Torres Strait Fisheries

​​​Chapter 15: Torres Strait fisheries

A Williams and K Mazur

FIGURE 15.1 Area of the Torres Strait fisheries

Torres Strait is located between Cape York Peninsula (north Queensland) and Papua New Guinea (PNG; Figure 15.1). It connects the Arafura and Coral seas, and is an important shipping route. There are hundreds of islands and reefs in Torres Strait, with 17 island communities plus several communities in the Northern Peninsula Area on Cape York. The area produces seafood for local consumption, and for sale in Australia and overseas. Local seafood is a primary food source for Torres Strait Islanders, as well as being central to traditional island culture and an important source of income.

The 1985 Torres Strait Treaty between Australia and PNG established the boundaries between the two nations and provides for joint management of the shared marine resources. The treaty is concerned with sovereignty and maritime boundaries, protection of the marine environment, and optimum use of commercial resources in the region. It also establishes the Torres Strait Protected Zone (TSPZ; Figure 15.1), in which each nation exercises sovereign jurisdiction over migratory fish and sedentary species in its own waters. The principal purpose of establishing the TSPZ is to acknowledge and protect the way of life and livelihood of the Traditional Inhabitants of the area. This includes protecting traditional fishing methods and rights of free movement.

The management area for each Australian fishery in Torres Strait extends south of the TSPZ (Figure 15.1). In each fishery, this area of the management zone is referred to as the ‘outside but near area'. The boundary of the outside but near area for each fishery varies; these boundaries are shown in the fishery maps in subsequent chapters.

Under the treaty, Australia and PNG are required to cooperate on the conservation and management of the commercial fisheries in the TSPZ; they also engage in regular bilateral discussions. This cooperation includes negotiating and setting catch-sharing provisions for several Torres Strait fisheries under article 23 of the treaty. Catch sharing includes the development of subsidiary conservation and management arrangements under article 22 of the treaty.

In Australia's area of the TSPZ, traditional fishing and commercial fisheries are managed by the Torres Strait Protected Zone Joint Authority (PZJA), which was established under the Torres Strait Fisheries Act 1984 (TSF Act). The PZJA comprises the ministers from the Australian and Queensland governments responsible for fisheries, and the Chair of the Torres Strait Regional Authority (TSRA). The TSRA (an Australian Government statutory authority) was established in 1994 under the Aboriginal and Torres Strait Islander Commission Act 1989 (now the Aboriginal and Torres Strait Islander Act 2005), and has responsibility for managing programs that aim to improve the way of life and livelihood of Torres Strait Islanders and Aboriginal people living in Torres Strait.

On 7 August 2013, the High Court of Australia held that Commonwealth and Queensland legislation that prohibited fishing for commercial purposes without a licence did not extinguish the native title rights of certain Torres Strait communities to take resources from defined areas. In practice, this means that native title holders are still required to comply with Commonwealth and Queensland licensing requirements to undertake commercial fishing, but may do so without extinguishing their non-exclusive native title rights.

Two Australian commercial fishing sectors operate in Torres Strait: the Traditional Inhabitant sector, operating under Traditional Inhabitant Boat (TIB) licences; and the non–Traditional Inhabitant sector, operating under Transferable Vessel Holder (TVH) licences. TIB licences are available only to fishers who satisfy the Traditional Inhabitant requirements. TVH licences are issued to other commercial fishers. Catch-and-effort reporting using logbooks is mandatory for TVH licence holders, whereas a voluntary docket-book system is used by fish receivers for recording the commercial catch of TIB fishers.

The commercial fisheries currently managed by the PZJA are prawn, tropical rock lobster, Spanish mackerel, reef line, bêche-de-mer (sea cucumber), trochus (top shell), pearl shell, crab, barramundi and traditional fishing (including turtle and dugong). Five of these fisheries—prawn, tropical rock lobster, pearl shell, Spanish mackerel, and turtle and dugong—are article 22 fisheries that are jointly managed by PNG and Australia. For Australian fishers, the Torres Strait Tropical Rock Lobster Fishery is the most commercially valuable of the Torres Strait fisheries, with a gross value of production of $14.3 million (376 t) in the 2015–16 financial year. This is followed by the Torres Strait Prawn Fishery (590 t, worth $8.9 million in 2015–16).

The Commonwealth Fisheries Harvest Strategy Policy (HSP; DAFF 2007) does not prescribe management arrangements for fisheries jointly managed by the Australian Government and other (domestic or international) management agencies, such as the fisheries in Torres Strait. The PZJA has asked its management forums to provide advice on the application of the HSP to the Torres Strait fisheries, and a harvest strategy for the Torres Strait Prawn Fishery was implemented in 2011 (AFMA 2011). There are no harvest strategies currently in place for any other Torres Strait fisheries.

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15.1 References

AFMA 2011, Harvest strategy for the Torres Strait Prawn Fishery, Australian Fisheries Management Authority, Canberra.

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

Chapter 16: Torres Strait Finfish Fishery

N Marton, A Williams and K Mazur

FIGURE 16.1 Area of the Torres Strait Finfish Fishery
TABLE 16.1 Status of the Torres Strait Finfish Fishery
Status
Biological status
2015
Fishing mortality
2015
Biomass
2016
Fishing mortality
2016
Biomass
Comments
Coral trout
(Plectropomus spp., Variola spp.)
Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedManagement strategy evaluation testing suggests that current catches are well below the level likely to lead to biomass declines. Most recent biomass estimate indicated a biomass above 0.6B0.
Spanish mackerel
(Scomberomorus commerson)
Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedCurrent fishing mortality rate is below that required to produce MSY. Most recent estimates of biomass are above B20.

Economic status
Estimates of NER are not available. Economic performance in 2015–16 remains uncertain despite an increase in GVP, because of the lack of clarity around fishing effort levels by the TIB sector. The first export of live coral trout from the fishery in 2016–17 is a positive sign for NER.

Notes: B0 Unfished biomass. B20 20 per cent of unfished biomass. GVP Gross value of production. MSY Maximum sustainable yield. NER Net economic returns. TIB Traditional Inhabitant Boat.

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16.1 Description of the fishery

Area fished

Most commercial fishing in the Torres Strait Finfish Fishery (TSFF) takes place in the north-eastern region of Torres Strait (Figure 16.1). A large area of the fishery west of 142°32'E is closed to commercial fishing for the Torres Strait Finfish (Reef Line) Fishery (TSFRLF).

Fishing methods and key species

The TSFF has two components: the Torres Strait Spanish Mackerel Fishery (TSSMF) and the TSFRLF. Two commercial fishing sectors—the Traditional Inhabitant Boat (TIB) and non-TIB sectors—and the Islander subsistence sector participate in the TSSMF and the TSFRLF.

The TSSMF targets Spanish mackerel (Scomberomorus commerson), primarily by trolling from small dories or dinghies tendered to a primary vessel or operating independently. Byproduct is a relatively minor component of catch in the TSSMF. Most of the byproduct is other mackerel species (grey, school, spotted and shark mackerel), but small quantities of reef fish, including coral trout, are also retained (AFMA 2005; Begg et al. 2006).

The TSFRLF is a multispecies demersal hook-and-line fishery targeting mainly coral trout (Plectropomus spp.), with smaller catches of other groupers (Serranidae), mackerels (Scombridae), snappers (Lutjanidae), emperors (Lethrinidae) and trevally (Carangidae). The most recent data indicate that coral trout make up around 90 per cent of the retained commercial catch (by weight) for both the TIB and non-TIB sectors, while barramundi cod and rock cods represent 5 per cent, and red emperor, other emperors and trevally represent 3 per cent.

Both sectors have historically discarded more than half their total catch, in numbers, as bycatch (Williams et al. 2008). The TIB sector retains a wider range of species than the non-TIB sector, mainly for subsistence (Busilacchi et al. 2012, 2013).

A variety of fishing gears, including hook and line, nets, spears and traps, are used by subsistence fishers in the TSSMF and the TSFRLF. Estimated yields of reef fish for the subsistence fishing sector are similar to those for the TIB and non-TIB commercial sectors combined (Busilacchi 2008; Busilacchi et al. 2013). However, the species composition of the subsistence and commercial catches differs: traditional subsistence fishing takes predominantly trevallies (Carangidae), mullet (Mugilidae), sardines (Clupeidae) and rabbitfish (Siganidae).

Management methods

The fishery is managed through both input controls (limited entry, vessel restrictions and prohibited species) and output controls (size limits and amount of leased quota).

A management plan for the TSFF was finalised in 2013. The plan provides for the setting of a total allowable commercial catch. Quota in the TSFF is entirely owned by Traditional Inhabitants, and non-TIB fishers are required to operate by leasing a quota under a temporary licence (called a ‘sunset licence'). These operators lease quota for Spanish mackerel, coral trout and other TSFRLF species each year through the Torres Strait Regional Authority.

Although the Commonwealth Fisheries Harvest Strategy Policy (HSP; DAFF 2007) does not apply to fisheries jointly managed by the Australian Government and other (domestic or international) management agencies, the HSP does represent the government's preferred approach to management. A formal harvest strategy for the TSFF is being developed.

Fishing effort

Effort in the fishery has decreased from peaks in the early 2000s. Several factors have contributed to the decline, including the voluntary surrender of Transferable Vessel Holder (TVH) fishing licences, government-funded structural adjustment and logistical difficulties relating to freezer capacity. The fishery for coral trout on the Queensland east coast focuses primarily on live export (QDAFF 2013). The removal of the ban on live exports in Torres Strait has previously done little to increase activity in the TSFRLF, primarily because of difficulties and costs associated with transporting live fish from remote areas. In 2017, live coral trout were exported for the first time.

Catch

Catch in the TIB and TVH sectors has followed the trends in effort, discussed above.

TABLE 16.2 Main features and statistics for the TSFF
Fishery statistics a 2014–15 fishing season2014–15 fishing season2015–16 fishing season2015–16 fishing season
Stock Catch
(t) b
Real value (2014–15)
Catch
(t) b
Real value (2015–16)
Coral trout20.6Confidential38.7Confidential
Spanish mackerel83.9Confidential86.9Confidential
Other1.7Confidential3.9Confidential
Total fishery 106.1 $1.06 million 129.5 $1.2 million


Fishery-level statistics
2014–15 fishing season2015–16 fishing season
Effort (days)
TSSMF
TSFRLF
Spanish mackerel:
TIB—not available
Sunset permits c —394 operation-days, 721 tender-days
Coral trout:
TIB—not available
Sunset permits—151 (coral trout operation- and tender-days), 153 (all TSFRLF species operation- and tender-days)
Spanish mackerel:
TIB—not available
Sunset permits—412 operation-days, 764 tender-days
Coral trout:
TIB—not available
Sunset permits—344 coral trout operation-days, 344 tender-days (same for all TSFRLF species)
Fishing permitsTIB: 210 mackerel endorsements, 194 line endorsements
Sunset permits: 6 mackerel and/or line licences
TIB: 143 mackerel endorsements, 123 line endorsements
Sunset permits: 7 mackerel and/or line licences
Active vessels
TSSMF
TSFRLF
Spanish mackerel:
TIB—not available
Sunset permits—5
Coral trout:
TIB—not available
Sunset permits—2
Spanish mackerel:
TIB—not available
Sunset permits—5
Coral trout:
TIB—not available
Sunset permits—2
Observer coverage0 days0 days
Fishing methodsCoral trout and mixed reef species: handline, rod and line
Spanish mackerel: trolled baits, lures and handlines
Coral trout and mixed reef species: handline, rod and line
Spanish mackerel: trolled baits, lures and handlines
Primary landing portsCairns (Queensland); Torres Strait Island fish receivers on Erub (Darnley), Masig (Yorke) and Mer (Murray) islandsCairns (Queensland); Torres Strait Island fish receivers on Erub (Darnley), Masig (Yorke) and Mer (Murray) islands
Management methodsInput controls: limited entry, vessel restrictions, prohibited species
Output controls: size limits, amount of leased quota
Input controls: limited entry, vessel restrictions, prohibited species
Output controls: size limits, amount of leased quota
Primary marketsDomestic: frozen
International: frozen
Domestic: frozen
International: frozen
Management plan Torres Strait Finfish Fishery Management Plan 2013 Torres Strait Finfish Fishery Management Plan 2013

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 and are in 2015–16 dollars. b Catch figures include both TIB and non-TIB catch; however, reporting by the TIB Sector is not mandatory, so additional unreported catch and fishing effort are likely. c All finfish and Spanish mackerel quotas in Torres Strait are held in trust and managed by the Torres Strait Regional Authority on behalf of the TIB Sector. ‘Sunset' permits are permits that allow non–Traditional Inhabitant fishers to fish in Torres Strait, and take finfish and Spanish mackerel leased from the TIB Sector. Sunset permits are issued each year and expire on 30 June each year. Six sunset permits are available for primary boats that carry a small number of tenders.
Notes: TIB Traditional Inhabitant Boat. TSFRLF Torres Strait Finfish (Reef Line) Fishery. TSSMF Torres Strait Spanish Mackerel Fishery.

16.2 Biological status

Coral trout (Plectropomus spp., Variola spp.)

Coral trout (Plectropomus spp., Variola spp.) 

