.11 Bigeye tuna catch in the south Pacific, 1970 to 2015
Source: Western and Central Pacific Fisheries Commission
Stock assessment

The bigeye tuna stock in the western and central Pacific Ocean (WCPO) was most recently assessed in 2014 (Harley et al. 2014) using MULTIFAN-CL. The assessment was subject to significant changes and improvements following a review in 2012. It indicated that spawning biomass had declined to approximately half of initial levels by the mid 1970s and continued to decline after that. The base case in the assessment estimated that the 2012 spawning biomass had been reduced to 16 per cent of the levels predicted to occur in the absence of fishing (SBLATEST/SBF=0 = 0.16 for the base case; range 0.14–0.18 across the base case and three sensitivities). The 2012 spawning biomass was also below the level that will support MSY (SBLATEST/SBMSY = 0.77 for the base case; range 0.62–0.96). The assessment indicated that current (2008 to 2011 average) fishing mortality is 1.57 times the fishing mortality that will support MSY (FCURRENT/FMSY = 1.57 for the base case; range 1.27–1.95). Repeated runs of the assessment model resulted in inconsistencies in the parameter estimates, which were most likely due to conflicts in the input data (relating to growth, regional recruitment distributions and movement parameters). However, the stock status outcomes were consistent among model runs.

Stock status determination

The base case (and all sensitivities) in the latest assessment (Harley et al. 2014) indicates that bigeye tuna spawning biomass is below the 20 per cent depletion reference point adopted by the WCPFC (0.2SBF=0). This reference point corresponds with the limit reference point in the HSP. As a result, the stock is classified as overfished. The current fishing mortality across the WCPO is well in excess of levels needed to maintain MSY and has driven the stock to below the limit reference point (B20); consequently, the stock is classified as subject to overfishing. The WCPFC Scientific Committee has recommended a reduction of at least 36 per cent in fishing mortality from the average levels for 2008 to 2011, to reduce the fishing mortality rate to FMSY.

Yellowfin tuna (Thunnus albacares)

Yellowfin tuna (Thunnus albacares) 

Line drawing: FAO

Stock structure

Yellowfin tuna in the WCPO is currently considered to be a single biological stock (Langley et al. 2012). However, a recent study using newer genomic techniques provided strong evidence of genetically distinct populations of yellowfin tuna at three sites (Coral Sea, Tokelau and California) across the Pacific Ocean (Grewe et al. 2015). Further work is underway to confirm and expand on this initial study.

Catch history

Catch decreased in the ETBF in 2016 (Figure 21.12). In the wider WCPFC area, the 2015 catch was slightly lower than the 2014 catch, at 575,901 t (Figure 21.13), which is below the estimated MSY (586,400 t).

FIGURE 21.12 Yellowfin tuna catch and TACC in the ETBF, 1984 to 2016
Note: TACC Total allowable commercial catch.
Source: Australian Fisheries Management Authority
FIGURE 21.13 Yellowfin tuna catch in the south Pacific, 1970 to 2015
Source: Western and Central Pacific Fisheries Commission
Stock assessment

The yellowfin tuna stock in the WCPO was most recently assessed in 2014 (Davies et al. 2014) using MULTIFAN-CL, with data up to and including 2012. The base case in the assessment estimated that the 2012 spawning biomass had been reduced to 38 per cent of the levels predicted to occur in the absence of fishing (SBLATEST/SBF=0 = 0.38 for the base case; range 0.35–0.40 across the base case and three sensitivities). The 2012 spawning biomass was above the level that will support MSY (SBLATEST/SBMSY = 1.24 for the base case; range 1.05–1.51). The assessment indicated that current (2008 to 2011 average) fishing mortality is 0.72 times the fishing mortality that will support MSY (FCURRENT/FMSY = 0.72 for the base case; range 0.58–0.90).

Stock status determination

The results of the 2014 assessment indicate that the spawning biomass of yellowfin tuna is above the 20 per cent depletion reference point adopted by the WCPFC (0.2SBF=0). This reference point corresponds with the limit reference point in the HSP. As a result, the stock is classified as not overfished. The 2014 catch is slightly above the base-case MSY; however, the current fishing mortality for the base-case assessment is below that required to achieve MSY. As a result, the stock is classified as not subject to overfishing.

21.3 Economic status

Key economic trends

ABARES has conducted economic surveys of the ETBF since the early 1990s. The survey data are used to estimate the level of net economic returns (NER) earned in the fishery. The most recent survey results for the ETBF cover the 2011–12 and 2012–13 financial years. Non–survey based estimates for economic performance are available for 2013–14. Survey results show that NER were positive from 2010–11 to 2012–13; 2010–11 was the first year with positive NER since 2000–01 (Bath et al. 2016; Figure 21.14). This improvement was attributed to a reduced number of active vessels and lower associated costs. These changes followed the exit of vessels from the fishery in response to market forces and the Securing our Fishing Future structural adjustment package (Vieira et al. 2010), which removed 99 longline permits and 112 minor-line permits.

Between 2009–10 and 2010–11, improved economic performance in the fishery was driven primarily by a reduction in operating costs. In 2011–12, NER were estimated to have increased to $3.0 million. Revenue and operating costs were both estimated to have declined, with the fall in operating costs proportionately larger than the fall in revenue. The main drivers for the reduction in operating costs were falls in boat numbers, total effort, catch (which affects some key variable costs) and the estimated distance travelled by the ETBF fleet. From 2011–12 to 2012–13, NER remained positive but slightly lower as a result of higher fuel prices. Preliminary estimates for 2013–14 are that NER fell further to $0.1 million, a reduction mostly driven by higher operating costs and a relatively small increase in fishing income.

Previous improvements in the economic performance of the fishery are consistent with generally increasing productivity since the early 2000s (Stephan & Vieira 2013). Total factor productivity has followed a generally increasing trend since 1999–2000, although the rate of growth increased after 2001–02. The increased rate of growth occurred at the same time as the reduction in fleet size, driven primarily by market forces in the early 2000s and, later in that decade, by the Securing our Fishing Future structural adjustment package. This is likely to have left the more efficient vessels continuing to operate in the fishery, which may be the principal driver for the increasing productivity trend during the latter part of the decade.

Cost and NER estimates are not yet available for 2014–15 or 2015–16. Between 2014–15 and 2015–16, effort fell (from 8.22 million hooks to 7.82 million hooks), and the number of active vessels in the fishery fell from 39 to 37. Consistent with the decrease in effort, the total retained catch in the fishery decreased from 5,408 t to 5,139 t in 2015–16, indicating marginal improvements in productivity in terms of quantity of fish caught per hook deployed. Prices for all major species in the fishery increased significantly in 2015–16, leading to a strong increase in gross value of production despite falls in catch. The gross value of production increased in 2015–16 by 35 per cent (Figure 21.15). NER in 2015–16 are still uncertain; however, the available economic information indicates that NER in the fishery increased in 2015–16.

FIGURE 21.14 NER for the ETBF, 2003–04 to 2013–14
Note: NER Net economic returns. Data for 2013–14 are preliminary.
Source: Bath et al. 2016
FIGURE 21.15 Real GVP for the ETBF, 2005–06 to 2015–16
Note: GVP Gross value of production.

Management arrangements

Despite being a managed fishery, the ETBF has previously exhibited some of the economic characteristics of an unmanaged, open-access fishery (Kompas et al. 2009). Estimates suggest that the fishery earned negative NER between 2000–01 and 2009–10. Low NER are likely to have been a major reason for a large proportion of the fishery's permits being inactive. This is a sign that the fishery was overcapitalised. The structural adjustment under the Securing our Fishing Future package addressed these issues to a degree—it left fewer vessels sharing a similar amount of catch and revenue.

In March 2011, output controls were introduced for five key target species in the form of TACCs, allocated as ITQs. The removal of some input controls under ITQs can provide fishers with more flexibility to fish with a more efficient combination of inputs (Elliston & Cao 2004). The transferability of statutory fishing rights among fishers also allows more efficient allocation of these rights. This is likely to result in the catch being taken by the most efficient operators in the fishery.

The setting of TACCs in the ETBF is complicated by uncertainty around what level of TACC is consistent with maximising NER from an internationally shared stock (see ‘Performance against economic objective'). If TACCs are set too high so that they do not constrain a species' catch, the incentive for quota trade and the associated positive impacts for fishery-level efficiency are reduced (Elliston et al. 2004). If TACCs are set too low (based on a stock's biological and economic status), some level of NER will be foregone.

Performance against economic objective

International sharing of stocks complicates both the selection of economic-based targets and the assessment of economic status against the objective of maximum economic yield (MEY), intended to maximise NER to the Australian community. Stock assessment is particularly complicated for the ETBF because the catch may be a relatively small proportion of the total WCPFC catch, and the degree of connectivity between the Australian population and that in the wider region remains uncertain for some species. For some internationally shared stocks, a reduction in the Australian catch may not necessarily lead to response in stock abundance and, therefore, profitability in the long term. For two stocks in the ETBF—swordfish and striped marlin—Australia's share of the catch is considered to be high enough for domestic action to have a more direct influence on stock abundance. These two stocks are managed under a harvest strategy designed to achieve a catch rate target biomass for prime-size fish consistent with the HSP economic target proxy of 48 per cent of unfished levels. Recent implementation of the harvest strategy indicates that since 2008 swordfish stock levels have been close to, but just below, the target reference point (Campbell 2016). For striped marlin, catch rates have been between the target and limit reference points for more than a decade, but have approached the target since 2013 (Campbell 2016). As a result, these two species have increased their contribution to overall NER from the fishery. The potential lack of association between domestic management actions and changes in stock biomass for the tuna species in the ETBF means that stock-wide BMEY may not be relevant.

The species-specific biomass targets in this fishery are based on the expected catch rates and the size proportion that is expected to occur when the level of mean spawners per recruit is at 48 per cent of initial unfished levels. This is assumed to be consistent with the MEY target recommended by the HSP. It is unclear how accurately the target reflects MEY. Since the harvest strategy for the fishery was implemented in 2010, NER have been positive. However, it is unclear to what extent the targets are responsible for this. NER were improving in the fishery before the harvest strategy was implemented, and many factors other than the harvest strategy may have influenced the fishery's economic performance.

21.4 Environmental status

Product from the ETBF currently has export approval under inclusion on the List of Exempt Native Specimens under the Environment Protection and Biodiversity Conservation Act 1999 until 22 August 2019. Conditions under this approval, in addition to standard conditions of reporting and monitoring, include updating the ecological risk assessment for the ETBF, developing and implementing a framework for the management of non-quota and bycatch species, and continuing to determine the impact of fishing in the ETBF on shark species.

Under the level 3 Sustainability Assessment for Fishing Effects (for fish only), two species of sunfish and three species of shark were identified as being at high risk from the effects of fishing in the ETBF (Zhou et al. 2007). A 2012 review of the ecological risk assessment, using new information on sunfish, has reclassified both sunfish species as medium risk. The priorities of the ecological risk management response are to reduce interactions with marine turtles, seabirds and whales because of their protected status (AFMA 2012), and to reduce the capture and mortality of sharks by implementing the 20-shark trip limit. The ecological risk management report also lists specific actions for the priority groups—for example, all vessels in the ETBF are required to carry line cutters and de-hookers so that sharks, turtles and other protected species can be easily removed from fishing gear, should they become hooked or entangled. Results from a new ecological risk assessment in the ETBF in 2017 will be reported in Fishery status reports 2018.

The introduction of electronic monitoring in the ETBF from mid 2015 has improved the accuracy of logbooks, particularly in the reporting of discarded or released catch. This improved reporting may be reflected in apparent higher levels of interaction for 2016, reported below.

In 2016, logbooks indicated that 2,005 shortfin mako sharks (Isurus oxyrinchus)were hooked in the ETBF. Of these, 744 were dead and 1,261 were released in unknown condition. Eight longfin mako sharks (I.paucus)were also hooked; two were dead and six were in unknown condition. Nine porbeagle sharks (Lamna nasus)were hooked and released, with eight in unknown condition. Forty-one silky sharks (Carcharhinus falciformis) were hooked and released in unknown condition. Thirty-nine green turtles (Chelonia mydas)were hooked; 30 were released alive and 9 were dead. Thirty-two leatherback turtles (Dermochelys coriacea) and nine loggerhead turtles (Carettacaretta)were also hooked; all were released alive except for three loggerheads that were dead. Two hawksbill turtles (Eretmochelys imbricate) were hooked, with one dead and one released alive; and one flatback turtle (Natator depressus) was caught and was dead. Seventeen unidentified turtles were hooked, with 12 alive and 5 dead.

Five black-browed albatrosses (Thalassarche melanophris)were caught, with one released alive and four dead, and one wandering albatross (Diomedea exulans) was released alive. Twenty unidentified albatrosses were hooked, with 4 released alive and 16 dead. Two flesh-footed shearwaters (Ardenna carneipes) and four unidentified shearwaters were hooked, with all being dead except one flesh-footed shearwater. One Australian gannett (Morus serrator) was released alive, and one unidentified bird was dead.

Several interactions with marine mammals were also recorded; these comprised three unidentified dolphins (released alive), one unidentified whale (released alive), two toothed whales (Parvorder Odontoceti; released alive), five short-finned pilot whales (Globicephala macrorhynchus; released alive), one long-finned pilot whale (G. melas; released alive), one unidentified seal (released alive) and one Australian fur seal (Arctocephalus pusillus; released alive).

21.5 References

AFMA 2012, Ecological risk management: report for the Eastern Tuna and Billfish Fishery, Australian Fisheries Management Authority, Canberra.

Bath, A, Skirtun, M & Green, R 2016, Australian fisheries economic indicators report 2014:financial and economic performance of the Eastern Tuna and Billfish Fishery, ABARES, Canberra.