Line drawing: FAO

Stock structure

The biological stock structure of coral trout in Torres Strait remains uncertain. Therefore, the status is reported for the Torres Strait fishery rather than for individual stocks.

Catch history

Commercial catch of coral trout in the TSFRLF peaked in 2003–04 at 132 t before falling to below 50 t in 2007–08 (Figure 16.2). Catch has remained below this level since then.

FIGURE 16.2 Catch history for coral trout in the TSFRLF, 2002–03 to 2015–16
Source: Australian Fisheries Management Authority
Stock assessment

The coral trout stock in the TSFRLF has not been formally assessed. However, a management strategy evaluation (MSE) was undertaken for the stock using catch data up to 2004 (Williams et al. 2007, 2011). Four constant-catch scenarios, ranging from 80 to 170 t, were tested. All achieved a biomass of at least 70 per cent of the assumed unfished levels by 2025. The MSE also evaluated the effects of spatial and seasonal closures, and minimum size limits on achieving management objectives. Changes in the management and operation of the fishery since the MSE was completed may have diminished the relevance of the results for informing current management. A formal stock assessment will be required to estimate the current level of relative biomass.

Stock status determination

In the absence of a formal stock assessment, the status of the coral trout stock is evaluated against the results of the MSE, combined with a comparison of the 2015–16 catch with the historical catch record (Figure 16.2). The biomass in 2004 was estimated to be more than 60 per cent of unfished levels (Williams et al. 2011, 2007). Commercial catch in recent years has been below the historical catch levels and well below the lowest catch level simulated in the MSE (80 t per year). The results of the 80 t catch simulation indicated that the stock would increase to more than 80 per cent of the unfished biomass within 20 years at that catch level (Williams et al. 2007, 2011). As a result, the stock is classified as not overfished and not subject to overfishing.

Spanish mackerel (Scomberomorus commerson)

Spanish mackerel (Scomberomorus commerson) 

Line drawing: FAO

Stock structure

Spanish mackerel in Torres Strait is thought to comprise a separate biological stock from stocks on the east coast and further west (Begg et al. 2006; Buckworth et al. 2007).

Catch history

Annual catches of Spanish mackerel declined from a peak of 251 t in 2000–01 to around 70 t in 2008–09 and have remained at approximately 80 to 100 t since (Figure 16.3).

FIGURE 16.3 Catch history for Spanish mackerel in the TSSMF, 2000–01 to 2015–16
Source: Australian Fisheries Management Authority
Stock assessment

The stock assessment of Spanish mackerel in 2006 (Begg et al. 2006) was updated in 2016 using data to 2014 (O'Neill & Tobin 2016). The updated assessment used an integrated age-structured model and input data on catch, effort and length-at-age of Spanish mackerel. The updated assessment did not use the model region structure or spatial catch data used by Begg et al. (2006) because of a large amount of missing or imprecise location data.

Four separate analyses were run to examine the effects of uncertainty in natural mortality, assumed historical catches and changes in catch reporting since the implementation of a new non-Indigenous commercial logbook in 2003. Each analysis used a different combination of two alternative scenarios for natural mortality, historical catch series and catch-per-unit-effort (CPUE). Natural mortality was either estimated by the model, or fixed at 0.3 to be consistent with values used in the previous assessment. The two historical catch series assumed that Indigenous catches were 18.5 per cent of non-Indigenous catches in years when Indigenous catch data were considered to be under-reported, or that reported non-Indigenous catches were multiplied by 1.75 in all years to examine the effects of larger historical harvests (under-reporting) on stock status outcomes. The two alternative CPUE standardisations assumed that the implementation effects of the new logbook were either constant across vessels or varied among vessels.

Across the four analyses, maximum sustainable yield (MSY) estimates ranged from approximately 140 to 210 t, and the effort required to maintain MSY (EMSY) ranged from 800 to 2,000 primary vessel-days. The 2014 spawning biomass was estimated to be between approximately 40 and 60 per cent of unfished (1940) levels (SB2014/SB1940 = 0.4–0.6), and the current (2014) fishing mortality rate was estimated to be below the level that would produce MSY (F2014/FMSY = 0.2–0.6) (O'Neill & Tobin 2016). However, the maximum fishing mortality estimated across the past five years (2010 to 2014) was approximately equal to FMSY for two of the analyses, including the analysis with inflated historical non-Indigenous catches.

Unlike the 2006 stock assessment, the updated assessment was not used to evaluate the performance of different fishing strategies through formal MSE. However, the assessment was reviewed by the Torres Strait Finfish Scientific Technical Working Group, which recommended that the Torres Strait Finfish Working Group consider a recommended biological catch of 125 t of Spanish mackerel for the 2017–18 fishing season (AFMA 2016). This recommendation was based on the need for a precautionary approach to account for uncertainties in the assessment, and a preference to maintain the stock at levels above B40 and closer to B60.

The potential for hyperstability in the catch rates of Spanish mackerel in Torres Strait remains a concern. Hyperstability occurs when catch rates are maintained while the underlying abundance declines. Hyperstability is frequently observed in fisheries that target schooling species such as the Spanish mackerel fishery, where most fishing activity is concentrated on large spawning aggregations around Bramble Cay. Although Begg et al. (2006) recommended the collection of finer-scale spatial and temporal data to be reported by fishers to improve the standardisation of catch rates and provide a more robust index of abundance, the reporting of more precise catch and effort data has not improved.

Stock status determination

Although there is no formal target or limit reference point for the fishery, 0.2B0 is the proxy limit reference point specified in the HSP and is used for status determination in the absence of an agreed limit reference point. The 2014 estimates of Spanish mackerel biomass (between 0.4B0 and 0.6B0) were above 0.2B0. As a result, the stock is classified as not overfished. Reported catches since 2007–08 have been below the range of MSY estimates in the 2016 assessment, and fishing mortality in 2014 was estimated to be below FMSY. On this basis, the stock is classified as not subject to overfishing.

16.3 Economic status

Key economic trends

In 2015–16, the catch of coral trout increased but the prices declined (Figure 16.4). The increase in catch of Spanish mackerel and coral trout was reflected in higher gross value of production, which increased by 7 per cent to $1.2 million in 2015–16.

Quota leasing arrangements were introduced in 2008 following a structural adjustment in the fishery. The amount of quota leased for each fishing season is determined by the Torres Strait Regional Authority, based on the level of interest from non-TIB fishers and the amount of quota that Torres Strait community representatives are willing to make available (TSFFWG 2010). Leasing arrangements are likely to generate some positive economic returns to the Torres Strait community because revenue from leasing activity is invested in capacity building for TIB fishers (TSRA 2015). Revenue generated from leased quota was $215,000 in 2014–15 (TSRA 2015).

FIGURE 16.4 Real GVP and average price per kilogram for the TSFF, 2005–06 to 2015–16
Note: GVP Gross value of production.

Management arrangements

The switch from TVH endorsements to the new leasing arrangements aims to increase community revenue to Traditional Inhabitants of Torres Strait. Leasing arrangements allow quota to be leased to non-TIB fishers, with the leasing revenue used for capacity building of the TIB fishing industry (TSRA 2013).

The Torres Strait Finfish Fishery Management Plan 2013 requires harvest levels to be set at or below levels that maintain biologically viable stocks of target and non-target species, following consultation with the Torres Strait Fisheries Management Advisory Committee and other stakeholders.

Performance against economic objective

The key objectives of the TSFF management plan are to acknowledge and protect the traditional way of life of Traditional Inhabitants, including their rights in relation to traditional fishing for finfish, and to conserve resources in a way that minimises the impact on the marine environment. Optimising economic viability of the fishery is one objective, but, unlike fisheries solely managed by the Australian Government, targeting maximum economic yield is not a key focus. The quota leasing arrangements in the fishery provide a means to meet the objectives under the Torres Strait Treaty to promote economic development and employment for Traditional Inhabitants (TSFMAC 2012).

Leasing revenue is intended to provide investment funding to build the capacity of Traditional Inhabitant fishing industries. In 2014–15, $4,000 in grant payments were disbursed, leaving the Finfish Quota Trust account with a closing balance of $1.1 million at the end of the financial year (TSRA 2015). In 2015–16, $1,000 in grant payments were disbursed, leaving the Finfish Quota Trust account with a closing balance of $1.3 million at the end of the financial year (TSRA 2016). TSFF grants provided to Torres Strait Islander communities have helped them to purchase equipment, such as portable freezers, outboards, dinghies and other fishing gear; this is likely to have positively affected profitability for the TIB Sector (AFMA, 2015, pers. comm.)

16.4 Environmental status

The TSFF is included on the List of Exempt Native Specimens under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and has export approval until 22 December 2017.

No ecological risk assessments have been conducted for the TSFF. The strategic assessment report (AFMA 2012) assumes that the impacts of fishing on the ecosystem are restricted to anchoring, mooring and other anthropogenic activities; vessel accidents, leading to pollution such as oil spills; and potential translocation of species via hull and anchor fouling. The report concludes that direct impacts on the environment are likely to be minimal because of the low-impact nature of the hook-and-line fishing methods used in the fishery.

AFMA publishes quarterly logbook reports of interactions with protected species on its website. No interactions with species protected under the EPBC Act were reported in the TSFF in 2016.

16.5 References

AFMA 2005, Torres Strait finfish bycatch action plan 2005, Australian Fisheries Management Authority, Canberra.

—— 2012, Strategic assessment report: Torres Strait Finfish Fishery, AFMA, Canberra.

—— 2016, ‘Torres Strait Scientific Technical Finfish Working Group: meeting record, 10 November 2016, Brisbane', available at http://pzja.gov.au/wp-content/uploads/2017/03/Finfish-Scientific-Technical-Working-Group-10-Nov-16-Final-Meeting-Record.pdf.

Begg, GA, Chen, CCM, O'Neill, MF & Rose, DB 2006, Stock assessment of the Torres Strait Spanish Mackerel Fishery, technical report 66, CRC Reef Research Centre, Townsville.

Buckworth, RC, Newman, SJ, Ovenden, JR, Lester, RJG & McPherson, GR 2007, The stock structure of northern and Western Australian Spanish mackerel, Fisheries Research and Development Corporation project 1998/159, Northern Territory Department of Primary Industry, Fisheries and Mines, Darwin.

Busilacchi, S 2008, ‘The subsistence coral reef fish fishery in the Torres Strait: monitoring protocols and assessment', PhD thesis, James Cook University, Townsville.

——, Williams, AJ, Russ, GR & Begg, GA 2012, ‘The complexity of applying minimum legal sizes (MLS) of retention in an Indigenous coral reef fishery', Fisheries Management and Ecology, vol. 19, pp. 233–44.

——, Russ, GR, Williams, AJ, Begg, GA & Sutton, SG 2013, ‘Quantifying changes in the subsistence reef fishery of Indigenous communities in Torres Strait, Australia', Fisheries Research, vol. 137, pp. 50–8.

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

O'Neill, MF & Tobin, A 2016, Torres Strait Spanish mackerel stock assessment II, 2015, Torres Strait AFMA project number RR2014/0823, Queensland Department of Agriculture and Fisheries, Brisbane.

QDAFF 2013, Coral Reef Fin Fish Fishery: 2011–12 fishing year report, Queensland Department of Agriculture, Fisheries and Forestry, Brisbane.

TSFFWG 2010, ‘Outcomes of TSFMAC 11', TSFFWG papers, Torres Strait Finfish Working Group meeting 2010.1, 31 March 2010, Thursday Island, available at http://pzja.gov.au/pzja-and-committees/torres-strait-finfish-working-group-tsffwg.

TSFMAC 2012, ‘Torres Strait Finfish Working Group meeting 2012.1: combined papers', Torres Strait Fisheries Management Advisory Committee, available at http://pzja.gov.au/wp-content/uploads/2011/07/FFWG-March-2012-Combined-Papers.pdf.

TSRA 2013, Torres Strait Regional Authority annual report 2012–2013, Torres Strait Regional Authority, available at www.tsra.gov.au/__data/assets/pdf_file/0018/5832/tsra-annual-report-2012-2013.pdf.

—— 2015, Torres Strait Regional Authority annual report 2014–2015, TSRA, available at www.tsra.gov.au/__data/assets/pdf_file/0019/9514/AR2014-TSRA-Annual-Report-2014-2015-Final-Published-2-Nov-2015.pdf.

—— 2016, Torres Strait Regional Authority annual report 2015–2016, TSRA, available at www.tsra.gov.au/__data/assets/pdf_file/0011/12035/TSRA-Annual-Report-2015-2016.pdf.

Williams, AJ, Begg, GA, Little, LR, Currey, LM, Ballagh, AC & Murchie, CD 2007, Evaluation of the eastern Torres Strait Reef Line Fishery, Fishing and Fisheries Research Centre, technical report 1, James Cook University, Townsville.

——, Ballagh, AC, Begg, GA, Murchie, CD & Currey, LM 2008, ‘Harvest patterns and effort dynamics of Indigenous and non-Indigenous commercial sectors of the eastern Torres Strait Reef Line Fishery', Continental Shelf Research, vol. 8, pp. 2117–28.

——, Little, LR & Begg, GA 2011, ‘Balancing Indigenous and non-Indigenous commercial objectives in a coral reef finfish fishery', ICES Journal of Marine Science, vol. 68, no. 5, pp. 834–47.

Spanish mackerel
Ashley Williams, ABARES

Chapter 17: Torres Strait Tropical Rock Lobster Fishery

A Williams and K Mazur

FIGURE 17.1 Regional map showing the management area of the Torres Strait Tropical Rock Lobster Fishery
TABLE 17.1 Status of the Torres Strait Tropical Rock Lobster Fishery
Status
Biological status
2015
Fishing mortality
2015
Biomass
2016
Fishing mortality
2016
Biomass
Comments
Tropical rock lobster (Panulirus ornatus)Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedCurrent catches are unlikely to result in biomass falling below the target and limit reference points. Spawning stock biomass is above the target level.

Economic status
NER are likely to have improved in 2015–16. A decrease in effort in the fishery in 2015–16 suggests a reduction in fishing costs and, when combined with a lower fall in gross value of production, indicates that NER in the fishery are likely to have increased. This result has been achieved in the context of other objectives, including positive social and cultural outcomes.

Notes: NER Net economic returns.

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17.1 Description of the fishery

The Torres Strait Tropical Rock Lobster Fishery (TSTRLF) is commercially fished in the Torres Strait Protected Zone (TSPZ) by Australian and Papua New Guinean nationals. Australians hold Transferable Vessel Holder (TVH) licences or Traditional Inhabitant Boat (TIB) licences (see Chapter 15).

Area fished

The TSTRLF extends from Cape York to the northern border of the TSPZ (Figure 17.1). Most catch comes from the western and south-eastern parts of the fishery, where the densities of tropical rock lobster are highest (AFMA 2013). Access to this fishery is shared by Australia and Papua New Guinea (PNG) under formal arrangements in the Torres Strait Treaty (see Chapter 15).

Fishing methods and key species

The TSTRLF is based on a single species: tropical rock lobster (Panulirus ornatus). It is predominantly a dive-based, hand-collection fishery. Divers use surface-supplied air (hookah) or free-dive, and work from 4–6 metre tenders (one diver per tender). Some lobsters are also collected at night on shallow reef flats by fishers using a light and handheld spear or scoop net.

The TVH Sector uses motherships (large catch-storage vessels) in conjunction with smaller fishing tenders, generally using hookah gear. A small fleet of 12 TVH vessels undertake trips to fishing grounds and fish for a few days to several weeks. In contrast, most fishing trips in the TIB Sector last for only a day or two, with divers working from smaller boats that depart from their local island communities. In recent years, however, an increasing number of TIB Sector operators have used motherships in conjunction with fishing tenders and hookah equipment. This has allowed TIB Sector operators to target live rock lobster, which attracts a higher and more consistent market price than frozen rock lobster tails.

Management methods

The TSTRLF is currently managed primarily through effort restrictions (input controls). In 2016, the Protected Zone Joint Authority (PZJA) released a draft management plan, the Torres Strait Fishery (Quotas for Tropical Rock Lobster [Kaiar]) Management Plan 2016, for public comment. The draft plan proposes the introduction of a quota-based allocation system (output controls) based on catch history between 1997 and 2001, with provisions for leasing quota. The draft plan is not in force.

As part of the transition planning, the Tropical Rock Lobster Resource Assessment Group (TRLRAG) is developing a harvest strategy for the TSTRLF, and fishery-specific target and limit reference points are being defined. The interim harvest strategy uses a limit reference point for biomass (32 per cent of spawning biomass in 1973 [SB1973]—0.32SB1973), a trigger reference point for biomass (0.48SB1973), a target reference point for biomass (0.65SB1973) and a target reference point for fishing mortality rate (FTARG = 0.15). The proposed harvest control rule uses a constant exploitation rate (FTARG = 0.15 per year) while the stock size is at or above the trigger reference point for biomass. The exploitation rate then decreases linearly to zero as the spawning biomass decreases from the trigger to the limit reference point. The interim harvest strategy is used to determine a nominal (non-binding) total allowable catch (TAC). However, since the TAC is currently non-binding, it is not used to control harvest.

Allocations for the TVH, TIB and PNG sectors have been based on agreed shares of the non-binding TAC recommended for the TSPZ by the TRLRAG each year. For the 2015–16 fishing season, shares for the three commercial fishing sectors were approximately 29 per cent for the TVH Sector, 38 per cent for the TIB Sector and 33 per cent for PNG.

The input controls that currently apply to the TSTRLF include a limited commercial fishing season (from 1 December to 30 September); a ban on the use of hookah gear between 1 October and 31 January, and around some new and full moon periods; minimum size limits for commercially caught lobsters of 90 mm carapace length or 115 mm tail length; collection of lobsters only by hand or by handheld implements such as snares, nets or spears; and a prohibition on the possession of tropical rock lobster meat that has been removed from any part of a tropical rock lobster, on any boat, unless that lobster was taken in the course of traditional fishing.

Fishing effort

Fishing effort in the TSTRLF is reported as tender-days, which is the common unit of effort across all sectors. Reported fishing effort (available since 1994), in tender-days, for the TVH Sector reached a peak of 5,200 in 2003–04 before decreasing to approximately 1,300 in 2008–09. Effort then increased to 3,008 tender-days in 2012–13 before decreasing to 2,604 in 2015–16 (Table 17.2). Fishing effort in the TIB Sector has been more difficult to estimate because of under-reporting and duplication in the docket book system used to collect catch-and-effort data. Analyses of the TIB effort data (available since 2004) that adjust for under-reporting and remove duplicate records (Campbell 2017) indicate that effort, in tender-days, has decreased from more than 9,000 in 2004–05 to the lowest level of 2,619 in 2012–13. Since then, effort in tender-days has increased to 5,852 in 2014–15 and 5,359 in 2015–16. Fishing effort for the PNG sector in Australian waters has decreased from a peak of more than 2,200 tender-days in 2009–10, and has been zero since 2013–14.

TABLE 17.2 Main features and statistics for the TSTRLF
Fishery statistics a 2014–15 fishing season2014–15 fishing season2014–15 fishing season2015–16 fishing season2015–16 fishing season2015–16 fishing season
Stock TAC
(t)
Catch
(t)
Real value (2014–15)
TAC
(t)
Catch
(t) b
Real value
(2015–16)
Australia (TVH, TIB)515
(226, 289)
327
(153, 174)
$14.5 million534
(234, 300)
445
(238, 207)
$14.3 million
PNG 254236na262127na
Total fishery 769 563 na 796 572 na


Fishery-level statistics
2014–15 fishing season2015–16 fishing season
Effort cTVH: 2,682 tender-days, 1,173 operation-days
TIB: 5,852 tender-days
PNG: 0 tender-days (in Australian waters)
TVH: 2,604 tender-days, 1,146 operation-days
TIB: 5,359 tender-days
PNG: 0 tender-days (in Australian waters)
Fishing permitsTVH: 12 licences, 33 tenders
TIB: 294
PNG: 0 PNG cross-endorsed; hundreds of PNG dinghies and canoes fish from coastal villages in PNG waters
TVH: 12 licences, 33 tenders
TIB: 294
PNG: 0 PNG cross-endorsed; hundreds of PNG dinghies and canoes fish from coastal villages in PNG waters
Active vesselsTVH: 11
TIB: 294
PNG: 0 (cross-endorsed)
TVH: 11
TIB: 294
PNG: 0 (cross-endorsed)
Observer coverage00
Fishing methodsHandheld implements (snare, net or spear) on shallow reef flats at night; free-diving or use of hookah gear during the dayHandheld implements (snare, net or spear) on shallow reef flats at night; free-diving or use of hookah gear during the day
Primary landing portsThursday Island, Cairns (Queensland); Daru (PNG)Thursday Island, Cairns (Queensland); Daru (PNG)
Management methodsInput controls: gear controls, seasonal and lunar closures
Output controls: minimum size limit (>115 mm tail length or >90 mm carapace length), bag limit of 3 lobsters per person (or 6 lobsters per dinghy if more than one person aboard the boat) for traditional and recreational fishing
Input controls: gear controls, seasonal and lunar closures
Output controls: minimum size limit (>115 mm tail length or >90 mm carapace length), bag limit of 3 lobsters per person (or 6 lobsters per dinghy if more than one person aboard the boat) for traditional and recreational fishing
Primary marketsDomestic: live lobsters and frozen tails
International: United States (frozen tails), Hong Kong/China (live lobsters)
Domestic: live lobsters and frozen tails
International: United States (frozen tails), Hong Kong/China (live lobsters)
Management planNoneNone

a Fishery statistics are provided by fishing season, unless otherwise indicated. Fishing season is 1 December to 30 September. Real-value statistics are by financial year. b Estimate at time of publishing; this figure is preliminary and likely to be updated in future editions of this publication. c Tender-day is a day of fishing effort using a fishing tender or dory.
Notes: na Not available. PNG Papua New Guinea. TAC Total allowable catch. TIB Traditional Inhabitant Boat. TVH Transferable Vessel Holder.

17.2 Biological status

Tropical rock lobster (Panulirus ornatus)

Tropical rock lobster (Panulirus ornatus) 

Line drawing: Karina Hansen

Stock structure

Although postlarval-stage lobsters are locally resident, tropical rock lobster populations in Torres Strait (managed under the PZJA), the Coral Sea (managed by the Commonwealth) and Queensland (managed by Queensland) are considered to comprise a single biological stock as a result of the mixing of larvae in the Coral Sea (Pitcher et al. 2005). Assessments presented here relate specifically to the stock resident in Torres Strait.

Catch history

Total catch of tropical rock lobster since 1978 has fluctuated between 121 and 911 t per year for the Australian sectors (TVH and TIB) and 69 and 686 t for PNG (Figure 17.2). Average catches over the past five years were 442 t for the Australian sectors and 181 t for PNG.

FIGURE 17.2 Catch and TAC of tropical rock lobster in the TSTRLF, 1978 to 2016
Note: TAC Total allowable catch.
Source: Torres Strait Protected Zone Joint Authority, Australian Fisheries Management Authority
Stock assessment

The statistical catch-at-age model developed by Plagányi et al. (2009) was used for the 2016 assessment (Plagányi et al. 2017). The assessment used a time series of catch data from 1973 to 2016, and incorporates annual fishery-independent preseason survey (2005 to 2008, and 2014 to 2016) and mid-season (1989 to 2014) survey data, and catch-per-unit-effort data from the TVH (1994 to 2016) and TIB (2004 to 2016) sectors (Plagányi et al. 2017).

The assessment estimated the 2016 spawning biomass to be 5,877 t (90 per cent confidence interval 3,671 to 8,083 t), or 119 per cent of the estimated unfished (1973) level (1.19SB1973) (Plagányi et al. 2017). Estimates of maximum sustainable yield (MSY)–based parameters are considered to be uncertain because of highly variable annual recruitment and a limited number of age classes in the fishery. For such recruitment-driven fisheries, annual yields can be expected to fluctuate widely about deterministic quantities such as MSY. The (non-binding) TAC is calculated each year based on the target fishing mortality rate of 0.15 (FTARG), which is estimated to keep the biomass at roughly current levels. For 2016, the TRLRAG recommended a non-binding TAC of 796 t, of which 572 t was caught (Table 17.2). The recommended non-binding TAC for 2017 is 495 t, based on the outputs from the reference case assessment model (Plagányi et al. 2017). The recommended 2017 TAC is lower than for previous years because of the low densities of recruits observed in 2016 and subsequent model predictions that the spawning biomass in 2017 will drop to 63 per cent of unfished levels (0.63SB1973).

Stock status determination

The model-estimated biomass in 2016 (1.19SB1973) was well above the target (0.65SB1973) and limit (0.32SB1973) reference points. As a result, this stock is classified as not overfished. The total catch of 572 t in 2016 was lower than the non-binding TAC of 796 t, and equated to a fishing mortality of 0.1, which is lower than the target reference point of 0.15. Therefore, the stock is classified as not subject to overfishing.

17.3 Economic status

Key economic trends

Catch in the fishery is landed as either whole lobster or lobster tails, with whole lobsters generally being landed live. All catch and value figures discussed here have been converted to whole weight to allow comparisons of catch composition.

Landed catch in the fishery decreased by 1 per cent in the 2015–16 financial year, from 381 t in 2014–15 to 376 t in 2015–16 (Figure 17.3).2 The quantity of whole lobster increased from 275 t (whole-weight equivalent) in 2014–15 to 293 t (whole-weight equivalent) in 2015–16. The quantity of tails landed in 2015–16 decreased by 22 per cent (to 82 t [whole-weight equivalent]) compared with the previous year. Effort in the TIB Sector of the fishery declined by 8 per cent between the 2014–15 fishing season (5,852 tender-days) and the 2015–16 fishing season (5,359 tender-days). The commercial fishing season runs from 1 December to 30 September and so spans financial years (Table 17.2).

The gross value of production (GVP) of the Australian fishery (not including PNG) decreased by 1 per cent, from $14.5 million in 2014–15 to $14.3 million in 2015–16 (Figure 17.4). Because less tails were landed, the value of rock lobster tails decreased by 23 per cent, from $1.5 million in 2014–15 to $1.1 million in 2015–16. The decline in effort over the same period suggests a reduction in fishing costs and, when combined with the lower fall in GVP, indicates that net economic returns to the fishery are likely to have increased.