Campbell, R 2012a, ‘Implementation of the ETBF harvest strategy and calculation of the recommended biological commercial catches for 2013/14', working paper presented to the fifth meeting of the Tropical Tuna Resource Assessment Group, Canberra, 4–5 September 2012.

—— 2012b, ‘Abundance indices for striped marlin and broadbill swordfish in the south-west Pacific based on standardised CPUE from the Australian longline fleet', information paper WCPFC-SC8-SA-IP-13, Western and Central Pacific Fisheries Commission Scientific Committee eighth regular session, Busan, Republic of Korea, 7–15 August 2012.

—— 2016, ‘Implementation of the ETBF harvest strategy and calculation of recommended biological commercial catches for broadbill swordfish and striped marlin for the 2017/18 quota year', information paper to the 16th meeting of the Tropical Tuna Resource Assessment Group, Mooloolaba, 18–19 October 2016.

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

Davies, N, Hoyle, S & Hampton, J 2012, ‘Stock assessment of striped marlin (Kajikia audax) in the southwest Pacific Ocean', working paper WCPFC-SC8-2012/SA-WP-05, WCPFC Scientific Committee eighth regular session, Busan, Republic of Korea, 7–15 August 2012.

——, Pilling, G, Harley, S & Hampton, J 2013, ‘Stock assessment of swordfish (Xiphias gladius) in the southwest Pacific Ocean', unpublished report to the WCPFC Scientific Committee, WCPFC-SC9-2013/SA-WP-05.

——, Harley, S, Hampton, J & McKechnie, S 2014, ‘Stock assessment of yellowfin tuna in the western and central Pacific Ocean', unpublished report to the WCPFC Scientific Committee, WCPFC-SC0-2014/SA-WP-04.

Elliston, L & Cao, L 2004, Managing effort creep in Australian fisheries: an economic perspective, Australian Bureau of Agricultural and Resource Economics eReport 04.5, prepared for the Fisheries Resources Research Fund, Canberra.

——, Newton, P, Galeano, D, Gooday, P, Kompas, T & Newby, J 2004, Economic efficiency in the South East Trawl Fishery, ABARE report prepared for the Fisheries Resources Research Fund, Canberra.

Grewe, PM & Hampton, J 1998, ‘An assessment of bigeye (Thunnus obesus) population structure in the Pacific Ocean based on mitochondrial DNA and DNA microsatellite analysis', SOEST 98-05, JIMAR Contribution 98-320, Joint Institute for Marine and Atmospheric Research, University of Hawaii, Honolulu.

——, Feutry, P, Hill, PL, Gunasekera, RM, Schaefer, KM, Itano, DG, Fuller, DW, Foster, SD & Davies, CR 2015, ‘Evidence of discrete yellowfin tuna (Thunnus albacares) populations demands rethink of management for this globally important resource', Scientific Reports, vol. 5, doi 10.1038/srep16916.

Harley, S, Davies, N, Hampton, J & McKechnie, S 2014, ‘Stock assessment of bigeye tuna in the western and central Pacific Ocean', working paper WCPFC-SC10-2014/SA-WP-01, WCPFC Scientific Committee 10th regular session, Republic of the Marshall Islands, 6–14 August 2014.

——, Davies, N, Tremblay-Boyer, L, Hampton, J & McKechnie, S 2015, ‘Stock assessment for south Pacific albacore tuna', working paper WCPFC-SC11-2015/SA-WP-06, WCPFC Scientific Committee 11th regular session, Pohnpei, Federated States of Micronesia, 5–13 August 2015.

Hoyle, S, Davies, N & Chang, E 2013, ‘CPUE standardisation for swordfish in the southwestern Pacific Ocean', information paper WCPFC-SC9/SA-IP-03, WCPFC Scientific Committee ninth regular session, Pohnpei, Federated States of Micronesia, 6–14 August 2013.

Kasapidis, P, Magoulas, A, Gacía-Cortés, B & Mejuto, J 2008, ‘Stock structure of swordfish (Xiphias gladius) in the Pacific Ocean using microsatellite DNA markers', working paper WCPFC-SC4-2008/BI-WP-04, WCPFC Committee fourth regular session, Port Moresby, Papua New Guinea, 11–22 August 2008.

Kompas, T, Che, N & Gooday, P 2009, Analysis of productivity and the impacts of swordfish depletion in the Eastern Tuna and Billfish Fishery, ABARE research report 09.4, ABARE, Canberra.

Langley, A, Herrera, M & Million, J 2012, ‘Stock assessment of yellowfin tuna in the Indian Ocean using MULTIFAN-CL', paper IOTC-2012-WTT14-38_Rev 1, IOTC, presented at the 14th session of the Indian Ocean Tuna Commission Working Party on Tropical Tunas, Mauritius, 24–29 October 2012.

McDowell, JR & Graves, JE 2008, ‘Population structure of striped marlin (Kajikia audax) in the Pacific Ocean based on analysis of microsatellite and mitochondrial DNA', Canadian Journal of Fisheries and Aquatic Sciences, vol. 68, pp. 1307–20.

Purcell, CM & Edmands, S 2011, ‘Resolving the genetic structure of striped marlin, Kajikia audax,in the Pacific Ocean through spatial and temporal sampling of adult and immature fish', Canadian Journal of Fisheries and Aquatic Sciences, vol. 65, pp. 1861–75.

Stephan, M & Vieira, S 2013, Trends in total factor productivity of five key Commonwealth managed fisheries,ABARES report 13.09, ABARES, Canberra.

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

WCPFC 2013, Commission for the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean: Scientific Committee ninth regular session—summary report, Pohnpei, Federated States of Micronesia, 6–14 August 2013, WCPFC, Pohnpei.

—— 2015, Commission for the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean: Scientific Committee 11th regular session—summary report, Pohnpei, Federated States of Micronesia, 5–13 August 2015, WCPFC, Pohnpei.

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

Radio beacons
AFMA

Chapter 22: Skipjack Tuna Fishery

H Patterson and A Bath

FIGURE 22.1 Area fished in the Skipjack Tuna Fishery, 2005–06 to 2015–16
Note: The last effort in the fishery occurred in 2008–09.
TABLE 22.1 Status of the Skipjack Tuna Fishery
Status
Biological status
a, b
2015
Fishing mortality
2015
Biomass
2016
Fishing mortality
2016
Biomass
Comments
Indian Ocean skipjack tuna (Katsuwonus pelamis)Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedNo Australian vessels fished in 2016. Current estimates of catch in the Indian Ocean are less than MSY. Spawning biomass is above the limit reference point.
Western and central Pacific Ocean skipjack tuna (Katsuwonus pelamis)Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedNo Australian vessels fished in 2016. Current estimates of fishing mortality in the WCPO are below FMSY. Spawning biomass is above the limit reference point.

Economic status
No Australian vessels fished in 2015 or 2016. Fishing is opportunistic and highly dependent on availability and the domestic cannery market. Currently, no domestic cannery has active contracts for skipjack tuna.

a Ocean-wide assessments and the default limit reference points from the Indian Ocean Tuna Commission are used as the basis for determining the status of Indian Ocean skipjack tuna. b Ocean-wide assessments and the limit reference point from the Western and Central Pacific Fisheries Commission are used as the basis for determining the status of Pacific Ocean skipjack tuna.
Notes: FMSY Fishing mortality at maximum sustainable yield. MSY Maximum sustainable yield. WCPO Western and central Pacific Ocean.

[expand all]

22.1 Description of the fishery

Area fished

Two stocks of skipjack tuna (Katsuwonus pelamis) are thought to exist in Australian waters: one on the east coast and one on the west coast. The two stocks are targeted by separate fisheries: the Eastern Skipjack Tuna Fishery (ESTF) and the Western Skipjack Tuna Fishery (WSTF). These are collectively termed the Skipjack Tuna Fishery (STF), but the two stocks are assessed separately. The ESTF and the WSTF extend through the same area as the Eastern Tuna and Billfish Fishery (ETBF; Chapter 21), and the Western Tuna and Billfish Fishery (WTBF; Chapter 24), respectively, with the exception of an area of the ETBF off northern Queensland (Figure 22.1). Australian waters are at the edge of the species' range, with centres of abundance in the equatorial waters of the Indian and Pacific oceans. Availability of skipjack tuna in both the ESTF and the WSTF is highly variable. The Indian Ocean stock of skipjack tuna is managed under the jurisdiction of the Indian Ocean Tuna Commission (IOTC), whereas the stock found in the western and central Pacific Ocean (WCPO) is managed under the jurisdiction of the Western and Central Pacific Fisheries Commission (WCPFC).

Fishing methods and key species

Historically, the majority of fishing effort has used purse-seine gear (about 98 per cent of the catch). A small amount of pole-and-line effort (when poling is used on its own) is managed as a minor-line component of the ETBF and the WTBF.

Management methods

The skipjack tuna harvest strategy consists of a series of catch-level triggers that invoke control rules (AFMA 2008). The control rules initiate closer monitoring of the ESTF and the WSTF, semi-quantitative assessments and revision of trigger levels. The catch triggers are set at different levels for the ESTF and the WSTF, based on historical catch of skipjack tuna in the domestic fisheries and regional assessments of stock status. Management action is only initiated when there is clear evidence of a significant increase in catches. Target and limit reference points are not defined in the Australian skipjack harvest strategy, but have been defined in both the IOTC (on an interim basis) and the WCPFC. These reference points are consistent with those prescribed by the Commonwealth Fisheries Harvest Strategy Policy (HSP; DAFF 2007). The decision rules in the Australian harvest strategy for skipjack are not sufficient to restrict effort in a short time frame, if required, because they simply call for monitoring and revision of trigger levels. This would add a substantial time lag to any response. Catches of yellowfin tuna (Thunnus albacares)and bigeye tuna (T. obesus),which are often caught incidentally in purse-seine fisheries targeting skipjack, are limited by trip and season limits.

Fishing effort

There has been no fishing effort in the STF since the 2008–09 fishing season. Variability in the availability of skipjack tuna in the Australian Fishing Zone and the prices received for product influence participation levels in the fishery.

Catch

Globally, catch of skipjack tuna has increased steadily since the 1970s, and skipjack tuna has become one of the most commercially important tuna species in both the Indian and Pacific oceans. Catch in the STF increased for a short period from 2005 to 2008, peaking at 885 t in 2007–08. The catch was supplied almost exclusively to the cannery in Port Lincoln. However, the cannery closed in 2010, and there has been no catch in the STF since the 2008–09 fishing season.

TABLE 22.2 Main features and statistics for the STF
Fishery statistics a2014–15
fishing season
2014–15
fishing season
2014–15
fishing season
2015–16
fishing season
2015–16
fishing season
2015–16
fishing season
Fishery TAC
(t)
Catch
(t)
Real value
(2014–15)
TAC
(t)
Catch
(t)
Real value
(2015–16)
ESTF0$00$0
WSTF0$00$0
Total fishery 0 $0 0 $0

Fishery-level statistics2014-15 fishing season2015-16 fishing season
Effort00
Fishing permitsESTF: 18; WSTF: 14ESTF: 17; WSTF: 14
Active vessels00
Observer coverageESTF purse seine: 0
WSTF purse seine: 0
ESTF purse seine: 0
WSTF purse seine: 0
Fishing methodsPurse seine (predominant), pole-and-line methods (when poling is used on its own, it is managed as a minor-line component of the ETBF and the WTBF)Purse seine (predominant), pole-and-line methods (when poling is used on its own, it is managed as a minor-line component of the ETBF and the WTBF)
Primary landing portsNone; previously Port Lincoln (South Australia) cannery, which closed in May 2010None; previously Port Lincoln (South Australia) cannery, which closed in May 2010
Management methodsInput controls: limited entry, gear (net size), area controls, transhipment controls
Output controls: bycatch limits
Input controls: limited entry, gear (net size), area controls, transhipment controls
Output controls: bycatch limits
Primary marketsDomestic and international: currently noneDomestic and international: currently none
Management plan Skipjack Tuna Fishery management arrangements 2009(AFMA 2009) Skipjack Tuna Fishery management arrangements 2009(AFMA 2009)

a Fishery statistics are provided by fishing season, unless otherwise indicated. Fishing season is 1 July to 30 June. Real-value statistics are provided by financial year.
Notes: ESTF Eastern Skipjack Tuna Fishery. ETBF Eastern Tuna and Billfish Fishery. TAC Total allowable catch. WSTF Western Skipjack Tuna Fishery. WTBF Western Tuna and Billfish Fishery. – Not applicable.

Unloading skipjack tuna
Kevin McLoughlin, ABARES

22.2 Biological status

Indian Ocean skipjack tuna (Katsuwonus pelamis)

Indian Ocean skipjack tuna (Katsuwonus pelamis) 

Line drawing: FAO

Stock structure

Skipjack tuna in the Indian Ocean is considered to be a single stock for stock assessment purposes. Tagging studies have shown large movements of skipjack tuna in the Indian Ocean and support the assumption of a single biological stock (IOTC 2014).

Catch history

Total catch of skipjack tuna in the Indian Ocean increased slowly from the 1950s, reaching around 50,000 t in the 1970s. With the expansion of the purse-seine fleet in the early 1980s, catch increased rapidly to a peak of 610,000 t in 2006. Since the peak, purse-seine catch has declined, particularly in the areas off Somalia, Kenya and Tanzania, and around the Maldives. A similar decline in the catch taken by Maldivian pole-and-line vessels has also occurred. These reduced catches may be partially explained by drops in effort related to the effects of piracy in the western Indian Ocean. Total catch in the IOTC area decreased from 421,408 t in 2014 to 393,947 t in 2015 (Figure 22.2).

Historically, effort in the WSTF has been low. Catch has been reported in just three fishing seasons in the past 10 years. In 2005–06, catch was 446 t, before nearly doubling to 847 t in 2006–07 and 885 t in 2007–08. There has been no fishing in the WSTF since 2008–09.