FIGURE 17.3 Production volumes of whole lobster and lobster tails in Torres Strait (for the Australian sectors), 2005–06 to 2015–16
Notes: Lobster tail production has been converted to whole weight.
FIGURE 17.4 Real GVP and price for whole lobster and lobster tails (whole-weight equivalent) in the TSTRLF, 2005–06 to 2015–16
Note: GVP Gross value of production.

A management strategy evaluation (MSE) for the TSTRLF was completed in 2012 (Plagányi et al. 2012). The MSE tested a range of management strategies and fishery scenarios, taking into account biological, economic, cultural and social factors. It included a bio-economic model that estimated subsector profit using data collected from fishers, processors and catch logbooks (Hutton et al. 2016). The analysis assumed four subsectors: a full-time, largely non-Indigenous commercial TVH subsector; a full-time commercial TIB subsector (which includes TIB fishers who catch more than 1,000 kg per year); a part-time semicommercial TIB subsector (TIB fishers who catch 50–1,000 kg per year); and a ‘casual' TIB subsector (TIB fishers who catch less than 50 kg per year).

The MSE-generated, model-based scenario estimates of average profit for the subsectors take into account the high variability in characteristics of the mothership fleet. These estimates are calculated per calendar year in the final model run for each management strategy and scenario combination. Profitability3 was estimated to vary substantially between fleets, with the TVH subsector being the most profitable. The average TVH boat (representing a mothership) was estimated to earn $675,000 in revenue and $269,000 in profit. This equated to an estimated profit for the entire TVH fleet of about $3 million (note that these figures are not survey-based estimates as discussed for other fisheries surveyed by ABARES). For the TIB subsectors, model-based estimates of profit were only determined for the full-time commercial TIB subsector, for which profit per boat was estimated at $25,000 and total fleet profit was estimated at $1.1 million. For the remaining TIB subsectors, economic returns to owner–operator labour were determined to be a more relevant measure of economic performance, given the livelihood focus of TIB operators and the fact that economic performance reflects the earnings of owner–operators from their input into the fishing business. The sum of commercial profit (TVH Sector) and returns to owner–operators in the TIB Sector was estimated at around $6 million.

Management arrangements

The fishery is currently managed under input controls, including seasonal closures, temporal restrictions on the use of hookah equipment and minimum size limits (Table 17.2; AFMA, 2013, pers. comm.; PZJA 2015). A voluntary buyout of fishing licences for non–Traditional Inhabitants commenced in 2011, aimed at increasing the ownership and participation of Traditional Inhabitants in the fishery (PZJA 2013a). The buyback, through an open tender process, resulted in a 2 per cent increase in the Traditional Inhabitants' share of fishery catch, to 56.2 per cent of the Australian share (PZJA 2013a). The buyback was completed in 2012, with the PZJA committed to developing a management plan for the fishery that ensures the sustainability of the resource. The PZJA is currently considering the next steps in view of the buyback outcome (PZJA 2013b), but has acknowledged and agreed to support the aspiration of 100 per cent ownership of Torres Strait fisheries by Torres Strait Islander and Aboriginal traditional owners (PZJA 2014).

The MSE results of the three potential management options predicted that an individual transferable quota (ITQ) system is unlikely to achieve the aim of increasing the TIB share of total Australian catch in the fishery to 70 per cent (Pascoe et al. 2012). Monitoring in the TIB Sector is difficult because of its small scale, and an ITQ system requires a substantial investment in science and accurate reporting of catches (van Putten et al. 2013). Pascoe et al. (2012) noted that a competitive quota arrangement for the TIB fleet might limit the benefits of quota management if there is a race to fish, although effort in the TIB Sector remains well below the sector's nominal allocation. They discussed a community-based arrangement as a potential option. However, van Putten et al. (2013) noted that this type of arrangement is associated with several challenges, including concerns about potentially undermining the supply chain that all fishers rely on, and concerns about maintaining the principles of equity and continued community access to the resource.

Performance against economic objective

Like other Torres Strait fisheries, the TSTRLF is managed against objectives that differ from those of solely Australian Government–managed fisheries. The TSTRLF management objectives are relevant to economic performance, but have a broader focus on social and cultural factors. They include the objectives of (PZJA 2015):

  • maintaining the fishing mortality at a level below the level that produces MSY (FMSY), accounting for all sources of fishing mortality
  • in accordance with the Torres Strait Treaty, protecting the traditional way of life and livelihood of Traditional Inhabitants, particularly in relation to their traditional fishing for tropical rock lobster
  • providing for optimal utilisation, cooperative management with Queensland and PNG, and catch sharing with PNG
  • monitoring interactions between the prawn and lobster fisheries
  • maintaining appropriate controls on fishing gear allowed in the fishery, to minimise impacts on the environment
  • promoting economic development in the Torres Strait area, with an emphasis on providing the framework for commercial opportunities for Traditional Inhabitants, and ensuring that the opportunities available to all stakeholders are socially and culturally appropriate for Torres Strait, and the wider Queensland and Australian community
  • optimising the value of the fishery.

17.4 Environmental status

The TSTRLF is included in the List of Exempt Native Specimens under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and is exempt from export controls until 27 October 2017.

The fishery has little direct impact on the marine environment or other fish species, since hand-collection fishing methods allow careful selection of catch. The level 1 ecological risk assessment did not identify any species at medium or high risk, and found that interactions with protected species were negligible or low because of the nature of the fishery (Furlani et al. 2007). Therefore, no further risk assessments were undertaken (AFMA 2009).

The Australian Fisheries Management Authority publishes quarterly summaries of logbook reports of interactions with protected species on its website. No interactions with species protected under the EPBC Act were reported in the TSTRLF in 2016.

17.5 References

AFMA 2009, Ecological risk management report for the Torres Strait Tropical Rock Lobster Fishery, Australian Fisheries Management Authority, Canberra.

—— 2013, Torres Strait Tropical Rock Lobster Fishery 2013, annual report, AFMA, Canberra.

Campbell, R 2017, Estimation of total annual effort in the Torres Strait Rock Lobster Fishery, CSIRO Oceans and Atmosphere Flagship, Hobart.

Furlani, D, Dennis, D, Dowdney, J, Butler, A & Mason, F 2007, Ecological risk assessment for the effects of fishing: report for the Torres Strait Rock Lobster Fishery, report for AFMA, Canberra.

Hutton, T, van Putten, IE, Pascoe, S, Deng, RA, Plagányi, E & Dennis, D 2016, ‘Trade-offs in transitions between artisanal and commercial fishing sectors: the Torres Strait Tropical Rock Lobster Fishery', Fisheries Management and Ecology, vol. 23, no. 6, pp. 463–77.

Pascoe, S, Hutton, T, van Putten, I, Dennis, D, Skewes, T, Plagányi, É & Deng, R 2012, ‘Estimating fleet size changes when modelling the introduction of rights based management: the case of the Torres Strait Rock Lobster Fishery', in ÉE Plagányi, R Deng, D Dennis, T Hutton, S Pascoe, I van Putten & T Skewes (eds), An integrated management strategy evaluation (MSE) for the Torres Strait Tropical Rock Lobster, Panulirus ornatus Fishery, AFMA & CSIRO draft final project report, AFMA project 2009/839, CSIRO, Cleveland, Queensland.

Pitcher, CR, Turnbull, CT, Atfield, J, Griffin, D, Dennis, D & Skewes, T 2005, Biology, larval transport modelling and commercial logbook data analysis to support management of the NE Queensland rocklobster Panulirus ornatus fishery, Fisheries Research and Development Corporation project 2002/008, CSIRO Marine Research, Brisbane.

Plagányi, ÉE, Dennis, D, Kienzle, M, Ye, Y, Haywood, M, Mcleod, I, Wassenberg, T, Pillans, R, Dell, Q, Coman, G, Tonks, M & Murphy, N 2009, TAC estimation & relative lobster abundance surveys 2008/09, AFMA project 2008/837, CSIRO, Cleveland, Queensland.

——, Deng, R, Dennis, D, Hutton, T, Pascoe, S, van Putten, I & Skewes, T (eds) 2012, An integrated management strategy evaluation (MSE) for the Torres Strait Tropical Rock Lobster Panulirus ornatus Fishery, AFMA & CSIRO draft final project report, AFMA project 2009/839, CSIRO, Cleveland, Queensland.

——, Dennis, D, Campbell, R, Tonks, M, Haywood, M, Deng, R, Murphy, N & Salee, K 2017, Torres Strait rock lobster (TRL) fishery surveys and stock assessment, March 2017 progress report, AFMA project 2016/0822, CSIRO Oceans and Atmosphere, Brisbane.

PZJA 2013a, ‘Tropical rock lobster fishery—voluntary buyback complete', Protected Zone Joint Authority, Canberra, http://pzja.gov.au/2013/01/tropical-rock-lobster-fishery-voluntary-buyback-complete.

—— 2013b, ‘Torres Strait Tropical Rock Lobster Resource Assessment Group (TRLRAG) meeting 12, 3–4 September 2013', draft minutes, PZJA, Canberra.

—— 2014, ‘PZJA meeting 23, 8–9 April 2014', PZJA, Canberra, http://pzja.gov.au/pzja-and-committees/protected-zone-joint-authority-pzja/pzja-meeting-23-8-9-april-2014.

—— 2015, ‘Torres Strait Tropical Rock Lobster Fishery', PZJA, Canberra, http://pzja.gov.au/the-fisheries/torres-strait-tropical-rock-lobster-fishery.

van Putten, I, Deng, R, Dennis, D, Hutton, T, Pascoe, S, Plagányi, É & Skewes, T 2013, ‘The quandary of quota management in the Torres Strait Rock Lobster Fishery', Fisheries Management and Ecology, vol. 20, no. 4, pp. 326–37.

Footnotes

2Catch weights and gross value of production in this section are given by financial year.

3In bio-economic assessments that are part of an MSE, estimates of profit and returns to owner–operators are based on summing average values (whereas individual operations vary considerably); these indices are used as output performance indices to check for relative differences between scenarios.

Tropical rock lobsters
Department of Agriculture and Water Resources

Chapter 18: Torres Strait Prawn Fishery

A Williams and K Mazur

FIGURE 18.1 Relative fishing intensity in the Torres Strait Prawn Fishery, 2016
TABLE 18.1 Status of the Torres Strait Prawn Fishery
Status
Biological status
2015
Fishing mortality
2015
Biomass
2016
Fishing mortality
2016
Biomass
Comments
Brown tiger prawn (Penaeus esculentus)Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedCatch in recent years is below MSY. Most recent estimate of biomass is above BMSY.
Blue endeavour prawn (Metapenaeus endeavouri)Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedCatch in recent years is below MSY. Most recent estimate of biomass is above BMSY.

Economic status
NER for the fishery were negative in 2012–13 (–$2.3 million); no estimates of NER are available for 2014–15 and 2015–16, although a significant increase in gross value of production in 2014–15 and 2015–16 relative to 2012–13 suggests improvement in NER.

Notes: BMSY Biomass at maximum sustainable yield. MSY Maximum sustainable yield. NER Net economic returns.

Prawn trawling gear
AFMA

[expand all]

18.1 Description of the fishery

Area fished

The Torres Strait Prawn Fishery (TSPF) operates in the eastern part of the Torres Strait Protected Zone (TSPZ) and south of the TSPZ in nearby Queensland waters (called the ‘outside but near area') (Figure 18.1). This fishery is shared by Australia and Papua New Guinea (PNG) under formal arrangements in the Torres Strait Treaty (see Chapter 15).

Fishing methods and key species

Prawns are harvested at night using demersal otter trawl (prawn trawl). Fishers usually deploy four nets divided into two pairs, with a pair of nets towed from a boom on each side of the fishing vessel. Trawl tows last between two and a half and four hours at an average speed of around 3 knots. Fishers normally complete three or four tows per night (DSEWPaC 2013; Turnbull et al. 2007).

The target species of the fishery are brown tiger prawn (Penaeus esculentus) and blue endeavour prawn (Metapenaeus endeavouri). Byproduct species include redspot king prawn (Melicertus longistylus),4slipper lobster (Scyllarides spp.), Moreton Bay bugs (Thenus spp.), octopus (Octopodidae), cuttlefish (Sepia spp.) and squid (Teuthoidea).

Management methods

The Australian component of the fishery is managed by the Torres Strait Protected Zone Joint Authority (PZJA), established under the Torres Strait Fisheries Act 1984 (Cwlth). Currently, all licences in the fishery are held by the non-Indigenous Transferable Vessel Holder (TVH) Sector.

Under the Torres Strait Treaty, PNG is entitled to 25 per cent of the TSPF resource in the Australian jurisdiction (excluding the effort in nearby Queensland waters), and Australia is entitled to 25 per cent of the TSPF resource in the PNG jurisdiction (Cocking 2016). Historically, some Australian boats fished in PNG waters, but this ceased soon after ratification of the Torres Strait Treaty. There is no official record of PNG boats fishing in Australian waters, and PNG operators have only sporadically activated their entitlements to fish in their own waters of the TSPZ.

The fishery is subject to several spatial and temporal closures (Figure 18.1) that were initiated for various reasons, including protection of undersized tiger prawns (those that are below commercially marketable sizes; Watson & Mellors 1990), protection of pearl shell beds and protection of breeding populations of marine turtles.