FIGURE 22.2 Skipjack tuna catch in the IOTC area, 1970 to 2015
Note: IOTC Indian Ocean Tuna Commission.
Source: IOTC
Stock assessment

The Indian Ocean skipjack tuna stock assessment was updated in 2014 using two methods: Stock Synthesis 3 (SS3) and a catch-based method. The SS3 assessment was used for advice on stock status, and updates the 2011 and 2012 assessments of this stock using revised input parameters and catch-per-unit-effort (CPUE) indices. However, considerable uncertainty remains in the assessment, including uncertainty in the annual catch levels, particularly for artisanal fisheries where the level of reporting is generally poor. In addition, recent declines in catch and CPUE in pole-and-line and purse-seine fisheries are not fully understood, and are therefore of some concern (IOTC 2014). Noting these uncertainties, the updated assessment indicated that the current (2013) spawning biomass (SB) was relatively high—above the level needed to achieve maximum sustainable yield (MSY; SB2013/SBMSY = 1.59; range 1.13–2.14) and 58 per cent of the initial unfished biomass (SB2013/SB0 = 0.58; range 0.53–0.62) (IOTC 2014). Given the difficulty in estimating fishing mortality from the model, a proxy for fishing mortality (catch; C) was used and was estimated to be below the level that would support MSY (C2013/CMSY = 0.62; range 0.49–0.75). The catch in the IOTC area in 2015 (393,947 t) was below the estimated level of MSY (684,000 t; range 550,000–849,000 t; Figure 22.2), and just below the five-year average of 394,298 t.

Stock status determination

Despite the uncertainties in the assessment noted above, the results of the current assessment indicate that the spawning biomass is well above the HSP limit reference point of 20 per cent of initial unfished biomass. As a result, the stock is classified as not overfished. The current level of the fishing mortality proxy is also below that required to achieve MSY, so the stock is classified as not subject to overfishing.

Western and central Pacific Ocean skipjack tuna (Katsuwonus pelamis)

Stock structure

Skipjack tuna in the WCPO is considered to be a single stock for stock assessment purposes (Rice et al. 2014).

Catch history

Catch of skipjack tuna in the WCPO increased steadily throughout the 1980s as a result of growth in the international purse-seine fleet, before stabilising at around 1,000,000 t in the 1990s. Rapid increases in catch in the western equatorial zone have resulted in catches exceeding 1,500,000 t for each of the past 10 years (Figure 22.3).

Historically, effort in the ESTF has been very low. Catch has only been registered once in the past 10 years, with 44 t caught in 2005–06.

FIGURE 22.3 Skipjack tuna catch in the WCPFC area, 1970 to 2015
Note: WCPFC Western and Central Pacific Fisheries Commission
Source: WCPFC
Stock assessment

The skipjack tuna stock assessment for the WCPO was updated in 2016 using MULTIFAN-CL software (McKechnie et al. 2016) and incorporated three additional years of data, including a period of El Niño conditions, and the recommendations of the previous assessment (Rice et al. 2014). The outcome of the updated assessment is largely similar to that of the previous assessment. The base case in the assessment estimated that the latest (2015) spawning biomass was 58 per cent of the level predicted to occur in the absence of fishing (SBlatest/SBF=0 = 0.58; range 0.39–0.68 across the base case and sensitivities) and well above the adopted limit reference point of 0.2 SBF=0. Current fishing mortality (2011 to 2014 average) was estimated to be below the fishing mortality that will support MSY (Fcurrent/FMSY = 0.45; range 0.38–0.64 across the base case and sensitivities). In 2015, the catch in the WCPFC area was 1,831,440 t; this is below the updated estimate of MSY (1,891,000 t; Figure 22.3). The 2015 catch was above the five-year average of 1,791,788 t.

Stock status determination

The results of the assessment indicate that the spawning biomass is relatively high and above the WCPFC limit reference point of 20 per cent of the spawning biomass predicted to occur in the absence of fishing. As a result, the stock is classified as not overfished. The current level of fishing mortality is also below the level required to achieve MSY, so the stock is classified as not subject to overfishing.

22.3 Economic status

Key economic trends

Vessels have not been active in the STF since the 2008–09 fishing season; therefore, no net economic returns (NER) have been generated. Few vessels have fished in either the ESTF or the WSTF since 2003–04, suggesting that there is little economic incentive to fish and therefore low NER during this period.

Opportunistic fishing was previously prominent in the STF, since the stock availability in Australian waters is highly variable from year to year. Historically, effort has largely depended on both fish availability and the existence of a domestic tuna canning market. Currently, there is no domestic cannery with active contracts for skipjack tuna.

Management arrangements

The harvest strategy in place for the fishery is based on catch-level triggers that initiate management action and close monitoring of the fishery once catches exceed a certain level. Currently, 17 permits are issued in the ESTF and 14 in the WSTF. These are held by 15 companies, 7 of which hold one or more permits for both fisheries (AFMA 2016, 2017). This implies that, if operational and market conditions were to change dramatically, fishing effort could be activated. It is unlikely that an increase in effort in the Australian skipjack fisheries in the short term would negatively affect stocks and future NER flows, because the Australian catch is likely to be a relatively small proportion of the global skipjack tuna catch.

Performance against economic objective

The harvest of stocks that are internationally shared complicates both the selection of economic-based targets and the assessment of economic status against maximum economic yield (MEY). Assessment is particularly complicated where the Australian catch is a relatively small proportion of the total international catch. For the STF, reductions in any Australian catch in the fishery may not necessarily lead to an increase in stock and, therefore, profitability in the long term. Consequently, a BMEY target for the STF alone is not appropriate. Given these characteristics and the low levels of activity in the fishery in recent years (no catch since the 2008–09 fishing season), continuation of the low-cost management approach currently applied in the fishery is appropriate.

22.4 Environmental status

In 2016, the STF received a 10-year exemption from export provisions (until 9 October 2026) and was accredited under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). Approval is on the condition that the Australian Fisheries Management Authority reviews its management regime within 12 months of a level 2a trigger being reached.

The STF had previously undergone the ecological risk assessment (ERA) process up to level 3. Based on this assessment, which considered finfish and chondrichthyans, no species was considered to be at high risk because of the low fishing effort in the fishery (Zhou et al. 2009). However, 25 species of marine mammals were identified as high risk in the level 2 ERA process (Daley et al. 2007). Mammals were not considered in the level 3 assessment. The ecological risk management report for the fishery is therefore designed to achieve adequate monitoring to establish the level of interaction that may occur if effort increases, and to quantify the effect of the fishery on the marine mammal species identified as being at high risk (AFMA 2010).

To date, no interactions have been recorded of skipjack tuna purse-seine nets with species protected under the EPBC Act, such as marine mammals or turtles.

22.5 References

AFMA 2008, Skipjack tuna harvest strategy, Australian Fisheries Management Authority, Canberra.

—— 2009, Skipjack Tuna Fishery management arrangements 2009, AFMA, Canberra.

—— 2010, Ecological risk management report for the Skipjack Tuna Fishery, AFMA, Canberra.

—— 2016, Western Skipjack Fishery permit holders—3 November 2016, Excel spreadsheet, AFMA, Canberra.

—— 2017, Eastern Skipjack Fishery permit holders—9 February 2017, Excel spreadsheet, AFMA, Canberra.

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

Daley, R, Dowdney, J, Bulman, C, Sporcic, M, Fuller, M, Ling, S & Hobday, A 2007, Ecological risk assessment (ERA) for effects of fishing: Skipjack Tuna Fishery, report to AFMA, Canberra.

IOTC 2014, Report of the sixteenth session of the Scientific Committee, Seychelles, 8–12 December 2014, IOTC-2014-SC17-R[E], Indian Ocean Tuna Commission, Victoria, Seychelles.

McKechnie, S, Hampton, J, Pilling, GM & Davies, N 2016, ‘Stock assessment of skipjack tuna in the western and central Pacific Ocean', working paper WCPFC-SC12-2016/SA-WP-04, WCPFC Scientific Committee 12th regular session, Bali, Indonesia, 3–11 August 2016.

Rice, J, Harley, S, Davies, N & Hampton, J 2014, ‘Stock assessment of skipjack tuna in the western and central Pacific Ocean', working paper WCPFC-SC10-2014/SA-WP-05, WCPFC Scientific Committee 10th regular session, Republic of the Marshall Islands, 6–14 August 2014.

Zhou, S, Fuller, M & Smith, T 2009, Rapid quantitative risk assessment for fish species in seven Commonwealth fisheries, report to AFMA, Canberra.

Chapter 23: Southern Bluefin Tuna Fishery

H Patterson, S Nicol and R Curtotti

FIGURE 23.1 Purse-seine effort and longline catch in the Southern Bluefin Tuna Fishery, 2016
Note: SBT Southern Bluefin Tuna.
TABLE 23.1 Status of the Southern Bluefin Tuna Fishery
Status
Biological status
2015
Fishing mortality
2015
Biomass
2016
Fishing mortality
2016
Biomass
Comments a
Southern bluefin tuna (Thunnus maccoyii)UncertainOverfishedUncertainOverfishedThe estimate of spawning biomass is well below 20% of unfished biomass. The global TAC, set in line with the management procedure, should allow rebuilding. Significant uncertainty remains around unaccounted catch, which, if occurring, would reduce the probability of the stock rebuilding.

Economic status
NER are expected to have remained positive. The overfished status of the stock poses a risk to future NER. Economic status will improve as the stock is rebuilt under the management procedure.

a The global assessment of southern bluefin tuna and the default limit reference point from the Commonwealth Fisheries Harvest Strategy Policy (DAFF 2007) are used as the basis for status determination.
Notes: NER Net economic returns. TAC Total allowable catch.

Southern bluefin tuna
Matt Daniel, AFMA

[expand all]

23.1 Description of the fishery

Area fished

The Southern Bluefin Tuna Fishery (SBTF) spans the Australian Fishing Zone. Southern bluefin tuna (Thunnus maccoyii) is targeted by fishing fleets from a number of nations, both on the high seas and within the Exclusive Economic Zones (EEZs) of Australia, New Zealand, Indonesia and South Africa. Young fish (1–4 years) move from the spawning ground in the north-east Indian Ocean into the Australian EEZ and southwards along the Western Australian coast (Figure 23.1). Surface-schooling juveniles are found seasonally in the continental-shelf region of southern Australia. Current evidence suggests that juveniles return to the Great Australian Bight in the austral summer, but there is some uncertainty about the proportion that returns (Basson et al. 2012). The majority of the Australian catch is taken in the Great Australian Bight, with smaller amounts taken from the longline fisheries, mainly off south-eastern Australia.

Fishing methods

Since 1992, most of the Australian catch has been taken by purse seine, targeting juvenile southern bluefin tuna (2–5 years) in the Great Australian Bight. This catch is transferred to aquaculture farming operations off the coast of Port Lincoln in South Australia, where the fish are grown to a larger size to achieve higher market prices. Australian domestic longliners operating along the east coast catch some southern bluefin tuna, and recreational fishing for the species has increased in recent years. Throughout the rest of its range, southern bluefin tuna is targeted by pelagic longliners from other fishing nations.

Management methods

The Commonwealth Fisheries Harvest Strategy Policy (DAFF 2007) is not prescribed for fisheries managed jointly under international management arrangements, such as the SBTF, which is managed under the 1994 Convention for the Conservation of Southern Bluefin Tuna. In 2011, the Commission for the Conservation of Southern Bluefin Tuna (CCSBT) adopted a management procedure (the Bali Procedure), which is analogous to a harvest strategy, and this has been used to set the global total allowable catch (TAC) since 2012. The management procedure aims to achieve rebuilding of the southern bluefin tuna stock to 20 per cent of its initial unfished biomass (the interim rebuilding target) by 2035, with 70 per cent probability. The global TAC is allocated to members and cooperating non-members as agreed by the CCSBT under the 2011 CCSBT Resolution on the Allocation of the Global Total Allowable Catch. The Australian Fisheries Management Authority (AFMA) sets the TAC for the SBTF in accordance with Australia's allocation.

The Commission has noted that levels of unaccounted mortality may be substantial in the global fishery. A high level of unaccounted mortality may constitute exceptional circumstances because it was not taken into consideration when the management procedure was developed. The Commission has agreed to a definition of attributable mortality, and members have agreed to manage all sources of mortality within their national allocations. The Commission is also working to better account for non-member catch.

Fishing effort

Most of the Australian catch and effort is by purse-seine vessels in the Great Australian Bight and waters off South Australia. The number of vessels in the purse-seine fishery has been relatively stable, ranging from five to eight since the 1994–95 fishing season. In 2009, and 2011 to 2016, the catch was taken more to the east of the Bight, closer to Port Lincoln, resulting in shorter towing distances to bring the fish to the aquaculture grow-out cages.

The number of longline vessels fishing for southern bluefin tuna off the east coast has been more variable over time. Effort in the longline sector is largely dependent on available quota.

Catch

The reported global catch of southern bluefin tuna has declined since the peak catches in the early 1960s, but has been relatively stable since the mid 2000s. The Australian catch and TAC were stable from 1990 to 2009 and were then reduced as part of a global reduction in catch. Since adoption of the management procedure, the global TAC has increased.

TABLE 23.2 Main features and statistics for the SBTF
Fishery statistics a2014–15
fishing season
2014–15
fishing season
2014–15
fishing season
2015–16
fishing season
2015–16
fishing season
2015–16
fishing season
Fishery/sector TAC
(t)
Catch
(t)
Real value
(2014–15)
TAC
(t)
Catch
(t)
Real value
(2015–16)
Purse seine
Pelagic longline
5,557 b
4,947
572 d
$33.90 million
$3.39 million
5,703 c
4,904
731 d
$30.57 million
$5.27 million
Total fishery5,5575,519$37.29 million5,7035,636$37.29 million

Fishery-level statistics2014-15 fishing season2015-16 fishing season
Effort ePurse seine: 1,016 search hours; 154 shotsPurse seine: 906 search hours; 127 shots
Fishing permits89 SFR owners initially allocated89 SFR owners initially allocated
Active vesselsPurse seine: 6
Longline: 18
Purse seine: 6
Longline: 19
Observer coverage fPurse seine: 14 shots (9.1%)
Longline: 5.87% in ETBF; 7.22% in WTBF
Purse seine: 25 shots (18.9%)
Longline: 8.7% (of hooks) in ETBF; 10.2% (of hooks) in WTBF
Fishing methodsPurse seine, pelagic longline (southern bluefin tuna is a byproduct in the longline fishery), minor line (troll and poling)Purse seine, pelagic longline (southern bluefin tuna is a byproduct in the longline fishery), minor line (troll and poling)
Primary landing portsPort Lincoln (South Australia)Port Lincoln (South Australia)
Management methodsOutput controls: TAC, ITQs, area restrictions to control incidental catches in the longline fisheryOutput controls: TAC, ITQs, area restrictions to control incidental catches in the longline fishery
Primary marketsInternational: Japan—fresh, frozenInternational: Japan—fresh, frozen
Management plan Southern Bluefin Tuna Fishery Management Plan 1995 Southern Bluefin Tuna Fishery Management Plan 1995

a Fishery statistics are provided by fishing season, unless otherwise indicated. Season is 1 December to 30 November. Real-value statistics are by financial year. b Australia voluntarily reduced its effective TAC for 2014–15 by 108 t, to account for overcatch in the 2013–14 season. The actual TAC set by the AFMA Commission was 5,665 t. c Australia carried forward ~38 t of undercatch to the 2015–16 TAC. The TAC set by the AFMA Commission was 5,665 t. d Includes some minor-line catch. e Effort only for where southern bluefin tuna was caught. f Longline observer coverage is provided by calendar year, and includes hooks observed by both human observers and the electronic monitoring system in 2014–15, and electronic monitoring only in 2015–16.
Notes: ETBF Eastern Tuna and Billfish Fishery. ITQ Individual transferable quota. SFR Statutory fishing right. TAC Total allowable catch. WTBF Western Tuna and Billfish Fishery. – Not applicable.

23.2 Biological status

Southern bluefin tuna (Thunnus maccoyii)

Southern bluefin tuna (Thunnus maccoyii) 

Line drawing: FAO

Stock structure

Southern bluefin tuna constitutes a single, highly migratory stock that spawns in the north-east Indian Ocean (off north-western Australia, south of Indonesia; Figure 23.1) and migrates throughout the temperate southern oceans.

Catch history

Troll catches of southern bluefin tuna off the east coast of Australia were reported as early as the 1920s, but significant commercial fishing for southern bluefin tuna commenced in the early 1950s with the establishment of a pole-and-live-bait fishery off New South Wales, South Australia and later (1970) Western Australia. Purse-seine gear overtook pole as the main fishing method, and catches peaked at 21,500 t in 1982. Australia's catch of southern bluefin tuna was relatively stable from 1989 to 2009 when the global TAC, and Australia's TAC, were reduced because of the poor state of the biological stock (Figure 23.2). However, the TAC has been slowly increasing with the implementation of the management procedure. Reported global catch peaked in the early 1960s at more than 80,000 t before declining steadily until around 2007 (Figure 23.3).

Recreational angling for southern bluefin tuna in Australia has been popular among game fishers for many years, and activity among the general recreational fishing sector has increased in recent years (for example, Rowsell et al. 2008). At present, the data available on the recreational catch of southern bluefin tuna are limited, and no total estimate of the national recreational catch is available. Several state surveys have taken place; however, the error associated with these surveys has been estimated to be as high as 47 per cent (Giri & Hall 2015). In 2015, a report on methods to estimate recreational catch of southern bluefin tuna was released (Moore et al. 2015). A national survey, based on this methodology, is currently under consideration.

FIGURE 23.2 Southern bluefin tuna catch and TAC (Australia), 1989–90 to 2015–16
Note: TAC Total allowable catch.
Source: Australian Fisheries Management Authority
FIGURE 23.3 Southern bluefin tuna catch (global), 1952 to 2015
Note: Total global catches exceeded reported global catches between 1995 and 2005; some scientists estimate that unreported catches surpassed 178,000 t during this period (Polacheck & Davies 2008).
Source: Commission for the Conservation of Southern Bluefin Tuna
Stock assessment

The management procedure specifies that a full quantitative stock assessment should be undertaken every three years; 2014 was the first full assessment since the 2011 adoption of the management procedure. In 2014, a revised CCSBT operating model (the quantitative model that is used to assess the spawning biomass of southern bluefin tuna, based on a variety of data sources) was used to run various scenarios to determine the impact of fishing on the stock (CCSBT 2014). The updated assessment incorporated the results of studies of close-kin genetics (Bravington et al. 2014) and the most recent data, including a scientific aerial survey index of the relative abundance of juveniles. The previous (2011) assessment reported the estimated biomass of fish 10 years and older (B10+) as a proxy for spawning biomass. Information from the close-kin genetics study indicated that fish as young as eight years of age may spawn as well, although probably not every year. Therefore, the 2014 assessment provided a revised estimate of spawning stock biomass, which took into account relative fecundity, residency time on the spawning grounds and resting times, which vary with age. Thus, although the rebuilding target of the management procedure was specified in terms of the B10+ group as spawning biomass, the updated assessment also provided an estimate of the newly defined spawning group. This newly defined group includes younger fish than the B10+ group and results in an increase in the size of the spawning stock estimate.

The 2014 assessment examined a range of sensitivity tests, including scenarios for unaccounted catch mortalities. The potential sources of unaccounted catch mortalities included recreational catches, unreported catch by members and non-members, mortalities of releases, and discarding of fish. The CCSBT Extended Scientific Committee noted that it was constrained by the lack of information and data on sources of unaccounted mortalities, and so developed a set of scenarios for sensitivity tests.

The reference set of operating models (or base case) for the assessment indicated that the spawning stock biomass remains below the interim target of 20 per cent of the unfished level. Spawning stock biomass (B8+ group) was estimated at 9 per cent of the initial unfished level (80 per cent confidence interval [CI] 8 to 12 per cent) and below the level needed to produce the maximum sustainable yield (MSY; CCSBT 2014). The spawning stock biomass of the B10+ group was estimated to be at 7 per cent of initial levels (80 per cent CI 6 to 9 per cent); the 2011 estimate was 5 per cent of initial levels (CCSBT 2014). The ratio of current fishing mortality to the level associated with MSY (FMSY) was 0.66 (range 0.39–1.00).

The estimates of current stock status varied little across the sensitivity tests, including the scenarios for unaccounted mortalities. However, the unaccounted mortality scenarios impacted on projections under the management procedure. Projections based on the reference set had a probability of rebuilding by 2035 of 74 per cent, which is in line with the 70 per cent probability level set by the CCSBT. The unaccounted mortality scenarios reduced the probability of rebuilding below the 70 per cent level. The most substantial impact was the scenario that included 1,000 t of large fish, 1,000 t of small fish and a 20 per cent underestimate of the Australian purse-seine catch. This scenario reduced the probability of rebuilding to 49 per cent. These levels of unaccounted mortality were not considered in the design of the management procedure, and the Extended Scientific Committee noted that, if they were true, they would amount to exceptional circumstances.

Stock status determination

The current mean estimate for spawning stock biomass of southern bluefin tuna is 9 per cent of unfished levels. As a result, the stock remains classified as overfished.

The global TAC that was set for 2016 was based on the management procedure's recommendation, which should result in a level of fishing mortality that facilitates rebuilding of the stock. The reference case for the updated assessment indicates reduced fishing mortality. However, there remains substantial uncertainty about the level of unaccounted catch mortality and its potential impact on stock rebuilding.

The reported 2014 global catch indicated that some members had exceeded their allocation. In addition, the Extended Scientific Committee considered the sources of unaccounted catch mortality extensively at the 2014 meeting, with new sensitivity tests added to the operating model. Further information was considered at the 2015 meeting of the Extended Scientific Committee. The total level of mortality from all sources (including releases and discards from the high-seas longline fleets, recreational fishing catch, and unreported catches by non-members and members) is unknown. However, the Extended Scientific Committee noted that it appeared that significant levels of unaccounted mortality may have occurred, and for some scenarios there was a substantial impact on the probability of achieving the rebuilding target by 2035. Therefore, it was uncertain whether the total level of fishing mortality was at the level required for rebuilding to occur in line with the management procedure. Given the uncertainty around the current level of fishing mortality and the impact on the recovery of the stock, the stock is classified as uncertain with regard to fishing mortality.

23.3 Economic status

Key economic trends

Assessment of economic performance in the wild-catch sector is complicated by the vertical integration of the wild-catch and aquaculture sectors. As noted above, most southern bluefin tuna caught are transferred to aquaculture farms off Port Lincoln. The beach price paid for live fish at the point of transfer to these farms cannot be determined, because operators are generally involved in both wild-catch and aquaculture operations. Therefore, beach prices in the fishery are estimated with reference to export unit values and costs incurred during the aquaculture phase.

In 2015–16, the gross value of production (GVP) for the SBTF—the value of the catch at the point of transfer to farming pens—was estimated as $35.8 million (Figure 23.4). This is 4 per cent lower (in real terms, 2015–16 dollars) than the value of production estimated for 2014–15. In 2015–16, export unit prices achieved for farm-gate product continued to decline—by 9 per cent, to $13.92 per kilogram—placing downward pressure on beach prices. It was the third consecutive year in which real export unit value declined for farm-gate product. In real terms, the export unit value in 2015–16 was the lowest level achieved over the 10-year period to 2015–16, and well below the average level of $21.50 achieved in the period 2005–06 to 2012–13.

The estimated value of the SBTF catch declined substantially (by 48 per cent) in 2009–10, to $28 million, following a reduction in the estimated average unit beach price from $10.47 per kilogram in 2008–09 to $6.71 per kilogram in 2009–10 (in real terms, 2015–16 dollars), and a 19 per cent decline in the quantity of southern bluefin tuna caught in the fishery. Prices then recovered, with the estimated average beach price being around $8.85 per kilogram from 2010–11 to 2013–14, and production quotas increased. Since 2013–14, GVP has declined by 12 per cent, in line with lower unit export prices achieved for farm-gate product.

The SBTF typically has very little quota latency within a fishing season, indicating that net economic returns (NER) are likely to be positive. However, in 2015–16, GVP declined, indicating that the NER of the fishery are likely to have declined in 2015–16.

The value of farmed southern bluefin tuna exports in 2015–16 (after ranching) was $132 million, a decrease of $4 million from the value achieved in 2014–15 ($136 million). Most of the farmed southern bluefin tuna is exported, mainly to Japan. In 2015–16, the Australian dollar unit price for exported southern bluefin tuna decreased by 9 per cent, despite a fall in the exchange rate of the Australian dollar relative to the yen. Export returns were supported by an increase in the volume exported, but not enough to offset the negative effect on returns from lower unit prices (Figure 23.5).

FIGURE 23.4 Real GVP of southern bluefin tuna production, 2005–06 to 2015–16
Note: GVP gross value of production.
FIGURE 23.5 Real value of southern bluefin tuna exports, by processing method, 2005–06 to 2015–16

Management arrangements

The Australian TAC is allocated to holders of statutory fishing rights in the fishery via individual transferable quotas (ITQs). The ITQs give fishers flexibility to use input combinations that result in the most efficient operation. Theoretically, transferability of ITQs between fishers also allows the catch to be taken by the most efficient operators in the fishery, since quota is expected to gravitate to the most efficient operators. However, other factors are often considered by quota holders when deciding to lease or sell quota, sometimes resulting in quota not being allocated to the most efficient user. This may limit quota transaction activity between the purse-seine operators and longline operators in some years.

Performance against economic objective

The SBTF is a high-value fishery, and analysis of recent economic trends suggests that the fishery remains profitable. However, given the biological status of the southern bluefin tuna stock, it is likely that a proportion of historical profits have been generated by unsustainable global harvest levels. Furthermore, the low biomass level of the stock poses a risk to the future flow of NER from this fishery. If current management arrangements allow the southern bluefin tuna stock to rebuild, this would be considered an improvement in the fishery's economic status. The management procedure is a significant step in the right direction. Because the procedure was only recently introduced, it is too early to assess its impact on economic performance.

23.4 Environmental status

The SBTF has approval for export until 13 December 2019. Conditions placed on the export approval include increasing confidence in the estimates of purse-seine catches, and that the management arrangements start accounting for Australia's attributable catch, including recreational and Indigenous catch, by 2018.

A level 3 ecological risk assessment (Sustainability Assessment for Fishing Effects) of 83 non-target species (6 chondrichthyans and 77 teleosts) to determine the impact of southern bluefin tuna fishing on these species assessed the risk as low (Zhou et al. 2009). The priority of the ecological risk management report is to respond to interactions with protected species (AFMA 2009).

No interactions with protected species were reported for the SBTF in 2016. Interactions with sharks and other protected species using longline gear are discussed in Chapters 21 and 24.

Southern bluefin tuna in the towcage
Matt Daniel, AFMA

23.5 References

AFMA 2009, Ecological risk management report for the Southern Bluefin Tuna Fishery, Australian Fisheries Management Authority, Canberra.

Basson, M, Hobday, AJ, Eveson, JP & Patterson, TA 2012, Spatial interactions among juvenile southern bluefin tuna at the global scale: a large scale archival tag experiment, Fisheries Research and Development Corporation report 2003/002, CSIRO, Hobart.

Bravington, MV, Grewe, PG & Davies, CR 2014, Fishery-independent estimate of spawning biomass of southern bluefin tuna through identification of close-kin using genetic markers, FRDC report 2007/034, CSIRO, Hobart.