The PZJA released a harvest strategy for the TSPF in 2011 (AFMA 2011), which defines a set of trigger, target and limit reference points, and decision rules for the whole fishery, based on the most sensitive target species—tiger prawn. A catch trigger also exists for endeavour prawn. Triggers are set at levels that acknowledge the reduced effort in the fishery in recent years, and the harvest strategy provides for revision and update to the trigger levels if activity in the fishery increases. The strategy incorporates a long-term economic target that will be pursued once catch-and-effort triggers in the fishery are reached. A short-term economic target is not in place because the fishery does not currently have the resources to estimate biomass at maximum economic yield (BMEY). Also, since a BMEY target would reduce fishing effort, there is concern that reducing the available fishing days to achieve a proxy economic target would put additional economic pressure on operators who are fishing, when effort is already well below target levels.

The harvest strategy's limit reference point is 20 per cent of unfished biomass (0.2B0), consistent with the default provided for in the Commonwealth Fisheries Harvest Strategy Policy (HSP; DAFF 2007). The current target reference point (BTARG) is based on the maximum sustainable yield (MSY) of the most sensitive of the target species—tiger prawn—so that BTARG = BMSY. In contrast, the triggers in this fishery are aligned with the concept of MEY, consistent with the fishery's goal to move to MEY-based targets when fishing activity increases. The triggers are based on fishers catching 75 per cent of Australia's portion of total allowable catch (or expending 75 per cent of Australia's portion of the total allowable effort [TAE]). The proxy used for BMEY is 1.2BMSY, equating to 0.34B0 where BMSY = 0.28B0.

Fishing effort

From 1999 to 2011, fishing effort in the TSPF decreased steadily from more than 10,000 days to less than 1,500 days, largely as a result of economic conditions in the fishery (Figure 18.2). Effort since 2011 has averaged around 2,000 fishing days per year, but increased to 2,993 days in 2015 and 2,248 days in 2016. The 2016 effort (2,248 days) represents 32.7 per cent of the TAE for the Australian fishery.5

Catch

In addition to brown tiger prawn and blue endeavour prawn, king prawns (Melicertus longistylus, M. latisulcatus and M. plebejus) have also been a historically important component of the catch in the fishery. The total combined catch of brown tiger prawn, blue endeavour prawn and king prawn decreased from a historical high of more than 2,000 t in 1999 to less than 300 t in 2011 (Figure 18.2). Since 2011, the total combined catch has increased steadily with increasing effort, peaking at more than 720 t in 2015 (Figure 18.2; Table 18.2). The proportion of brown tiger prawn in the total catch has increased from below 30 per cent in 1999 to more than 70 per cent in each year since 2010, and was 85 per cent in 2016.

FIGURE 18.2 Prawn catch by species, and fishing effort, in the TSPF, 1989 to 2016
TABLE 18.2 Main features and statistics for the TSPF
Fishery statistics a 201520152015201620162016
Stock TAC
(t)
Catch
(t)
Real value (2014–15)
TAC
(t)
Catch
(t) b
Real value
(2015–16)
Brown tiger prawn560$8.2 million362$7.3 million
Blue endeavour prawn166$0.9 million56$1.0 million
Total fishery 742 b $9.5 million c 412 b $8.9 million c

Fishery-level statistics 20152016
Effort (days)2,9932,248
Fishing permits60 (15 inactive licences not attached to vessels)60 (38 inactive licences)
Active vessels2422
Observer coverage59 days (2% of active effort)34 days (3% of active effort)
Fishing methodsDemersal otter trawlDemersal otter trawl
Primary landing portsCairns, Innisfail (Queensland)Cairns, Innisfail (Queensland)
Management methodsInput controls: total allowable effort on fishing nights, individual transferable effort units, limited entry (although licences are transferable), gear restrictions, time and area closures, vessel length restrictionsInput controls: total allowable effort on fishing nights, individual transferable effort units, limited entry (although licences are transferable), gear restrictions, time and area closures, vessel length restrictions
Primary marketsDomestic: frozen
International: minor to Japan—frozen
Domestic: frozen
International: minor to Japan—frozen
Management plan Torres Strait Prawn Fishery Management Plan 2009 Torres Strait Prawn Fishery Management Plan 2009

a Fishery statistics are provided by fishing season, unless otherwise indicated. Fishing season since 2016 is from 1 February to 1 December. Fishing season before 2016 was from 1 March to 1 December. Real-value statistics are provided by financial year. b Total fishery catch includes the catch of brown tiger, endeavour and king prawns only. c Includes non-prawn byproduct species.
Notes: TAC Total allowable catch. – Not applicable.

18.2 Biological status

Brown tiger prawn (Penaeus esculentus)

Brown tiger prawn (Penaeus esculentus) 

Line drawing: FAO

Stock structure

Brown tiger prawn is endemic to tropical and subtropical waters of Australia. There is evidence of genetic separation of brown tiger prawns from the east and west coasts of Australia (Ward et al. 2006); however, the stock structure across northern Australia is uncertain. Brown tiger prawns are considered to constitute a single stock in Torres Strait for assessment and management purposes.

Catch history

Catch of brown tiger prawn has fluctuated over time, peaking in 1998 at 965 t. Catch decreased to 204 t in 2011 but has since increased, reaching 560 t in 2015 and 362 t in 2016 (Figure 18.3).

FIGURE 18.3 Brown tiger prawn catch in the TSPF, 1989 to 2016
Source: Australian Fisheries Management Authority
Stock assessment

The most recent stock assessment of brown tiger prawn in Torres Strait was completed in 2006 using data to the end of 2003 (O'Neill & Turnbull 2006). Since the 2006 assessment, further assessment model runs with updated data have been conducted (Turnbull & Rose 2007), but no full assessments have been undertaken. The most recent model runs (Turnbull & Rose 2007) indicate that tiger prawn biomass steadily increased from 2000 to 2006, and was between 60 and 80 per cent of the unfished (1980) biomass (0.6B0 and 0.8B0). This was considerably higher than estimates of BMSY, which were 0.28B0 to 0.38B0, depending on the spawner–recruitment relationship used (O'Neill & Turnbull 2006). A delay-difference model (O'Neill & Turnbull 2006) estimated MSY for tiger prawns to be 606 t (90 per cent confidence interval [CI] 436 to 722 t), and effort at MSY (EMSY) to be 8,245 fishing nights6 (90 per cent CI 5,932 to 9,823 nights) using the Ricker spawner–recruitment relationship. Using the Beverton–Holt spawner–recruitment relationship, MSY was estimated to be 676 t (90 per cent CI 523 to 899 t) and EMSY to be 9,197 nights (90 per cent CI 7,116 to 12,231 nights).

The 2006 assessment is still used to inform management decisions in the fishery. However, brown tiger prawn is a relatively short-lived species, with variable recruitment that can be influenced by environmental factors. Changes in fleet dynamics and vessel efficiency are also likely to influence the long-term relevance of the 2006 assessment, as are increases in catch and effort since 2011. As a result, the outputs from the 2006 stock assessment will become less relevant over time. Mediating this risk is the substantial underuse of fishing effort, with less than 50 per cent of available fishing nights being used each year since 2008, and annual catches remaining below the 2006 mean estimate of MSY since 2005 (Figure 18.3). In addition, the harvest strategy for the fishery (AFMA 2011) imposes conservative trigger points—set at 4,000 days and 680 t of tiger prawn, which corresponds to approximately 75 per cent of the Australian portion of the estimated effort and catch at B34 (BMEY), respectively. When these trigger points are reached, additional research, a revised harvest strategy to develop decision rules for setting the TAE based on BMEY, and an updated stock assessment are required. Although increasing since 2011, catch and effort in the fishery remain below the trigger points.

Stock status determination

Assessment of brown tiger prawn status in 2016 is based on a comparison of recent catches (Figure 18.3) with estimates of MSY from the 2006 assessment (O'Neill & Turnbull 2006), a comparison of recent effort with estimates of EMSY from the 2006 assessment (O'Neill & Turnbull 2006) and the 2006 estimates of biomass (Turnbull & Rose 2007).

The tiger prawn catch has been below the 2006 estimates of MSY for both Ricker (606 t) and Beverton–Holt (676 t) spawner–recruitment relationships since 2005. The effort in the fishery has been below the 2006 estimates of EMSY for the Beverton–Holt (9,197 nights) and Ricker (8,245 nights) spawner–recruitment relationships since 2003 and 2004, respectively. As a result, the stock is classified as not subject to overfishing.

Although the HSP does not apply to the jointly managed TSPF, the default HSP proxy limit of 0.2B0 is used to inform status evaluations. The 2006 estimate of tiger prawn biomass (between 0.6B0 and 0.8B0) was considerably higher than the estimate of BMSY and well above the HSP proxy limit reference point of 0.2B0. However, uncertainty around the current level of biomass is increasing with time since the most recent stock assessment. Since biomass was well above the limit reference point and BMSY in 2006, and fishing effort has been below the estimated EMSY for at least 13 years, the stock is classified as not overfished.

Blue endeavour prawn (Metapenaeus endeavouri)

Blue endeavour prawn (Metapenaeus endeavouri) 

Line drawing: FAO

Stock structure

Endeavour prawn occurs across northern Australia from Shark Bay in Western Australia to Moreton Bay in Queensland. Little is known about the stock structure of blue endeavour prawns across this region. In Torres Strait, they are considered to constitute a single stock for management and assessment purposes.

Catch history

Annual catches of blue endeavour prawn were relatively high during the 1990s, averaging more than 1,000 t and peaking at more than 1,500 t in 1999 (Figure 18.4). Annual catches have decreased to below 200 t in recent years, and the catch in 2016 was 56 t. This reflects decreasing fishing effort through the 2000s and increased targeting of tiger prawns because of their higher market value (Turnbull 2014).

FIGURE 18.4 Endeavour prawn catch in the TSPF, 1989 to 2016
Source: Australian Fisheries Management Authority
Stock assessment

The most recent stock assessment for blue endeavour prawn was completed in 2009, using data to the end of 2007 (Turnbull et al. 2009). This assessment evaluated abundance of cohorts (annual year-classes) of the stock through time, allowing tracking of size-related variability in productivity.

A deterministic size- and age-structured model with a fixed stock–recruitment steepness value of 0.5 provided an MSY estimate of 1,105 t (90 per cent CI 1,060 to 1,184 t) and an EMSY estimate of 10,079 nights (90 per cent CI 9,667 to 10,800 nights). A stochastic size- and age-structured assessment was also run, but this model did not achieve convergence of parameter estimates and was not accepted. Similarly, a deterministic model with a fixed steepness of 0.7 did not achieve convergence. The biomass estimate from the deterministic model, with steepness fixed at 0.5, was approximately 0.8B0, which is considerably higher than the estimate of 0.43B0 for BMSY.

The 2009 stock assessment is still used to inform management decisions in the fishery. However, similar to brown tiger prawn, the outputs from the 2009 stock assessment for blue endeavour prawn have become less relevant over time, with increased uncertainty in current status due to highly variable recruitment, short life span, changes in fleet dynamics and vessel efficiency, and changes in catch and effort.

Stock status determination

The stock status classification of blue endeavour prawn in 2016 is based on a comparison of recent catches with estimates of MSY from the 2009 assessment, a comparison of recent fishing effort with estimates of EMSY, and the 2009 estimates of biomass. Since 2002, catch has been below the lower 90 per cent CI of estimated MSY (1,060 t), and effort has been below the lower 90 per cent CI of EMSY (9,667 nights). As a result, the stock is classified as not subject to overfishing.

Although the HSP does not apply to the TSPF, in the absence of a prescribed limit reference point for this stock, the default HSP proxy limit reference point of 0.2B0 is used to determine stock status. The 2007 biomass estimate of 0.8B0 is above the estimated BMSY of 0.43B0 and well above the HSP proxy limit reference point of 0.2B0. However, uncertainty around the current level of biomass is increasing with time since the most recent stock assessment. Since fishing effort has been below the estimated EMSY since 2002, the stock is classified as not overfished.

18.3 Economic status

Key economic trends

Economic surveys by ABARES of key Commonwealth fisheries since the early 1990s provide information that allows calculation of net economic returns (NER) and financial performance measures for the TSPF. Figure 18.5 presents the historical data per vessel for gross value of production (GVP), NER and hours trawled between 2005–06 and 2015–16.

Estimates of NER are not available for 2008–09, 2009–10 or from 2012–13 to 2015–16 because economic surveys of the fishery were not done for these years. NER for the TSPF have been negative since 2004–05 (Skirtun et al. 2015). Based on the latest survey in 2013, it was estimated that NER remained negative at –$2.3 million in the 2012–13 financial year, an improvement from –$2.7 million in 2011–12. High input costs and low prices in 2011–12 and 2012–13 made it difficult to operate profitably in the fishery (Skirtun et al. 2015).

A significant increase in GVP in 2014–15 and 2015–16 relative to 2012–13 (the last survey year available) suggest an improvement in NER in these two years. Moreover, these two years coincide with a period of lower diesel fuel input costs and Australian dollar exchange rate relative to 2012–13, both factors that contribute positively to NER.