CCSBT 2014, Report of the nineteenth meeting of the Scientific Committee, Auckland, 1–6 September 2014, Commission for the Conservation of Southern Bluefin Tuna, Canberra.

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

Giri, K & Hall, K 2015, South Australian recreational fishing survey, Fisheries Victoria internal report series 62, Victorian Department of Economic Development, Jobs, Transport and Resources, Melbourne.

Moore, A, Hall, K, Khageswor, G, Tracey, S, Hansen, S, Ward, P, Stobutzki, I, Andrews, J, Nicol, S & Brown, P 2015, Developing robust and cost-effective methods for estimating the national recreational catch of southern bluefin tuna in Australia, FRDC report 2012/022.20, ABARES, Canberra.

Polacheck, T & Davies, C 2008, Consideration of implications of large unreported catches of southern bluefin tuna for assessments of tropical tunas, and the need for independent verification of catch and effort statistics, CSIRO Marine and Atmospheric Research paper 023, CSIRO, Hobart.

Rowsell, M, Moore, A, Sahlqvist, P & Begg, G 2008, Estimating Australia's recreational catch of southern bluefin tuna, working paper CCSBT-ESC/0809/17, 13th meeting of the Scientific Committee of the CCSBT, Rotorua, New Zealand, September 2008.

Zhou, S, Fuller, M & Smith, T 2009, Rapid quantitative risk assessment for fish species in seven Commonwealth fisheries, report for AFMA, Canberra.

Chapter 24: Western Tuna and Billfish Fishery

A Williams, H Patterson and A Bath

FIGURE 24.1 Area of the Western Tuna and Billfish Fishery, 2016
TABLE 24.1 Status of the Western Tuna and Billfish Fishery
Status
Biological status a
2015
Fishing mortality
2015
Biomass
2016
Fishing mortality
2016
Biomass
Comments
Striped marlin (Kajikia audax)Subject to overfishingNot overfishedSubject to overfishingNot overfishedMost recent estimate of biomass is above the default Commonwealth limit reference point. Current fishing mortality rate exceeds that required to produce MSY.
Swordfish
(Xiphias gladius)
Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedMost recent estimate of spawning biomass is above the default Commonwealth limit reference point. Current fishing mortality rate is below that required to produce MSY.
Albacore
(Thunnus alalunga)
Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedMost recent estimate of spawning biomass is above the default Commonwealth limit reference point. Current fishing mortality rate is below that required to produce MSY.
Bigeye tuna
(Thunnus obesus)
Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedMost recent estimate of spawning biomass is above the default Commonwealth limit reference point. Current fishing mortality rate is below that required to produce MSY.
Yellowfin tuna
(Thunnus albacares)
Subject to overfishingNot overfishedSubject to overfishingNot overfishedMost recent estimate of spawning biomass is above the default Commonwealth limit reference point. Current fishing mortality rate exceeds that required to produce MSY.

Economic status
Latency remained high in 2016, with only a small proportion of the TACC caught, suggesting low NER.

a Ocean-wide assessments and the default limit reference points from the Commonwealth Fisheries Harvest Strategy Policy (DAFF 2007) are used as the basis for status determination.
Notes: MSY Maximum sustainable yield. NER Net economic returns. TACC Total allowable commercial catch.

[expand all]

24.1 Description of the fishery

Area fished

The Western Tuna and Billfish Fishery (WTBF) operates in Australia's Exclusive Economic Zone and the high seas of the Indian Ocean (Figure 24.1). In recent years, effort has concentrated off south-west Western Australia and South Australia. Domestic management arrangements for the WTBF reflect Australia's commitment to the Indian Ocean Tuna Commission (IOTC; see Chapter 20).

Fishing methods and key species

Key species in the WTBF are bigeye tuna (Thunnus obesus), yellowfin tuna (T. albacares), striped marlin (Kajikia audax)and swordfish (Xiphias gladius). Some albacore (Thunnus alalunga) is also taken.Fishing in the WTBF mainly uses pelagic longline; some minor-line fishing also occurs (Table 24.2).

Management methods

The management plan for the fishery began in 2005, although the Australian Fisheries Management Authority (AFMA) first granted statutory fishing rights in 2010. Under the management plan, output controls have been implemented in the fishery through individual transferable quotas (ITQs) for the four key commercial species. Determinations of total allowable commercial catch (TACC) are made in accordance with Australia's domestic policies, and apply to the Australian Fishing Zone and the high-seas area of the IOTC area of competence. A harvest strategy has been developed for the WTBF (Davies et al. 2008), with the intention that it be implemented if fishing effort increases in the fishery and sufficient data are available for use in the strategy. The framework includes a decision tree that defines rules and subsequent adjustments to the recommended biological catch (or level of fishing mortality) in response to standardised size-based catch rates.

The default limit reference points contained in the Commonwealth Fisheries Harvest Strategy Policy (HSP; DAFF 2007) are used to determine stock status in the WTBF. The limit reference point for biomass is 20 per cent of the unfished biomass (0.2B0), and for fishing mortality the limit reference point is the fishing mortality that would achieve maximum sustainable yield (FMSY). The IOTC determines stock status relative to target reference points, not limit reference points, resulting in a different stock status reported by the IOTC for some stocks.

As of 1 July 2015, electronic monitoring (e-monitoring) was made mandatory for all full-time pelagic longline vessels in the Eastern Tuna and Billfish Fishery and the WTBF. At least 10 per cent of video footage of all hauls is reviewed to verify the accuracy of logbooks, which are required to be completed for 100 per cent of shots.

Fishing effort

Effort in the WTBF was relatively low (<20 vessels) from the mid 1980s to the mid 1990s (Figure 24.2). Effort increased in the late 1990s, peaking at 50 active vessels in 2000, but then declined rapidly. Since 2005, fewer than five vessels have been active in the fishery each year.

FIGURE 24.2 Longline fishing effort, boat statutory fishing rights and active vessels in the WTBF, 1986 to 2016
Note: SFR Statutory fishing rights.
Source: Australian Fisheries Management Authority

Catch

Swordfish is the main target species in the WTBF, with annual catches peaking at more than 2,000 t in 2001 (Figure 24.3) and declining to a few hundred tonnes in recent years. Bigeye and yellowfin tuna are also valuable target species, although catches of these species have never been as high as for swordfish and have been more variable.

FIGURE 24.3 Total annual catch, by species, in the WTBF, 1986 to 2016
Source: Australian Fisheries Management Authority
TABLE 24.2 Main features and statistics for the WTBF

Fishery statistics a
2015
20152015201620162016
Stock TAC
(t)
Catch
(t)
Real value
(2014–15)
TAC
(t)
Catch
(t)
Real value
(2015–16)
Striped marlin1252Confidential1251Confidential
Swordfish3,000220Confidential3,000147Confidential
Albacore27Confidential23Confidential
Bigeye tuna2,000109Confidential2,00075Confidential
Yellowfin tuna5,00082Confidential5,00074Confidential
Total 10,125 440 Confidential 10,125 320 Confidential

Fishery-level statistics20152016
EffortPelagic longline: 421,185 hooks
Minor line: na
Pelagic longline: 352,274 hooks
Minor line: na
Fishing permits95 boat SFRs95 boat SFRs
Active vesselsPelagic longline: 2
Minor line: 1
Pelagic longline: 2
Minor line: 1
Observer coverage7.1% b10.2% b
Fishing methodsPelagic longline (monofilament mainline), minor line (handline, rod and reel, troll and poling), purse seinePelagic longline (monofilament mainline), minor line (handline, rod and reel, troll and poling), purse seine
Primary landing portsFremantle and Geraldton (Western Australia)Fremantle and Geraldton (Western Australia)
Management methodsInput controls: limited entry, gear and area restrictions
Output controls: TACCs, ITQs, byproduct restrictions
Input controls: limited entry, gear and area restrictions
Output controls: TACCs, ITQs, byproduct restrictions
Primary marketsInternational: Japan, United States—fresh, frozen
Domestic: fresh, frozen
International: Japan, United States—fresh, frozen
Domestic: fresh, frozen
Management plan Western Tuna and Billfish Management Plan 2005 (amended 2016); SFRs issued 2010 Western Tuna and Billfish Management Plan 2005 (amended 2016); SFRs issued 2010

a Fishery statistics are provided by calendar year to align with international reporting requirements. Value statistics are by financial year and are in 2015–16 dollars. b As of 1 July 2015, e-monitoring was made mandatory for all full-time pelagic longline vessels in the WTBF. At least 10% of video footage of all hauls are reviewed to verify the accuracy of logbooks, which are required to be completed for 100% of shots.
Notes: ITQ Individual transferable quota. na Not available. SFR Statutory fishing right. TACC Total allowable commercial catch. – Not applicable.

24.2 Biological status

Striped marlin (Kajikia audax)

Striped marlin (Kajikia audax) 

Line drawing: FAO

Stock structure

The stock structure of striped marlin in the Indian Ocean is uncertain, but the species is considered to be a single distinct biological stock for assessments. No genetic studies have evaluated striped marlin population structure in the Indian Ocean, and tagging efforts have been limited. Several transoceanic movements of striped marlin have occurred in the Indian Ocean, supporting the assumption of a single biological stock (IOTC 2014).

Catch history

Catches of striped marlin in the WTBF have always been relatively low—less than 50 t since the mid 1980s and very low (<5 t) in recent years, with 2 t taken in 2015 and 1 t in 2016 (Figure 24.4). Total international catches in the IOTC area of competence declined from around 6,000 t in 1995 to around 2,000 t in 2009 (Figure 24.5). Annual catches have increased since 2009, reaching 4,213 t in 2015, which is below the 2015 estimate of MSY (5,220 t).

FIGURE 24.4 Striped marlin catch and TACC in the WTBF, 1983 to 2016
Note: TACC Total allowable commercial catch; initial TACC for 19 months.
Source: Australian Fisheries Management Authority
FIGURE 24.5 Striped marlin catch in the IOTC area, 1970 to 2015
Note: IOTC Indian Ocean Tuna Commission.
Source: IOTC
Stock assessment

Stock assessments for striped marlin were made most recently in 2015 at the IOTC Working Party on Billfish. Three models were used: A Stock Production Model Incorporating Covariates (ASPIC), a Bayesian surplus production model and a stock reduction analysis. Results from the ASPIC model were used to provide management advice, although all models provided similar conclusions regarding stock status. The 2014 biomass was estimated to be 24 per cent of unfished (1950) levels (B2014/B1950 = 0.24) and below the level that would support MSY (B2014/BMSY = 0.65; range 0.45–1.17) (IOTC 2016). Fishing mortality was estimated to be above the level that would result in MSY (F2014/FMSY = 1.09; range 0.62–1.66).

Stock status determination

The ASPIC assessment indicates that the current biomass is above the default limit reference point (0.2B0). As a result, the Indian Ocean striped marlin stock is classified as not overfished. Fishing mortality is above FMSY, so the stock is classified as subject to overfishing.

Swordfish (Xiphias gladius)

Swordfish (Xiphias gladius) 

Line drawing: Gavin Ryan

Stock structure

Swordfish in the Indian Ocean is considered to be a single distinct biological stock. The possibility of a separate south-west Indian Ocean stock was examined in the Indian Ocean Swordfish Stock Structure project—a genetic study focused on the links between the south-west and other regions. The study found that genetic markers were consistent with a single stock in the Indian Ocean (Muths et al. 2013).

Catch history

Annual swordfish catch in the WTBF peaked at around 2,000 t in the early 2000s but has declined to below 350 t since 2005. In 2016, the annual catch was 147 t, the lowest level since 1997 (Figure 24.6). Total international catches of swordfish in the IOTC area of competence peaked in 2004 at more than 40,000 t, but declined to around 21,000 t in 2009 (Figure 24.7), likely as a result of the impacts of piracy in the western Indian Ocean. Annual catches in the IOTC area of competence have increased since 2009, reaching the highest level on record in 2015 at 41,743 t, which is above the 2015 estimate of MSY (39,400 t).

FIGURE 24.6 Swordfish catch and TACC in the WTBF, 1983 to 2016
Note: TACC Total allowable commercial catch; initial TACC for 19 months.
Source: Australian Fisheries Management Authority
FIGURE 24.7 Swordfish catch in the IOTC area, 1970 to 2015
Note: IOTC Indian Ocean Tuna Commission.
Source: IOTC
Stock assessment

In 2014, four assessment models were used to assess to the Indian Ocean–wide swordfish stock: Stock Synthesis 3 (SS3), ASPIC, a Bayesian Biomass Dynamic Model (BBDM) and an Age-Structured Integrated Analysis (IOTC 2016). The SS3 assessment was considered to be the most reliable and informative for determining the current status of the stock. The 2013 spawning biomass for the Indian Ocean–wide stock was estimated to be 74 per cent of unfished (1950) biomass (SB2013/SB1950 = 0.74; range 0.58–0.89) and well above the level that supports MSY (SB2013/SBMSY = 3.10; range 2.44–3.75) (IOTC 2016). Fishing mortality was estimated to be well below FMSY (F2013/FMSY = 0.34; range 0.28–0.40).

Stock status determination

Assessments of the ocean-wide stock indicate that swordfish biomass is above the default limit reference point (0.2B0) and that fishing mortality is below FMSY. As a result, the stock is classified as not overfished and not subject to overfishing.

Albacore (Thunnus alalunga)

Albacore (Thunnus alalunga) 

Line drawing: FAO

Stock structure

The stock structure of albacore in the Indian Ocean is uncertain, but the species is assumed to be a single biological stock for assessments. A global genetics study of albacore found that the Atlantic Ocean and Indian Ocean populations were not genetically distinguishable, and found no evidence of genetic heterogeneity within the Indian Ocean (Montes et al. 2012). However, the study was based on relatively small sample sizes, and samples were not collected across the entire distribution of albacore in the Indian Ocean. Two distinct stocks of albacore occur in the Atlantic and Pacific oceans, associated with distinct northern and southern ocean gyres. There is no northern gyre in the Indian Ocean, supporting the assumption of a single Indian Ocean albacore stock (IOTC 2014).