In 2015–16, GVP in the TSPF was $8.9 million, 48 per cent higher than the GVP recorded for the fishery in 2012–13. Tiger prawn accounted for the largest share of GVP (83 per cent; $7.3 million), followed by endeavour prawn (11 per cent; $1 million) and king prawn (3 per cent; $0.2 million). Other prawn species and other species caught as byproducts accounted for the remainder (3 per cent) of the GVP of the fishery.

Between 2005–06 and 2009–10, the number of hours trawled per vessel almost halved in response to declines in profitability. This is reflected in the GVP per vessel (an indicator of vessel revenue), which followed a declining trend from 2007–08, reaching its lowest level in 2009–10 before increasing significantly to 2015–16 (Figure 18.5). In 2015–16, GVP per vessel increased by 2 per cent to $403,000, and the effort input for the season averaged 1,139 trawl hours per vessel. The effort input per vessel declined slightly (by 1 per cent) in 2015–16.

FIGURE 18.5 GVP, NER and hours trawled per vessel in the TSPF, 2005–06 to 2015–16
Note: GVP Gross value of production. NER Net economic returns.

Management arrangements

The fishery is managed using input controls. Limits on the number of boat licences and tradeable fishing nights are the main input controls, and these are combined with other restrictions on gear and vessel characteristics (Cocking 2016). In their analysis of profit trends in the TSPF, Skirtun and Vieira (2012) suggested that management arrangements in the fishery may have been a constraint on greater productivity gains and, therefore, higher profitability. The recent divergence in trends in economic performance of the Northern Prawn Fishery (NPF) and the TSPF may also be linked to differences in management arrangements. Although both the NPF and the TSPF are managed with input controls, the TSPF is also managed through limits on maximum vessel size (AFMA 2011). This restriction may have constrained autonomous adjustment in the TSPF and, as a result, fishery-level efficiency. High levels of latent effort have remained in the TSPF and are likely to have reduced the incentive to trade in effort entitlements, limiting the movement of effort entitlements to the most efficient fishers. In 2016, 22 of the 60 licences in the fishery were active, resulting in a licence latency of 63 per cent.

The TSPF has limits on maximum vessel size (AFMA 2011). As larger vessels tend to have larger fuel and catch-holding capacities, such vessels can stay at sea longer and are better able to operate in geographically isolated fisheries such as the TSPF. By preventing the use of larger vessels, this management arrangement may be constraining economic performance in the fishery. In recognition of these issues, in early 2011, the Torres Strait Prawn Management Advisory Committee (TSPMAC) recommended trials of alternative fishing gear and vessel size configurations (PZJA 2011). In 2013, the TSPMAC recommended providing supplementary information to the PZJA to be considered with the original decision for the trial to take place (PZJA 2013a). Subsequently, research was commissioned by the Australian Fisheries Management Authority (AFMA) to consider the flow of economic benefits from the prawn fishery to Traditional Inhabitants and local communities (PZJA 2013b). The research identified a number of possible ways to increase the flow of benefits from the TSPF to communities. The TSPMAC has been considering the options and any requirement for further research (PZJA 2016).

Performance against economic objective

The TSPF is managed according to the economic objective of promoting economic efficiency and ensuring the optimal use of the fishery resource, consistent with the principles of ecologically sustainable development and a precautionary approach. Although these objectives are implicitly consistent with maximising economic yields, the harvest strategy for the fishery does not currently have a target biomass level associated with an estimate of MEY (BMEY). This has been attributed to the low economic value of the fishery and the high cost of estimating a BMEY target (AFMA 2011). The BMSY target will remain until decision rules relating to increased fishing activity are activated that will require a BMEY target to be determined and implemented (AFMA 2011).

The biomass levels of brown tiger and blue endeavour prawns are well above BMSY, and so economic performance is currently not constrained by biomass. Although estimates of NER for 2015–16 are not available, a significant improvement in fishery level GVP and GVP per vessel relative to 2012–13, and improvement in the operating environment as a result of lower diesel fuel input costs and a lower Australian dollar exchange rate suggest an improvement in economic performance of the fishery. Despite these positive signs, the high level of licence latency remains a concern for the fishery.

18.4 Environmental status

Prawn trawling is a relatively non-selective fishing method. As a result, a variety of byproduct and bycatch species are caught with the target species. Bycatch typically includes finfish, cephalopods, crabs, lobsters, scallops, sharks and rays. Trawling also has potential impacts on benthic communities and protected species, including turtles, sea snakes and syngnathids (seahorses and pipefish). Research surveys between 2004 and 2006 collected independent data on the weight, composition and distribution of bycatch in the TSPF (Turnbull & Rose 2007). The surveys were in two areas: the main prawn trawling grounds, and adjacent areas that are seasonally or permanently closed to trawling. No major differences were found in the overall composition and abundance of bycatch species between areas that are open, partially closed and entirely closed to trawling. However, there were some differences in the relative proportions of different bycatch species between open and closed areas.

The TSPF is included on the List of Exempt Native Specimens under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and is exempt from export controls until 22 December 2017.

A level 1 (Scale, Intensity, Consequence Analysis) ecological risk assessment has been conducted for the TSPF (Turnbull et al. 2007). The fishery also has a bycatch and discard workplan that was updated in early 2015 (AFMA 2015). Pitcher et al. (2007) provided comprehensive data on the biodiversity of seabed habitats in Torres Strait, cataloguing more than 3,600 species, comprising fishes, crustaceans and other species that make up the benthos. Examination of the likely extent of past effects of trawling on the benthos and bycatch in the TSPZ indicated that trawling has had an effect on the biomass of 21 of the 256 species analysed. Of the 21 species, 9 have shown a negative response, while 12 have shown an increase in biomass in association with trawling. This research was updated using data to 2011, and showed that, because of a substantial reduction in effort and the trawl footprint since 2005, there is little to no sustainability risk to any species at the current levels of fishing effort (Pitcher 2013).

Since the beginning of the 2002 fishing season, the PZJA has required operators in the TSPF to use turtle excluder devices in trawl gear. In 2004, the use of bycatch reduction devices became mandatory. In May 2008, the PZJA also agreed to implement trawl exclusion zones around Deliverance Island, Kerr Islet and Turu Cay (Figure 18.1) to protect important nesting areas for green turtle (Chelonia mydas) and flatback turtle (Natator depressus).

AFMA publishes quarterly summaries of logbook-reported interactions with protected species on its website. In 2016, 636 sea snakes of unknown species were caught in the TSPF, of which 341 were released alive, 9 were dead, 1 was injured and the remaining 285 had an unknown life status. One flatback turtle (Natator depressus), one hawksbill turtle (Eretmochelys imbricata) and two turtles of unknown species were caught; all were released alive. Nine unidentified seahorses or pipefish were caught, eight of which were dead and one of which had an unknown life status. One narrow sawfish (Anoxypristis cuspidata) and one common sawshark (Pristiophorus cirratus) were released alive.

18.5 References

AFMA 2011, Harvest strategy for the Torres Strait Prawn Fishery, Australian Fisheries Management Authority, Canberra.

—— 2015, Torres Strait Prawn Fishery: bycatch and discard workplan 2015–2017, AFMA, Canberra.

Cocking, L 2016, Torres Strait Prawn Fishery handbook, AFMA, Canberra.

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

DSEWPaC 2013, Assessment of the Torres Strait Prawn Fishery, Australian Government Department of Sustainability, Environment, Water, Population and Communities, Canberra.

O'Neill, MF & Turnbull, CT 2006, Stock assessment of the Torres Strait tiger prawn fishery (Penaeus esculentus), Queensland, Department of Primary Industries and Fisheries, Brisbane.

Pitcher, CR 2013, Environmental sustainability assessment update for habitats, assemblages and bycatch species in the Torres Strait Prawn Fishery, Scientific Technical Report, CSIRO, Australia.

——, Haywood, M, Hooper, J, Coles, R, Bartlett, C, Browne, M, Cannard, T, Carini, G, Carter, A, Cheers, S, Chetwynd, D, Colefax, A, Cook, S, Davie, P, Ellis, N, Fellegara, I, Forcey, K, Furey, M, Gledhill, D, Hendriks, P, Jacobsen, I, Jacobson, J, Jones, M, Last, P, Marks, S, McLeod, I, Sheils, J, Sheppard, J, Smith, G, Strickland, C, Van der Geest, C, Venables, W, Wassenberg, T & Yearsley, G 2007, Mapping and characterisation of key biotic and physical attributes of the Torres Strait ecosystem, CSIRO/QM/QDPI CRC Torres Strait Task final report, CSIRO Marine and Atmospheric Research, Cleveland, Queensland.

PZJA 2011, ‘20m boat rule and gear restriction trials in the Torres Strait Prawn Fishery', Protected Zone Joint Authority, Canberra, http://pzja.gov.au/notices-and-announcements/notices-and-announcements/20m-boat-rule-and-gear-restriction-trials-in-the-torres-strait-prawn-fishery.

—— 2013a, ‘Torres Strait Prawn Management Advisory Committee minutes, TSPMAC 14, 16–17 July 2013', PZJA, Canberra.

—— 2013b, ‘Torres Strait Prawn Management Advisory Committee minutes, TSPMAC teleconference, 26 November 2013', PZJA, Canberra.

—— 2016, ‘Torres Strait Prawn Management Advisory Committee minutes, TSPMAC 17, 20 April 2016', PZJA, Canberra, http://pzja.gov.au/pzja-and-committees/torres-strait-prawn-management-advisory-committee-tspmac/torres-strait-prawn-management-advisory-committee-meeting-17.

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

——, Stephan, M, Curtotti, R & Mazur, K 2015, Australian fisheries economic indicators report 2013: financial and economic performance of the Torres Strait Prawn Fishery, ABARES, Canberra.

Turnbull, C 2014, ‘Logbook statistics', in L Cocking & C Turnbull (eds), Torres Strait Prawn Fishery handbook, PZJA, Canberra.

—— & Rose, CL 2007, Towards ecologically sustainable management of the Torres Strait Prawn Fishery, CRC Torres Strait Task T1.5 final report, Queensland Department of Primary Industries and Fisheries, Brisbane.

——, Furlani, D, Bulman, C & Dowdney, J 2007, Ecological risk assessment for the effects of fishing: report for the Torres Strait Prawn Fishery, report to AFMA, Canberra.

——, Tanimoto, M, O'Neill, MF, Campbell, A & Fairweather, CL 2009, Torres Strait spatial management research project 2007–09, final report for DAFF consultancy DAFF83/06, Queensland Department of Employment, Economic Development and Innovation, Brisbane.

Ward, R, Ovenden, J, Meadows, J, Grewe, P & Lehnert, S 2006, ‘Population genetic structure of the brown tiger prawn, Penaeus esculentus, in tropical northern Australia', Marine Biology, vol. 148, no. 3, pp. 599–607.

Watson, RA & Mellors, JE 1990, ‘General introduction', in JE Mellors (ed.), Torres Strait prawn project: a review of research 1986–1988, Queensland Department of Primary Industries Information Series, Queensland Department of Primary Industries, Brisbane.

Footnotes

4Although small volumes of other king prawn species (M. latisulcatus, M. plebejus) are recorded in logbook records, research surveys in Torres Strait suggest that the commercial catch largely consists of a single species for each prawn group—that is, brown tiger prawn (P. esculentus), blue endeavour prawn (M. endeavouri) and redspot king prawn (M. longistylus) (C Turnbull, AFMA consultant, 2015, pers. comm., 23 July).

5The 9,200 days of TAE in the fishery are shared between Australia and PNG, with Australian operators able to access 6,867 fishing days before an option to access unused PNG days is considered by the PZJA (Cocking 2016); 2,070 fishing days are available to PNG operators and 263 days are held in trust by the Australian Government.

6The terms ‘day' and ‘night' are both used in this chapter when discussing fishing effort because effort units are allocated in notional ‘days' (referring to a 24-hour period), but fishing actually occurs at night.

Tiger prawns
AFMA

Chapter 19: Torres Strait Bêche-de-mer and Trochus fisheries

J Woodhams and K Mazur

FIGURE 19.1 Area of the Torres Strait Bêche-de-mer and Trochus fisheries
TABLE 19.1 Status of the Torres Strait Bêche-de-mer and Trochus fisheries
Status
Biological status
2015
Fishing mortality
2015
Biomass
2016
Fishing mortality
2016
Biomass
Comments
Black teatfish
(Holothuria whitmaei)
Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedNo catch in 2016. Recent survey indicates a recovering stock.
Prickly redfish
(Thelenota ananas)
Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedCatch is below TAC. Survey indicates relatively stable densities.
Sandfish
(Holothuria scabra)
UncertainOverfishedUncertainOverfishedUncertain impact of illegal, unreported and unregulated catch in recent years. Most recent full survey (2009) indicated that stock was overfished.
White teatfish
(Holothuria fuscogilva)
Not subject to overfishingNot overfishedNot subject to overfishingNot overfishedCatch is below TAC. Survey indicates relatively stable densities.
Other sea cucumbers (up to 18 species)Not subject to overfishingUncertainNot subject to overfishingUncertainCatch in 2016 is unlikely to constitute overfishing. Uncertain biomass status for a number of species.
Trochus
(Trochus niloticus)
Not subject to overfishingUncertainNot subject to overfishingUncertainNo recorded take in 2016. Uncertain estimates of population size from most recent survey.