Catch history

Historically, albacore catches in the WTBF have been low, peaking at 115 t in 1994 and again at 94 t in 2001 (Figure 24.8). Since 2004, annual catches have been below 30 t. Total international catches in the IOTC area of competence peaked at more than 46,000 t in 2011, and have fluctuated between 30,000 t and 45,000 t since (Figure 24.9). The average annual catch over the past five years (2011–15) was approximately 35,000 t, which is lower than the 2015 estimate of MSY (38,800 t).

FIGURE 24.8 Albacore catch in the WTBF, 1983 to 2016
Source: Australian Fisheries Management Authority
FIGURE 24.9 Albacore catch in the IOTC area, 1970 to 2015
Note: IOTC Indian Ocean Tuna Commission.
Source: IOTC
Stock assessment

In 2016, five assessment models were used to assess the Indian Ocean albacore stock: SS3, ASPIC, a Statistical Catch at Age Model (SCAA), a Bayesian State-Space Production Model (BSPM) and a BBDM. The results from the SS3 model were used to determine the current status of albacore (IOTC 2016), although the results from all the models were generally consistent. Considerable uncertainty exists in the SS3 model results because of uncertainty in catch-per-unit-effort data and length composition data, and a lack of biological information on albacore stocks in the Indian Ocean (IOTC 2016).

The result of the SS3 model indicated that the current (2014) biomass was above the limit reference point (SB2014/SB1950 = 0.37; range 0.28–0.46) and above the level that supports MSY (SB2014/SBMSY = 1.80; range 1.38–2.23). Fishing mortality was estimated to be below the level that supports MSY (F2014/FMSY = 0.85; range 0.57–1.12) (IOTC 2016).

Stock status determination

The assessment indicates that the spawning biomass is above the default limit reference point (0.2B0), and so the stock is classified as not overfished. Fishing mortality across the entire IOTC area is below FMSY, and so the stock is classified as not subject to overfishing.

Bigeye tuna (Thunnus obesus)

Bigeye tuna (Thunnus obesus) 

Line drawing: FAO

Stock structure

The stock structure of bigeye tuna in the Indian Ocean is uncertain, but the species is considered to be a single distinct biological stock for assessments. The assumption of a single stock is based on a genetic study (Chiang et al. 2008) that indicated no genetic differentiation within the Indian Ocean, and tagging studies that have demonstrated large-scale movements of bigeye tuna (IOTC 2014).

Catch history

Annual catches of bigeye tuna in the WTBF varied widely between 1983 and 2004, with the highest catch of more than 900 t in 1987 and the lowest catch of less than 22 t in 1991 (Figure 24.10). Catches have been more stable since 2004, and have not exceeded 200 t. Total international catches in the IOTC area of competence have been declining from a peak of more than 160,000 t in 1999 to less than 100,000 t in recent years (Figure 24.11). Bigeye catch was 92,672 t in 2015, which is below the 2015 MSY estimate of 132,000 t, as is the five-year average catch.

FIGURE 24.10 Bigeye tuna catch and TACC in the WTBF, 1983 to 2016
Note: TACC Total allowable commercial catch; initial TACC for 19 months.
Source: Australian Fisheries Management Authority
FIGURE 24.11 Bigeye tuna catch in the IOTC area, 1970 to 2015
Note: IOTC Indian Ocean Tuna Commission.
Source: IOTC
Stock assessment

Six assessment models were used to assess the Indian Ocean bigeye stock in 2016: SS3, ASPIC, SCAA, an Age Structured Assessment Program (ASAP), a BBDM and a BSPM (IOTC 2016). The results from these assessments were similar to 2014 assessments, although with lower relative biomass and higher relative fishing mortality. The SS3 assessment captured uncertainty in the stock–recruitment relationship, as well as the influence of tagging data on the model outcomes, and was used to provide management advice. Current (2015) spawning stock biomass was estimated to be above the level that would produce MSY (SB2015/SBMSY = 1.29; range 1.07–1.51). Similarly, the assessment indicated that spawning biomass was above 20 per cent of the initial unfished level (SB2015/SB0 = 0.38; range not available). Fishing mortality was below the level associated with MSY (F2015/FMSY = 0.76; range 0.49–1.03).

Stock status determination

The SS3 assessment indicates that bigeye tuna spawning stock biomass is above the default limit reference point (0.2B0). As a result, the Indian Ocean bigeye tuna stock is classified as not overfished. Since the current spawning biomass is above the level that would produce MSY, and fishing mortality is below FMSY, the stock is classified as not subject to overfishing.

Yellowfin tuna (Thunnus albacares)

Yellowfin tuna (Thunnus albacares) 

Line drawing: FAO

Stock structure

The stock structure of yellowfin tuna in the Indian Ocean is uncertain, but the species is considered to be a single biological stock for assessments. There have been no ocean-wide genetic studies for yellowfin tuna in the Indian Ocean, but tagging studies have demonstrated large-scale movements of yellowfin tuna in the Indian Ocean, which is consistent with the assumption of a single stock (Langley et al. 2012).

Catch history

Historical catches of yellowfin tuna in the WTBF have varied widely from peaks of around 800 t in 1984 and 1995 to catches less than 15 t in 1991 and 1992 (Figure 24.12). Since the early 2000s, declining effort in the WTBF has resulted in reduced catches of yellowfin tuna. Catches have not exceeded 100 t since 2004 (Figure 24.12). Total international catches in the IOTC area of competence have generally increased with increasing demand, but declined for several years (2007–2011) because of the impacts of piracy in the north-west Indian Ocean. From 2012 to 2015, catches have remained relatively stable at around 400,000 t (Figure 24.13), which is slightly below the 2015 MSY estimate of 421,000 t.

FIGURE 24.12 Yellowfin tuna catch and TACC in the WTBF, 1983 to 2016
Note: TACC Total allowable commercial catch; initial TACC for 19 months.
Source: Australian Fisheries Management Authority
FIGURE 24.13 Yellowfin tuna catch in the IOTC area, 1970 to 2015
Note: IOTC Indian Ocean Tuna Commission.
Source: IOTC
Stock assessment

In 2016, the 2015 yellowfin tuna assessment was updated using a revised composite catch-per-unit-effort series and revised catch estimates. Two assessment models were used (BDM and SS3; IOTC 2016), although management advice for the stock is based on the results of the SS3 analysis. The results indicate that 2015 levels of fishing mortality were above the level that would achieve MSY (F2015/FMSY = 1.11; range 0.86–1.36). Current spawning biomass was estimated to be below the level associated with MSY (SB2015/SBMSY = 0.89; range 0.79–0.99) but above the default limit reference point (SB2015/SB0 = 0.29; range not available).

Stock status determination

The assessments indicate that fishing mortality is above the level associated with MSY. As a result, the yellowfin tuna stock is classified as subject to overfishing. The biomass is above the default limit reference point (0.2B0), and, as a result, the stock is classified as not overfished.

24.3 Economic status

Key economic trends

Economic surveys have not been conducted in the WTBF since 2001–02 because of the low level of fishing activity. During 2015 and 2016, 95 fishing permits were issued in the fishery. A small number of vessels have been operational in the fishery during that time (Table 24.2), with three vessels active in both the 2015 and 2016 fishing seasons. Effort decreased in the fishery from 421,185 hooks in 2015 to 352,274 hooks in 2016, and catch also decreased from 440 t in 2015 to 320 t in 2016. As in previous years, landed catch in the fishery continued to be a small proportion of the TACC during 2016. This high level of latent quota in the fishery (the extent to which the TACC is not fully caught) indicates that permit holders expect low or negative profitability from operating in the fishery.

Management arrangements

Before 2010, the WTBF was managed solely under an input control regime in which entry was limited, and gear and operating areas were restricted. In 2010, output controls were introduced in the form of species-specific TACC, allocated as ITQs. The impact of the move to ITQs has not been measured because of the low participation in the WTBF in recent years. In general, ITQs allow fishers to use input combinations that are more efficient, particularly after any unnecessary input controls are relaxed. The transferability of fishing rights between fishers can also allow more efficient allocation of fishing rights so that catch is taken by the most efficient operators in the fishery. However, the very low levels of catch relative to the TACC in the WTBF are unlikely to provide any incentive for such trade to occur, minimising any efficiency gains.

Longline hooks
AFMA

Performance against economic objective

Although a harvest strategy has not been implemented because of low levels of effort in the fishery, the current management arrangements are unlikely to be constraining fishers' ability to operate profitably. The high levels of latency experienced in the fishery are more likely to arise from market factors that affect business input costs and international tuna prices. Furthermore, since the WTBF accesses a relatively small component of broader, internationally managed ocean-wide stocks, domestic management actions to control catch are likely to have limited impact on the biomass of these stocks and, therefore, on fishers' ability to access the resource for profitable operations. Hence, the economic objective of maximising net economic returns is likely being met for the fishery, as constraints to further fishing appear to be market related rather than arising from management arrangements.

24.4 Environmental status

The WTBF has been granted continued export approval under the Environment Protection and Biodiversity Conservation Act 1999, expiring on 28 November 2019. Conditions of export approval include a requirement to develop and implement a harvest strategy in the WTBF. Because of the very low effort in the fishery, the harvest strategy has not been implemented. A revised harvest strategy that takes different levels of effort into account is currently being developed.

AFMA's ecological risk assessment examined 187 fish species in the WTBF (38 chondrichthyans and 149 teleosts), all of which were classified as being at low risk of potential overfishing, based on the level 3 Sustainability Assessment for Fishing Effects analysis (Zhou et al. 2009). Although no shark species were identified as high risk, an increase in effort could move some species to a higher-risk category. A priority action identified in the WTBF ecological risk management report is to monitor the catch of and level of interaction, with sharks. Management of shark interactions in this fishery will be reviewed if the landed amount of any one shark species exceeds 50 t within a year (AFMA 2010). Trip limits on sharks apply, depending on species.

AFMA publishes quarterly reports of logbook interactions with protected species on its website. In 2016, 300 shortfin mako sharks (Isurus oxyrinchus)were hooked in the WTBF; all were released in an unknown condition. One bentfin devil ray (Mobula thurstoni)was hooked and released in an unknown condition. Three leatherback turtles (Dermochelys coriacea)were also hooked and released alive, as were two green turtles (Chelonia mydas) and one flatback turtle (Natator depressus). One black-browed albatross (Thalassarche melanophris) was dead after being hooked. Finally, three Australian sea lions (Neophoca cinerea) were hooked and released alive.

24.5 References

AFMA 2010, Ecological risk management: report for the Western Tuna and Billfish Fishery, Australian Fisheries Management Authority, Canberra.

Chiang, H-C, Hsu, C-C, Wu, GC-C, Chang, S-K & Yang, H-Y 2008, ‘Population structure of bigeye tuna (Thunnus obesus) in the Indian Ocean inferred from mitochondrial DNA', Fisheries Research, vol. 90, pp. 305–12.

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

Davies, C, Campbell, R, Prince, J, Dowling, N, Kolody, D, Basson, M, McLoughlin, K, Ward, P, Freeman, I & Bodsworth, A 2008, Development and preliminary testing of the harvest strategy framework for the Western Tuna and Billfish Fishery, CSIRO, Hobart.

IOTC 2014, Report of the seventeenth session of the Scientific Committee, Victoria, Seychelles, 8–12 December 2014, IOTC-2014-SC-R[E], Indian Ocean Tuna Commission, Victoria, Seychelles.

—— 2016, Report of the nineteenth session of the Scientific Committee, Seychelles, 1–5 December 2016, IOTC-2016-SC-R[E], IOTC, Victoria, Seychelles.

Langley, A, Herrera, M & Million, J 2012, ‘Stock assessment of yellowfin tuna in the Indian Ocean using MULTIFAN-CL', paper presented at the 14th session of the IOTC Working Party on Tropical Tunas, Mauritius, 24–29 October 2012, IOTC-2012-WTT14-38_Rev 1, IOTC, Victoria, Seychelles.

Montes, I, Iriondo, M, Manzano, C, Arrizabalaga, H, Jiménez, E, Angel Pardo, M, Goni, N, Davies, CA & Estonba, A 2012, ‘Worldwide genetic structure of albacore Thunnus alalunga revealed by microsatellite DNA markers', Marine Ecology Progress Series, vol. 471, pp. 183–91.

Muths, D, LeCouls, S, Evano, H, Grewe, P & Bourjea, J 2013, ‘Multi-genetic marker approach and spatio-temporal analysis suggest there is a single panmictic population of swordfish Xiphias gladius in the Indian Ocean', PLoS One, vol. 8, e63558.

Zhou, S, Smith, T & Fuller, M 2009, Rapid quantitative risk assessment for fish species in major Commonwealth fisheries, report to AFMA, Canberra.

Tori lines and streamers
Dave Cranston, AFMA

Chapter 28: High-seas fisheries for non–highly migratory species

R Noriega, L Georgeson and S Nicol

A small number of Australian fishing vessels target demersal fish species (those associated with the sea floor) in high-seas areas of the south Pacific and southern Indian oceans. The fisheries resources in these areas fall under the jurisdiction of two regional fisheries management treaties: the Convention on the Conservation and Management of High Seas Fishery Resources in the South Pacific Ocean (South Pacific Regional Fisheries Management Organisation [SPRFMO] Convention), and the Southern Indian Ocean Fisheries Agreement (SIOFA). The SPRFMO Convention entered into force on 24 August 2012 and the SIOFA on 21 June 2012. Annual meetings of the SPRFMO Commission and Scientific Committee have been held since 2013. SIOFA has held annual meetings of the Meeting of the Parties, its decision-making body, since 2015; and annual meetings of its Scientific Committee since 2016.