Economic status
Estimates of NER are not available. NER are likely to be lower in the 2016 fishing season because of a significant decrease in the catch of valuable species such as black teatfish and prickly redfish, and lower catches of most other species caught in the fishery.

Notes: NER Net economic returns. TAC Total allowable catch.

[expand all]

19.1 Description of the fishery

Area fished

Both the Torres Strait Bêche-de-mer Fishery (TSBDMF) and the Torres Strait Trochus Fishery (TSTF) operate in tidal waters within the Torres Strait Protected Zone (TSPZ) and south of the TSPZ, in the waters defined as the ‘outside but near area' (Figure 19.1; AFMA 2011, 2013).

Bêche-de-mer (sea cucumber) has historically been harvested in the eastern parts of Torres Strait, with most of the catch typically taken from the Great North East Channel, Don Cay, Darnley Island, Cumberland Channel and Great Barrier Reef regions. Western Torres Strait is included in the fishery, but is documented as having naturally low abundance of sea cucumbers (AFMA 2013).

Trochus has not been fished in recent years. In 2005 (a year for which we have a reasonable idea of catch location), most trochus was taken from central-eastern Torres Strait regions, including the Great North East Channel, Darnley Island and Warraber regions (AFMA 2011).

Fishing methods and key species

Historically, the main species of sea cucumber harvested in Torres Strait have been black teatfish (Holothuria whitmaei), prickly redfish (Thelenota ananas), sandfish (H. scabra), white teatfish (H. fuscogilva), surf redfish (Actinopyga mauritiana), deepwater redfish (A. echinites) and blackfish species (Actinopyga spp.). Sea cucumbers are collected by hand, usually while free-diving or reef-top walking. Reef walking occurs at low tide along the reef edges. Diving usually occurs from dinghies, crewed by two or three fishers. Although the depth range of most targeted species is between 0 and 20 m, a ban on hookah (surface-supplied underwater breathing apparatus) and scuba diving limits most fishing effort to a depth of approximately 10 m. Following collection, sea cucumbers are processed for market; typically, this involves gutting, grading, cleaning, boiling, smoking and drying (AFMA 2013).

Trochus (Trochus niloticus) typically occurs on high-energy areas of reefs, on substrates dominated by stony or coral pavements and associated with turf algae (Murphy et al. 2010). Trochus is collected by hand while reef-top walking at low tide, or from reef tops and reef edges while free-diving (without scuba or hookah gear) (AFMA 2011).

No byproduct or bycatch occurs in these fisheries because fishing by hand allows preferred species to be selected. Interactions with protected species are minimal.

Management methods

The TSBDMF is managed using a range of input and output controls. Input controls include limiting participation in the fishery to Traditional Inhabitant Boat (TIB) licence holders. Traditional Inhabitants who wish to fish commercially for sea cucumbers are required to hold a TIB licence and use a boat no longer than 7 m. Collection is limited to hand fishing, including use of non-mechanical handheld devices; use of hookah and scuba gear is prohibited. Output controls include minimum size limits on 10 species; zero total allowable catch (TAC) for sandfish and surf redfish; and TACs for white teatfish (15 t), prickly redfish (20 t) and other sea cucumber species combined (80 t). Torres Strait Islanders are also entitled to take three sea cucumbers per person per day, or six sea cucumbers per dinghy per day, for personal use.

The TSTF is managed using various input and output controls. Input controls include limiting participation in the fishery to TIB licence holders, limiting fishers to vessels of a maximum of 20 m, restricting trochus harvest to hand fishing using non-mechanical devices, and prohibiting the use of hookah and scuba gear. Output controls include minimum (80 mm) and maximum (125 mm) basal diameter size limits, and a TAC of 150 t.

Although the Commonwealth Fisheries Harvest Strategy Policy (HSP; DAFF 2007) does not apply to fisheries jointly managed by the Australian Government and other (domestic or international) management agencies, the HSP does represent the government's preferred approach to management. The Torres Strait Protected Zone Joint Authority (PZJA) has asked its management forums to provide advice on the application of the HSP to Torres Strait fisheries. No formal harvest strategies are in effect in the TSBDMF or the TSTF; however, a formal harvest strategy for the TSBDMF is being developed.

Fishing effort

Effort in the TSBDMF has increased in recent years in response to developmental permits and fishing trials. No catch has been recorded in the TSTF since 2010.

The Papua New Guinea (PNG) Bêche-de-mer Fishery (all species) was closed in 2009. The moratorium on take and/or possession of bêche-de-mer was lifted on 1 April 2017. Quotas set for various provinces were quickly reached, and the Western Province fishery, among others, was again closed by 1 June 2017.

Ongoing monitoring of illegal, unreported and unregulated (IUU) activity, and enforcement action by authorities in Australia and PNG continues, including cooperative patrols and capacity building between the two nations. The IUU catch in PNG waters is unknown.

Catch

Historically, sandfish was a primary target species in the TSBDMF, mostly fished on the Warrior Reef complex (Figure 19.1). Following a considerable decline in sandfish abundance and the subsequent introduction of a zero TAC in 1998, targeting shifted to black teatfish, and what was thought to be surf redfish but is now understood to be primarily deepwater redfish and blackfish species (Skewes et al. 2010).

ABARES received substantial updates to catch data for the TSBDMF in 2017 as a result of a concerted effort by the Australian Fisheries Management Authority (AFMA) in early 2017 to follow up on unreported catch records. This process has resulted in substantially higher catch totals for some sea cucumber species in some years.

Total catch for the TSBDMF in 2015 was previously reported as approximately 31 t (Patterson et al. 2016). This figure is now understood to be closer to 73 t, bolstered by relatively large increases in the reported catch of prickly redfish and white teatfish (Table 19.2). Total reported catch dropped to just under 15 t in 2016, with prickly redfish making up more than 70 per cent of this catch (Table 19.2).

TABLE 19.2 Main features and statistics for the TSBDMF and the TSTF
Fishery statistics a 201520152015201620162016
Stock TAC
(t)
Catch
(t)
Real value (2014–15)
TAC
(t)
Catch
(t) b
Real value
(2015–16)
Black teatfish1523.3 bna000
Prickly redfish2028.1na2011.2na
Sandfish01 cna00.5 cna
White teatfish154.2na151na
Other sea cucumber species (18 species)8016.4na802.2na
Total fishery (TSBDMF) 130 73 na 115 14.9 na
Trochus1500015000
Total fishery (TSTF) 150 0 0 150 0 0

Fishery-level statistics 20152016
Effort (no. of sellers)Bêche-de-mer: 81
Trochus: 0
Bêche-de-mer: 24
Trochus: 0
Fishing permits (as at 30 June)Bêche-de-mer: 95
Trochus: 77
Bêche-de-mer: 124
Trochus: 71
Active vesselsnana
Observer coverage00
Fishing methodsHand collection—free-dive or reef walkingHand collection—free-dive or reef walking
Primary landing portsIsland processors and mobile product buyersIsland processors and mobile product buyers
Management methods
Bêche-de-mer
Trochus
Input controls: limited entry, gear restrictions, vessel length restrictions
Output controls: TACs, size limits

Input controls: limited entry, gear restrictions, vessel length restrictions
Output controls: TACs, size limits
Input controls: limited entry, gear restrictions, vessel length restrictions
Output controls: TACs, size limits

Input controls: limited entry, gear restrictions, vessel length restrictions
Output controls: TACs, size limits
Primary markets
Bêche-de-mer
Trochus
Domestic: minimal
International: Asia—predominantly Hong Kong, Singapore and China

Domestic: minimal
International: historically, markets have included China, France, Germany, Italy, Japan, the Philippines, Spain, Thailand, the United Kingdom and the United States
Domestic: minimal
International: Asia—predominantly Hong Kong, Singapore and China

Domestic: minimal
International: historically, markets have included China, France, Germany, Italy, Japan, the Philippines, Spain, Thailand, the United Kingdom and the United States
Management planNo formal management plansNo formal management plans

a Fishery statistics are provided by fishing season, unless otherwise indicated. Fishing season is 1 January to 31 December. Real-value statistics are by financial year. Reported catch is understood to be gutted wet weight. b Catch taken during trial; the black teatfish fishery remains closed. c Illegal, unreported and unregulated catch from foreign vessels.
Notes: na Not available. TAC Total allowable catch.

19.2 Biological status

Black teatfish (Holothuria whitmaei)

Black teatfish 

Line drawing: FAO

Stock structure

Black teatfish in Torres Strait is assumed to represent a single biological stock (T Skewes, CSIRO, 2013, pers. comm.).

Stock assessment

The Torres Strait black teatfish stock was last surveyed in 2009 (Skewes et al. 2010). This survey showed increases in the mean density (from fewer than 1 individual per hectare to just over 10 individuals per hectare), mean length (an increase of almost 6 per cent) and mean weight (an increase of more than 11 per cent) of black teatfish compared with the 2005 survey. However, there is considerable uncertainty around these estimates. Because of the increased densities and animal size, Skewes et al. (2010) recommended reopening the fishery for black teatfish with a TAC of 25 t, which would be an extraction rate of about 4 per cent of the lower 90th percentile of the standing stock estimate (estimated at 625 t). A separate study of black teatfish on the Great Barrier Reef had estimated that harvest rates of less than 5 per cent of the virgin biomass were likely to be sustainable (Uthicke et al. 2003).

In November 2011, the Hand Collectables Working Group, informed by the outcomes of Skewes et al. (2010), considered options for increasing the zero TAC. It noted that increasing the TAC would result in increased targeting of this species, which would likely stimulate interest in the fishery. It also acknowledged that a level of precaution is required in developing the fishery to minimise the risks of exceeding the TAC, localised depletion and unsustainable harvest of other species. As a result, the PZJA endorsed a one-month trial of fishing for black teatfish in 2014 and 2015, operating under a 15 t TAC. Some overcatch was recorded in both years (see Table 19.2). A zero TAC was set for 2016.

Stock status determination

There was no reported catch in 2016. On this basis, the stock is classified as not subject to overfishing. Given the indications of recovery from the most recent survey, black teatfish is classified as not overfished.

Prickly redfish (Thelenota ananas)

Prickley redfish 

Line drawing: FAO

Stock structure

Prickly redfish in Torres Strait is assumed to represent a single biological stock (T Skewes, CSIRO, 2013, pers. comm.).

Stock assessment

The Torres Strait prickly redfish stock was last surveyed in 2009 (Skewes et al. 2010). This survey indicated that densities had remained relatively stable across surveys in 1995, 2002, 2005 and 2009, ranging from 1.42 to 2.15 prickly redfish per hectare. Between 2005 and 2009, the density increased from 1.44 to 1.99 prickly redfish per hectare. The mean size of prickly redfish increased from 2,147 to 2,812 g between 2005 and 2009. Well-established and consistent methodologies were used in the surveys, but considerable uncertainty remains around these estimates.

The current TAC for prickly redfish (20 t) is based on an estimate of maximum sustainable yield (MSY), using a biomass estimate from the 2002 survey (Skewes et al. 2004). MSY was estimated using a simplified surplus production model that relies on estimates of biomass and natural mortality (M). The surplus production model assumed an MSY of 0.2MB0 and used the lower bound of the 90 per cent confidence interval of the 2002 estimate of standing stock (approximately 343 t) as B0. Following the 2002 survey of eastern Torres Strait, Skewes et al. (2004) classified prickly redfish as ‘exploited' where the population was currently being fished, or had previously been fished, but showed no evidence of severe depletion. The application of meta-rules for calculating the TAC, based on the level of exploitation, led to the MSY estimate being halved, generating a TAC of 20 t. The combination of using the lower bound of the 90 per cent confidence interval for biomass, using a 0.2 scaling factor for natural mortality (instead of the more typical 0.5) and halving the final MSY estimate (to account for previous exploitation) resulted in a TAC that is considered to be conservative.

Stock status determination

Since calculation of the TAC in 2004, catches of prickly redfish have been sporadic, but increasing. Reported catch1 has been below the 20 t TAC in every year except 2015, when it exceeded 28 t. While the data that support the current TAC are close to 15 years old, the average catch for the period since the TAC was calculated (2004) has been substantially below the 20 t TAC (around 6 t per year). On this basis, the stock is classified as not subject to overfishing. Densities, lengths and weights of prickly redfish remained relatively stable between 1995 and 2009, and there are no more recent data to indicate that this situation has changed. As a result, the stock is classified as not overfished.

Sandfish (Holothuria scabra)

Sandfish 

Line drawing: FAO

Stock structure

Sandfish in Torres Strait is assumed to represent a single biological stock (T Skewes, CSIRO, 2013, pers. comm.).

Stock assessment

The Torres Strait sandfish stock was last surveyed in 2010 (Murphy et al. 2011). At that time, survey densities were around 80 per cent lower than in 1995, when the stock was already considered to be depleted. Results from the survey indicated a mean density of 94 ± 50 sandfish per hectare (± standard error [SE]), which was similar to that in 2004 (94 ± 25 sandfish per hectare), suggesting that there had been no recovery up to the time of the 2010 survey. The reason for the lack of observable recovery of sandfish between 1998 and 2010 is not clear, given that the fishery has been closed since 1998. Murphy et al. (2011) suggested several possible causes, including illegal fishing and poor recruitment.