Demersal fishing on the high seas by Australian vessels occurs under permits issued by the Australian Fisheries Management Authority (AFMA). High-seas permits allow Australian vessels to fish in high-seas areas outside the Australian Fishing Zone (AFZ), outside the Exclusive Economic Zones (EEZs) of other countries, and within the area of competence of either the SPRFMO or the SIOFA (Figures 28.1 and 28.2).

The Commonwealth Fisheries Harvest Strategy Policy (HSP; DAFF 2007) does not prescribe management arrangements for fisheries managed under the joint authority of the Australian Government and an international management body or arrangement. However, its principles guide Australia's negotiating positions in international fisheries management forums. The HSP does not apply directly to these high-seas fisheries; there is therefore no formal harvest strategy required for domestic components of these fisheries.

The South Tasman Rise (STR) is an undersea ridge that stretches beyond the AFZ and into the SPRFMO Convention area (Figure 28.3). The South Tasman Rise Trawl Fishery (STRTF) is reported in this chapter because it has not operated within the AFZ since 2007. (In previous versions of this report, the STRTF was reported separately.)

The orange roughy (Hoplostethus atlanticus) stock is the only high-seas stock that is assigned a status classification in this chapter. Orange roughy in the STR is classified as overfished. Since the fishery is closed, the stock is classified as not subject to overfishing.

Because of a lack of catch data, stock assessments and stock structure information, we are unable to provide a stock status determination for other demersal stocks caught in the SPRFMO and SIOFA areas. Stock assessments for demersal stocks caught by Australian vessels in these areas may be included in future editions of Fishery status reports.

FIGURE 28.1 South Pacific Regional Fisheries Management Organisation Convention area
FIGURE 28.2 Southern Indian Ocean Fisheries Agreement area
FIGURE 28.3 Area of the South Tasman Rise Trawl Fishery

[expand all]

28.1 Description of the fisheries

South Pacific Regional Fisheries Management Organisation Convention area

The SPRFMO Convention covers non–highly migratory fisheries resources and excludes highly migratory species listed in the United Nations Convention on the Law of the Sea (1982). The SPRFMO Convention area has historically been fished by vessels from various nations using pelagic and demersal fishing gear. The main commercial fisheries resources managed by the SPRFMO include Chilean jack mackerel (Trachurus murphyi), jumbo flying squid (Dosidicus gigas) and lower-volume demersal species such as orange roughy.

The bottom fisheries target demersal species associated with seamounts, ridges and plateaus in the central, eastern and western areas of the south Pacific Ocean. Trawl fleets from the former Union of Soviet Socialist Republics (USSR) began fishing the high seas in the south Pacific for deep-sea species in the early 1970s. These vessels fished several areas, taking pencil (or bigeye) cardinal fish (Epigonus denticulatus),orange roughy,blue grenadier (Macruronus novaezelandiae)and oreodories (Oreosomatidae) (Clark et al. 2007).

Expansion of Australia's and New Zealand's fisheries into the high seas saw the establishment of a fishery on the Louisville Ridge in 1993 and on the STR in 1997. These fisheries were predominantly fished by New Zealand and Australian vessels; other nations, including Norway, Japan, the Republic of Korea, Belize, Ukraine and Panama, also accessed these deep-sea resources, although taking lower catches (Gianni 2004).

The species composition of catches from line and trawl fishing has varied over time. Historically, Australian high-seas fishing effort targeted orange roughy using demersal and midwater trawl gear. A low level of non-trawl activity, predominantly dropline and auto-longline methods targeting other species, such as blue-eye trevalla (Hyperoglyphe antarctica),also occurred. Limited Australian gillnet effort has occurred in the past; no gillnet fishing has been recorded since 1999. Deep-sea gillnets were prohibited in 2010 under an interim measure applicable to all fishing vessels within the SPRFMO Convention area, and this gillnet prohibition was adopted in an SPRFMO Conservation and Management Measure (CMM 1.02), adopted in January 2013 (SPRFMO 2013).

Australia, as specified in SPRFMO CMM 03-0217 and since 2007, has restricted bottom-fishing effort or catch to the average annual level between 2002 and 2006. In addition, no bottom fishing occurs for the remainder of the season within 5 nautical miles of any area where fishing activities encounter evidence of a vulnerable marine ecosystem (VME). On receiving a report of the triggered area, AFMA will assess whether the area should be reopened in following seasons. Although Australia has not expanded bottom-fishing activities in areas outside the 2002 to 2006 footprint, new and exploratory fishing may be considered and approved by the SPRFMO Commission, consistent with SPRFMO CMM 03-2017. CMM 03-0217 will be reviewed at the regular meeting of the Commission in 2018. Consistent with SPRFMO CMM 02-2017 regarding its ‘Standards for the collection, reporting, verification and exchange of data' (SPRFMO 2013), Australian high-seas fishing permits require the implementation of vessel monitoring systems, mandatory observer coverage on all trawl vessels and a target of 10 per cent observer coverage per vessel on all non-trawl vessels.

In 2011, Australia completed a bottom fishery impact assessment in the SPRFMO Convention area to examine whether individual bottom-fishing activities by Australian vessels have significant adverse impacts on VMEs (Williams et al. 2011a). The study concluded that the current overall risk of significant adverse impacts on VMEs by Australian bottom trawl and bottom longline operations is low, and the impact caused by midwater trawling and droplining is negligible (Williams et al. 2011a).

The SPRFMO has adopted various CMMs, including CMMs relating to prohibiting large-scale pelagic driftnets and all deepwater gillnets, data standards, management measures for bottom fisheries, establishing a vessel monitoring system, new and exploratory fisheries, regulation of at-sea and in-port transshipments, and minimising bycatch of seabirds.

South Tasman Rise Trawl Fishery

Fishing commenced in the STRTF in 1997 when demersal trawl was used to target orange roughy. In the later years of activity in the fishery, very little orange roughy was caught; the catch was mostly smooth oreodory (Pseudocyttus maculatus)and spikey oreodory (Neocyttus rhomboidalis). The fishery has not operated since 2007.

Under the United Nations Fish Stocks Agreement,1 other countries are entitled to access the high-seas portion of the stock, provided that a cooperative management regime with consistent measures for both portions of the stock (inside and outside the EEZ) is established.

Australia and New Zealand established a memorandum of understanding for cooperative management of the orange roughy stock in the STR in 1998. The arrangement has been revised since, with both governments agreeing to set a total allowable catch of zero tonnes, but providing for the possibility of a research quota. Through this process, Australia agreed to cease fishing orange roughy in the EEZ portion of the STR.

Southern Indian Ocean Fisheries Agreement area

The SIOFA area is predominantly a bottom fishery, with limited pelagic fishing. Fishing in the SIOFA area occurs on or near seamounts and ridges in the southern Indian Ocean. The former USSR began deep-sea trawling in what is now the SIOFA area in the 1960s. USSR vessels conducted periodic deep-sea trawl research cruises on a commercial scale from the mid 1970s until the dissolution of the USSR in 1991. During the 1990s, several Ukrainian-flagged deep-sea trawl vessels operated in the area (Romanov 2003; Clark et al. 2007; Bensch et al. 2009). No catch has been recorded by Ukraine since 2001.

Deep-sea trawlers from New Zealand and Australia were reportedly fishing in the SIOFA area before 1999. In 1999, deep-sea trawling in the area increased substantially after orange roughy stocks were discovered (Japp & James 2005). In 2000, the combined catch of all deepwater species for all international vessels in the area was estimated at 40,000 t (Bensch et al. 2009), which was taken by up to 50 vessels from more than 12 nations. Accurate catch data are not available for many of these vessels because of the unregulated nature of the high-seas fishery at that time (Bensch et al. 2009). Although more vessels were thought to be fishing, only eight reported participating in the fishery to the Food and Agriculture Organization of the United Nations (FAO) in 2001.

Australian vessels have reported catch from the SIOFA area since 1999. Fishing methods have been specified on Australian high-seas permits issued by AFMA since 2008; they include midwater trawl, demersal trawl, auto-longline, dropline and trap. Gillnetting was allowed up to 2008, but there are no records of gillnetting by Australian operators in the area after 1999 (Williams et al. 2011b), and AFMA has since prohibited the use of deepwater gillnets by Australian fishing vessels.

In 2011, Australia completed a bottom fishery impact assessment in the SIOFA area to examine whether individual bottom-fishing activities by Australian vessels have significant adverse impacts on VMEs (Williams et al. 2011b). The study concluded that the current overall risk of significant adverse impacts on VMEs by Australian bottom trawl and bottom longline operations is low, and the impact caused by midwater trawling and droplining is negligible (Williams et al. 2011b).

SIOFA has adopted various CMMs, including CMMs relating to prohibiting large-scale pelagic driftnets and deepwater gillnets; interim management measures for bottom fisheries; an authorised vessel list; an illegal, unreported and unregulated vessel list; vessels without nationality; data standards and data confidentiality; and measures to regulate at-sea and in-port transshipment and vessel monitoring systems.

28.2 Catch-and-effort statistics

South Pacific Regional Fisheries Management Organisation Convention area

The total reported catch by Australian vessels in the SPRFMO Convention area was 204 t in 2014, 216 t in 2015 and 241 t in 2016 (Figure 28.4). Three Australian vessels were active in the SPRFMO Convention area in 2016: one trawl and two longline vessels.

After a peak of 4,143 t in 1998, annual catches by Australian trawl vessels in the SPRFMO Convention area have been less than 500 t for the past 10 years. The trawl catch for 2016 was 84 t, increasing from 21 t in 2015. Orange roughy comprised 99 per cent of the 2016 trawl catch (83 t).

Total non-trawl catch by Australian vessels in the SPRFMO Convention area was 157 t in 2016, a decrease from 195 t reported in 2015. Bottom longline was the only non-trawl method used in 2016. Redthroat emperor (Lethrinus miniatus) accounted for 28 per cent (44 t) of the 2016 non-trawl catch; the remainder comprised yellowtail kingfish (Seriola lalandi;18 per cent; 28 t), Robinson's seabream (Gymnocranius grandoculis; 16 per cent; 26 t), flame snapper (Etelis coruscans; 8 per cent; 13 t), jackass morwong (Nemadactylus macropterus; 5 per cent; 8 t) and other species (24 per cent; 38 t).

Total reported catch of demersal species by all fleets in the SPRFMO Convention area was 1,743 t in 2014 and 1,992 t in 2015 (Figure 28.5). Most of this catch was reported from the western SPRFMO Convention area, primarily by New Zealand and Australian vessels.

FIGURE 28.4 Australian trawl-and-line catch, by species, in the SPRFMO area of competence, 1990 to 2016

Source: Australian Fisheries Management Authority
FIGURE 28.5 Total SPRFMO catch of demersal species, 1969 to 2015
Source: SPRFMO

Southern Indian Ocean Fisheries Agreement area

Midwater and demersal trawl have contributed most of Australia's catch from the SIOFA area. Fewer than 10 catch records have been attributed to non-trawl methods over the history of the fishery, and these methods are not considered further here.

Because of confidentiality restrictions, catch data for the SIOFA area cannot be disclosed. The main species caught include blue-eye trevalla, alfonsino (Beryx splendens), hapuku (Polyprion oxygeneios) and rubyfish (Plagiogeneion spp.). One Australian-flagged vessel was active in the SIOFA area in 2016.

South Tasman Rise Trawl Fishery

TABLE 28.1 Status of the South Tasman Rise Trawl Fishery
Status
Biological status
2015
Fishing mortality
2015
Biomass
2016
Fishing mortality
2016
Biomass
Comments
Orange roughy (Hoplostethus atanticus)Not subject to overfishingOverfishedNot subject to overfishingOverfishedFishery has been closed under domestic arrangements since 2007 as a result of stock depletion.

Economic status
Fishery closed.

Catch history

Fishing commenced in the STRTF in 1997 after the orange roughy stock was discovered. Orange roughy catches peaked at 3,270 t in 1998–99 and declined thereafter (Figure 28.6). From 2001 to 2006, when fishing was occurring, less than 10 per cent of the total allowable catch was landed. Following indications of depletion of the orange roughy stock in the 2002 stock assessment and the limited fishing for several subsequent years, the STR was closed to Australian fishing vessels—both inside and outside the AFZ—in 2007.

In the later years of activity in the STRTF, catch was mostly smooth oreodory and spikey oreodory.No formal stock assessment of oreodories in the STRTF has been undertaken. However, before the fishery was closed, trends in catch and catch rates for these species indicated that stocks had been fished down. If fishing in the STRTF resumes, management arrangements for oreodories should be considered as part of the development of a revised harvest strategy, to ensure that these species are not overexploited.

FIGURE 28.6 Australian orange roughy catch, 1997–98 to 2015–16

28.3 Stock status

Stock structure

Deep-sea structures tend to attract and support fish resources because their physical and biological properties enhance local productivity and retention. Some deepwater species form dense breeding aggregations over deep-sea structures, potentially allowing high catch rates and large catches (Norse et al. 2012). Some demersal species are slow growing and long lived, and aggregations can represent the accumulation of numerous age classes recruited over many decades. Initial catch rates typically made on these aggregations are not sustainable, and typically lead to rapid declines in abundance and availability (Norse et al. 2012). Long-term sustainable yields are only a small percentage of initial high catches.

The biological stock structure of orange roughy, alfonsino and oreodories in the southern oceans—including the SPRFMO Convention area, the SIOFA area and the adjoining STRTF—is uncertain. Research indicates that there is a greater level of genetic structure in global orange roughy populations than has previously been detected (Varela et al. 2013). However, genetic studies have not detected differences between orange roughy from New Zealand and Australia. Past studies on catches and estimated biomass have identified separate and geographically distinct fishing areas for orange roughy due to substantial distances or abyssal-depth waters. These fishing areas are the STR, the northern Lord Howe Rise, the southern Lord Howe Rise, the Challenger Plateau and the West Norfolk Ridge.

The orange roughy stock in the STR is managed independently, as a discrete population, as are the orange roughy stocks in the other fishing zones in the Southern and Eastern Scalefish and Shark Fishery (Chapter 9). In 2013, the first meeting of the SPRFMO Scientific Committee recommended that work be done to identify the existence and distribution boundaries of stocks of orange roughy and alfonsino that straddle EEZ boundaries and extend from EEZs into the SPRFMO Convention area. It is likely that alfonsino on the northern Lord Howe Rise and orange roughy on the Challenger Plateau, both within the SPRFMO Convention area, constitute such straddling stocks. Under the SPRFMO Convention, such stocks should be subject to compatible management arrangements within EEZs and on the high seas. Since there is no active management of catches of these species in the high-seas areas, management units have not been defined for these stocks.

Stock assessment

The only assessment of the orange roughy stock in the STRTF used catches and catch rates in a standardised catch-per-tow analysis, as well as examining acoustic data collected during the winter spawning seasons of 1998 to 2002 (Wayte et al. 2003). Annual reported catches in the fishery declined after the first couple of years (Figure 28.6). Standardised catch-per-tow analysis (Wayte et al. 2003) indicated that catch rates declined by 92 per cent between 1997–98 and 2002–03. Anecdotal information suggests that illegal catches in 1999 may have been substantially higher than documented. These reductions in catch and catch rate, when the cumulative total reported catch was 11,341 t, indicate that the initial stock biomass was not large compared with some other orange roughy populations and had been considerably reduced by 2002–03 (Wayte et al. 2003).

No recovery was evident after this, and estimated relative abundance in 2002–03 was only 8 per cent of abundance in 1997–98 (Wayte et al. 2003). No significant acoustic marks, indicative of spawning aggregations, were apparent during industry surveys in 2000, 2001 or 2002. Although orange roughy may not form spawning aggregations in the same location every year, the absence of aggregations for several consecutive years is concerning. The assessment concluded that there was little doubt that the stock size, or the availability of fish to the fishery, had decreased dramatically after the first couple of years of the fishery and shown no signs of recovery. The fishery has not been surveyed since 2002.

The only other stock for which an assessment has been published is orange roughy in the western SPRFMO area of competence (Clark et al. 2010). Several methods have been used to make preliminary assessments of orange roughy stocks fished by New Zealand vessels. Clark et al. (2010) present two analyses:

  • a standardised catch-per-unit-effort (CPUE) analysis using tow-by-tow data between 1992–93 and 2006–07, at the level of all fishing grounds and individual fishing grounds
  • a meta-analysis that related unexploited orange roughy biomass to physical characteristics of each seamount; 59 seamounts were analysed, and yield estimates were based on a proportion of estimated unfished biomass.

Outcomes from the catch rate–based analyses indicated that the CPUE for the north-west Challenger Plateau ground was variable, with perhaps a slow increase overall. However, Clarke et al. (2010) concluded that caution was needed when interpreting these CPUE trends as indices of stock abundance. The CPUE data for all subareas examined showed sequential fishing of locations and a subsequent reduction in the CPUE at locations fished in the past, indicating that the overall CPUE is biased upwards over time; high catch rates may be maintained by sequential movement of activity to new fishing areas.

The seamount meta-analysis gave a total biomass estimate for orange roughy on all 59 seamounts of 83,800 t. Estimated biomass on two of the major fishing grounds was 8,800 t for the north-west Challenger Plateau and 4,130 t for Lord Howe Rise. The estimated maximum constant yield (MCY) for the north-west Challenger Plateau was 130 t, and the maximum annual yield (MAY) was 170 t. The estimated MCY for Lord Howe Rise (north and south structures combined) was 60 t per year, and the MAY was 80 t per year. Using the analyses of Clark et al. (2010), Penney (2010) provided sustainable yield estimates based on 0.5MB0 (half the natural mortality rate × unexploited biomass; Gulland 1971) of 198 t for the north-west Challenger Plateau and 93 t for Lord Howe Rise.

Clark et al. (2010) noted that the number of seamount features identified within the area used for the meta-analysis is lower than the true number. As a result, potential total biomass of orange roughy in the area could be higher than that estimated through the habitat-based method. The authors also highlighted uncertainties with these assessment methods that reduce the reliability of the results. These uncertainties include the utility of broadscale catch rate–based analyses for spatially and temporally aggregating species, the impact of potential underestimation or overestimation of habitat area, and the potential overestimation of productivity through the use of long-term average recruitment and accumulated biomass.

Woodhams et al. (2012) assessed the sustainability of harvest rates of species targeted by Australian vessels in these high-seas fisheries. The study concluded that only a small proportion of the total assumed habitat area for the target species has been fished by Australian vessels and none of the stocks targeted by Australia's high-seas fishing operations have been classified as overfished or subject to overfishing. In 2013, Australia's high-seas fisheries were reaccredited for five years under part 13 of the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). One of the conditions associated with this renewed accreditation is that the Australian Government Department of Agriculture and Water Resources, in conjunction with AFMA, must continue to investigate key non–highly migratory species or stocks harvested under Australia's high-seas permits, with a view to improving certainty in future stock assessments. This has been translated into several recommendations in the SPRFMO scientific work plan adopted by the SPRFMO Commission.

Stock status determination

Insufficient information is available to enable the fishery-wide determination of stock status for any of the high-seas demersal fish stocks in the SPRFMO or SIOFA areas. However, the assessment of orange roughy in the STR indicates that the stock biomass had been overfished (Table 28.1). The life history characteristics of orange roughy may make the recovery of the stock a very slow process—possibly in the order of decades, given the estimated level of depletion. Although the fishery has not been surveyed since 2002, in the absence of any new information, the stock remains classified as overfished.Since the fishery is closed, the stock is classified as not subject to overfishing.

28.4 Economic status

The gross value of production is not available for the SPRFMO and SIOFA areas for confidentiality reasons. The number of active vessels operating during the 2016 fishing season was fewer than five in the two fisheries combined. Given limited catches in recent years, the value of the fisheries would be relatively low compared with other Australian fisheries.

The STRTF has been assessed as overfished, and so stocks are below the level associated with maximum economic yield. The fishery has been closed since 2007, so its economic status has not been assessed.

28.5 Environmental status

Deep-sea fisheries generally operate at depths of 200–1,600 m, on continental slopes or isolated oceanic structures such as ridges, seamounts and banks (FAO 2012). The depths and distances from the coast pose challenges to research, assessment and management of the effects of fishing on the environment and on target stocks (FAO 2012).

Impact assessment of bottom fishing

Under the United Nations General Assembly resolutions on sustainable fisheries (specifically, paragraph 83a of resolution 61/105, and paragraph 119(a) of resolution 64/72), states are called on to assess, on the basis of the best available scientific information, whether individual bottom-fishing activities would have a significant adverse impact on VMEs, and to ensure that these activities are managed to prevent such impacts or are not authorised to proceed. This obligation was reflected in the SPRFMO interim measures (SPRFMO 2007), resulting in the development and adoption by the SPRFMO of a standard for impact assessment of bottom fisheries (SPRFMO 2012), compatible with the FAO deepwater guidelines (FAO 2009). The 2014 meeting of the SPRFMO adopted a binding CMM to give effect to these resolutions (SPRFMO 2014).

The STRTF is included as a high-seas fishery under the List of Exempt Native Specimens under the EPBC Act until 18 May 2018. No ecological risk assessment has been done because the STRTF has been closed since 2007.

The South Tasman Rise Commonwealth Marine Reserve, which came into effect in 2007, overlaps with the STRTF (Figure 28.3). The reserve covers 27,704 km2, including several seamounts. Commercial fishing is not permitted in the reserve. Several other marine reserves occur in the vicinity of the STRTF (Figure 28.3).

As noted in Section 28.1, Australia completed bottom-fishing impact assessments for demersal fishing activities in the south Pacific and southern Indian oceans in 2011 (Williams et al. 2011a, b). The impact assessments for both areas concluded that the current overall risk of significant adverse impacts on VMEs by Australian vessels fishing with bottom trawls and bottom-set auto-longlines was low, primarily because of the low fishing effort and the small number of areas of high fishing intensity. The assessments also concluded that the current overall risk of significant adverse impacts on VMEs from midwater trawling and droplining by Australian vessels was negligible (Williams et al. 2011a, b), based on the low level of fishing effort, the small number of areas of high fishing intensity and the effects of current management arrangements.

List of exempt native specimens

Under part 13A of the EPBC Act, Australian fisheries are assessed to ensure that they are managed in a manner that does not lead to overfishing, and that fishing operations are managed to minimise their impact on the structure, productivity, function and biological diversity of the ecosystem. High-seas permits are authorised under the EPBC Act until 18 May 2018.

Since 2010, AFMA observers have recorded few interactions with protected species. No interactions with protected species were reported by AFMA observers or in logbooks in 2016.

28.6 References

Bensch, A, Gianni, M, Greboval, D, Sanders, J & Hjort, A 2009, Worldwide review of bottom fisheries in the high seas, FAO Fisheries and Aquaculture Technical Paper 522, Food and Agriculture Organization of the United Nations, Rome.

Clark, MR, Vinnichenko, VI, Gordon, JDM, Beck-Bulat, GZ, Kukharev, NN & Kakora, AF 2007, ‘Large-scale distant-water trawl fisheries on seamounts', in TJ Pitcher, T Morato, PJB Hart, MR Clark, N Haggan & RS Santos (eds), Seamounts: ecology, fisheries and conservation, Fish and Aquatic Resources Series 12, Blackwell, Oxford, United Kingdom.

——, Dunn, MR & Anderson, OF 2010, Development of estimates of biomass and sustainable catches for orange roughy fisheries in the New Zealand region outside the EEZ: CPUE analyses, and application of the ‘seamount meta-analysis' approach, New Zealand Fisheries Assessment Report 2010/19, Ministry of Fisheries, Wellington.

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

FAO 2009, International guidelines for the management of deep-sea fisheries in the high seas, FAO, Rome.

—— 2012, Deep-sea fisheries in the high seas: ensuring sustainable use of marine resources and the protection of vulnerable marine ecosystems, FAO, Rome.

Gianni, M 2004, High seas bottom trawl fisheries and their impacts on the biodiversity of vulnerable deep-sea ecosystems: options for international action, International Union for Conservation of Nature, Gland, Switzerland.

Gulland, JA 1971, The fish resources of the ocean, Fishing News (for FAO), West Byfleet, United Kingdom.

Japp, DW & James, A 2005, ‘Potential exploitable deepwater resources and exploratory fishing off the South African coast and the development of the deepwater fishery on the South Madagascar Ridge', in R Shotton (ed.), Deep Sea 2003: conference on the governance and management of deep-sea fisheries, part 1, Conference papers, FAO Fisheries Proceedings 3/1, pp. 162–8.

Norse, EA, Brooke, S, Cheung, WWL, Clark, MR, Ekeland, I, Froese, R, Gjerde, KM, Haedrich, RL, Hepell, SS, Morato, T, Morgan, LE, Pauly, D, Sumaila, R & Watson, R 2012, ‘Sustainability of deep-sea fisheries', Marine Policy, vol. 36, pp. 307–20.

Penney, AJ 2010, ‘An approach to estimation of sustainable catch limits for orange roughy in the SPRFMO area', paper SWG-09-DW-02 to the ninth meeting of the South Pacific Regional Fisheries Management Organisation Scientific Working Group, October 2010.

Romanov, EV (ed.) 2003, Summary review of Soviet and Ukrainian scientific and commercial fishing operations on the deepwater ridges of the southern Indian Ocean, FAO Fisheries Circular 991, FAO, Rome.

SPRFMO 2007, Interim measures adopted by participants in negotiations to establish South Pacific Regional Fisheries Management Organisation, third meeting of SPRFMO participants, 4 May 2007, Reñaca, Chile.

—— 2012, Bottom fishery impact assessment standard, third session of the Preparatory Conference, February 2012, Santiago, Chile.

—— 2013, Report on the first meeting of the Commission of the South Pacific Regional Fisheries Management Organisation, annex N, 28 January – 1 February 2013, Auckland, New Zealand.

—— 2014, Report on the second meeting of the Commission of the South Pacific Regional Fisheries Management Organisation, 27–31 January 2014, Manta, Ecuador.

Varela, AI, Ritchie, PA & Smith, PJ 2013, ‘Global genetic population structure in the commercially exploited deep-sea teleost orange roughy (Hoplostethus atlanticus)based on microsatellite DNA analysis', Fisheries Research, vol. 140, pp. 83–90.

Wayte, S, Bax, N, Clark, M & Tilzey, R 2003, ‘Analysis of orange roughy catches on the South Tasman Rise 1997–2002', paper for the Orange Roughy Assessment Group, CSIRO, Hobart.

Williams, A, Franziska, A, Fuller, M, Klaer, N & Barker, B 2011a, Bottom fishery impact assessment, Australian report for the SPRFMO, CSIRO Marine and Atmospheric Research, Hobart.

——, Franziska, A, Fuller, M, Klaer, N & Barker, B 2011b, Bottom fishery impact assessment, Australian report for the Southern Indian Ocean Fisheries Agreement, CSIRO Marine and Atmospheric Research, Hobart.

Woodhams, J, Stobutzki, I, Noriega, R & Roach, J 2012, Sustainability of harvest levels in the SPRFMO and SIOFA high seas areas by Australian flagged vessels, ABARES, Canberra.

Footnotes

1www.un.org/depts/los/convention_agreements/convention_overview_fish_stocks.htm

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Last reviewed:
13 Feb 2018