With respect to recruitment, Murphy et al. (2011) hypothesised that the relatively low density of sandfish remaining on Warrior Reef may have reduced fertilisation success, because remaining sandfish are widely dispersed. Murphy et al. (2011) also noted that sandfish can burrow into the sand, making them difficult for survey observers to see. However, Murphy et al. (2011) considered it unlikely that the proportion of buried sandfish would have differed from one survey to the next. This is because, all surveys sampled the same sites during the same season, lunar phase, tide and time of day, providing confidence in comparability of density estimates between years. Low density estimates in recent surveys are therefore likely to indicate actual low density, rather than underestimates resulting from increased proportions of buried sandfish.

In 2012, CSIRO and AFMA conducted a small-scale experimental fishing trial of the Warrior Reef sandfish stock (Murphy et al. 2012). Methodology differed significantly from that used in previous surveys. Differences included sampling at different ‘locations'2 from the previous surveys (only three previous ‘sites' were included), walking random search tracks rather than straight-line transects and choosing fishing areas of known high density (see Murphy et al. 2012). Previous survey reports emphasised the importance of sampling at the same sites (at the same lunar phase, tide and time of day) for each survey, to allow repeated measures for statistical analysis of data (for example, Murphy et al. 2010). Given the methodological differences, caution should be used when comparing the 2012 work with previous surveys. Although the findings of the 2012 study indicate that the density, biomass and size frequency of the stock had improved, it is unclear whether these data reflect real improvements in the stock or are artefacts of the different experimental design. The stock status determination provided here therefore continues to rely on the findings of the most recent full-scale sandfish survey (Murphy et al. 2010).

ABARES has received information confirming the illegal catch of sea cucumbers on Warrior Reef by PNG nationals in recent years (AFMA, 2017, pers. comm.). Approximately 0.4 t of catch was found on apprehended vessels in 2016, and approximately 1 t of catch in 2015. These catches are understood to be made up primarily of sandfish.

Stock status determination

Sandfish has been subject to a zero TAC since 1998. Illegal catch taken by PNG nationals has been reported in recent years. However, it is not clear whether the level of illegal catch found on apprehended vessels would impair recovery of the stock. It is also unclear whether the level of catch found on apprehended vessels represents the full extent of IUU catch. On this basis, fishing mortality status is uncertain. Since no recovery in overall density was observed between the full-scale surveys in 2004 and 2010, and there is no other robust information to inform stock status, the stock remains classified as overfished.

White teatfish (Holothuria fuscogilva)

White teatfish 

Line drawing: FAO

Stock structure

White teatfish in Torres Strait is assumed to represent a single biological stock (T Skewes, CSIRO, 2013, pers. comm.).

Stock assessment

The Torres Strait white teatfish stock was last surveyed in 2009 (Skewes et al. 2010). The results of this survey indicated that white teatfish density was relatively stable (or possibly increased) between surveys in 1995, 2002 and 2005. Mean density (±SE) increased from 0.47 (±0.20) to 0.85 (±0.43) per hectare between 2005 and 2009 (Skewes et al. 2010). Differences in the density estimates among years were not statistically significant. Between 2005 and 2009, mean weight increased from 2,341 to 2,736 g, and mean length increased from 276 to 296 mm.

The 2009 survey estimated the biomass of white teatfish to be 110 t. The resulting TAC for white teatfish (using the same methods described for prickly redfish) was 15 t. However, it is likely that this survey underestimated the biomass, as a result of the 20 m safety limit imposed on diving depth for survey operations. White teatfish can occur at depths of more than 40 m, and previous research indicates that the majority inhabit waters deeper than 20 m (SPC 1994). Furthermore, the northern Don Cay region (Figure 19.1) was not included in the survey, potentially contributing to an underestimate of stock size. Past surveys may also have underestimated abundance and biomass for similar reasons. Given the historical restrictions on the use of breathing apparatus in this fishery, the depth preference of white teatfish is also likely to have protected the species from some level of fishing effort.

Stock status determination

Recent catches of white teatfish have been sporadic, with all but two years (2013 and 2014) being below the TAC. Although the data that support the current TAC are close to 15 years old, the average catch for the period since the TAC was calculated (2004) has been substantially below the 15 t TAC (around 5.5 t per year).

The reported catch in 2016 was around 1 t, substantially less than the 15 t TAC. This stock is therefore classified as not subject to overfishing. The relatively stable densities, mean weights and lengths from surveys up to 2009 indicate that the portion of stock available to the fishery has remained relatively stable. Because there are no more recent data to indicate that this situation has changed, this stock is classified as not overfished.

Other sea cucumbers (18 species)

Surf redfish 

Line drawing: FAO

Stock structure

The ‘other sea cucumber' stock is a basket stock made up of up to 18 species of sea cucumber. Together, these species are considered to constitute a single stock for management purposes.

Stock assessment

Many of the individual species within this multispecies stock have been included in previous surveys (1995, 2002, 2005 and 2009) of sea cucumbers in Torres Strait. The results of the 2002 survey were used to estimate MSY, and subsequently TACs, for 15 of the species (see section on prickly redfish for methodology for MSY and TAC calculation). For species considered to be ‘unexploited' (that is, little or no fishing currently or in the recent past), the recommended TAC was equal to the estimate of MSY; for species currently or previously fished, but showing no evidence of severe depletion, the recommended TAC was half of MSY; and for species considered ‘overexploited' (where the population is severely depleted and densities are several times lower than unfished biomass levels) or with MSY estimates less than 10 t, the recommended TAC was zero. Because of the multispecies nature of this stock, the PZJA has established an 80 t TAC for all species combined. This TAC is not biologically meaningful at the individual species level. The reported catch for this multispecies stock in 2015 was around 2 t.

Stock status determination

Catch of this stock in 2016 comprised a number of species, none of which are considered to have been depleted to low levels. As such, the stock is considered to be not subject to overfishing.

At the time of the last full-scale survey, some species that make up this multispecies stock were considered to have been reduced to low levels by historical fishing. Further, it has been a number of years since the last survey was undertaken. As a result, the biomass status of some species, and therefore the stock as a whole, remains uncertain.

Trochus (Trochus niloticus)

Trochus (Trochus niloticus) 

Line drawing: FAO

Stock structure

Trochus in Torres Strait is assumed to represent a single biological stock (T Skewes, CSIRO, 2013, pers. comm.).

Stock assessment

Trochus was surveyed in Torres Strait in 1995, 2002, 2005 and 2009, mostly in combination with surveys of sea cucumbers and other reef-dwelling marine resources. The 2009 survey sampled 113 sites (11 specifically for trochus) over 10 days, during which 73 specimens were found at 12 sites. The survey transects sampled to a depth of 20 m, but trochus was not found deeper than 3 m. Murphy et al. (2010) suggested that the low numbers, and often complete absence, of trochus may be because trochus has quite different habitat requirements from those of bêche-de-mer. When suitable trochus habitat was identified and specifically targeted, animals were commonly found. In the 2009 survey, the average density of trochus was estimated at 25 individuals per hectare (lower 90th percentile: 5 individuals per hectare), with a standing stock estimate of 634 t (lower 90th percentile: 138 t). The density of trochus in 2009 was similar to that observed in 1995, and the authors suggested that it was comparable to that of unfished stocks in other South Pacific locations.

Despite the well-established and repeated methodology used in the surveys, the reliability of the estimates of density and standing stock is uncertain because of the small number of sites at which trochus was found (only 12 of 113 sites), the low total number of trochus observed (73) and the resulting high variability around mean estimates of density. Murphy et al. (2010) concluded that the density estimates had very low precision and that the probability of detecting even large changes in trochus density was low.

Murphy et al. (2010) recommended setting a trigger catch level of 75 t (live shell weight), based on historical information, anecdotal harvest patterns and a 20 per cent exploitation rate of the estimated standing stock. It was recommended that the TAC should be reassessed and a stock assessment undertaken if catch exceeded this level. The current TAC for trochus in Torres Strait is 150 t, but there is no robust assessment or survey basis for that level of catch (Murphy et al. 2010).

Stock status determination

There was no reported catch of trochus in 2016. As a result, the stock is classified as not subject to overfishing. Given the long history of fishing for trochus in Torres Strait (pre-European settlement; DPIE 1994), the unfished biomass is unknown. Furthermore, although the results of the 2009 survey suggested that trochus densities were similar to unfished stocks in other South Pacific locations, the very low precision of the results means that the biomass status of trochus remains uncertain.

19.3 Economic status

Key economic trends

Estimates of net economic returns (NER) are not available for the TSBDMF or the TSTF. Estimates of the gross value of production are also not available for either fishery.

Because it is relatively easy to collect sea cucumbers, and the value of, and demand (mostly from Asia) for, sea cucumber are increasing, the stock needs to be closely monitored to avoid overfishing. Most of Australia's export of sea cucumber is to China, Hong Kong and Singapore. The level of participation in the TSTF is relatively low because of a decline in overseas market demand for shells.

Management arrangements

Both fisheries are managed under TACs and a range of input controls. For the TSBDMF, only a trial TAC for black teatfish was caught in 2015. With the increased TAC for black teatfish, the catch of other species, such as prickly redfish, increased significantly during the trial. For the TSTF, no catch has been recorded since 2010, suggesting that it is not profitable.

The trial TAC of black teatfish in the TSBDMF contributed to increased catches in the 2014 and 2015 fishing seasons, which likely increased NER during this period. The trial TAC ended in 2016, resulting in lower activity in the fishery and therefore lower catches—mostly of prickly redfish and black teatfish—suggesting a decline in NER.

Performance against economic objective

The HSP is not prescribed for Torres Strait fisheries, and there are no explicit economic targets for the TSBDMF or the TSTF.

For the TSBDMF, the PZJA aims to provide for the sustainable use of the resource, develop stocks for the benefit of Australian Traditional Inhabitants and develop a long-term strategy for sandfish (PZJA 2014a). The trial of black teatfish catch in 2014 and 2015, and hookah gear trials in 2011–12 appear to have generated increased activity in the TSBDMF. Rebuilding the sandfish stock should increase the potential benefits to local communities from the fishery.

For the TSTF, the PZJA aims to make best use of the resource, maximise opportunities for Traditional Inhabitants and encourage participation in the fishery (PZJA 2014b). Expectations of low economic returns are likely to have contributed to low participation in the fishery.

19.4 Environmental status

Both the bêche-de-mer and trochus fisheries are included in the List of Exempt Native Specimens under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). The TSBDMF is exempt from export controls until 27 October 2017, and the TSTF is exempt until 22 December 2017.

No ecological risk assessments have been conducted for the bêche-de-mer fishery or the trochus fishery. The most recent EPBC Act assessments of the fisheries (Department of the Environment 2014) assume that impacts on the ecosystem of each fishery would be restricted to exploitation of target species; translocation of species through anchor and hull fouling; and impacts on reef ecosystems related to anchoring, mooring and other anthropogenic activities, such as reef-top walking.

AFMA publishes quarterly reports of logbook interactions with protected species on its website. No interactions with species protected under the EPBC Act were reported in either fishery in 2016.

19.5 References

AFMA 2011, Annual status report, Torres Strait Trochus Fishery strategic and export accreditation, Australian Fisheries Management Authority, Canberra.

—— 2013, Annual report, Torres Strait Bêche-de-mer Fishery 2013, AFMA, Canberra.

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

Department of the Environment 2014, Assessment of the Torres Strait Bêche-de-mer Fishery, Australian Government Department of the Environment, Canberra.

DPIE 1994, Fisheries and marine research in Torres Strait, Bureau of Resource Sciences, Australian Government Department of Primary Industries and Energy, Canberra.

Murphy, NE, McLeod, I, Skewes, TD, Dovers, E, Burridge, C & Rochester, W 2010, Torres Strait hand collectables, 2009 survey: trochus, CSIRO Marine and Atmospheric Research, Cleveland, Queensland.

——, Skewes, T, Filewood, F, David, C, Seden, P & Jones, A 2011, The recovery of the Holothuria scabra (sandfish) population on Warrior Reef, Torres Strait, final report to AFMA, CSIRO Marine and Atmospheric Research, Cleveland, Queensland.

——, Skewes, TD, Dovers, E & Leatherbarrow, A 2012, Assessing stock recovery using experimental fishing for sandfish on Warrior Reef, Torres Strait, final report, CSIRO, Dutton Park, Queensland.

Patterson, H, Noriega, R, Georgeson, L, Stobutzki, I & Curtotti, R 2016, Fishery status reports 2016, ABARES, Canberra.

PZJA 2014a, ‘Torres Strait Bêche-de-mer Fishery', Torres Strait Protected Zone Joint Authority, http://pzja.gov.au/the-fisheries/torres-strait-beche-de-mer-fishery.

—— 2014b, ‘Torres Strait Trochus Fishery', PZJA, http://pzja.gov.au/the-fisheries/torres-strait-trochus-fishery.

Skewes, T, Dennis, DM, Koutsoukos, A, Haywood, M, Wassenberg, T & Austin, M 2004, Stock survey and sustainable harvest strategies for Torres Strait bêche-de-mer, AFMA project R01/1345, CSIRO Marine and Atmospheric Research, Cleveland, Queensland.

—— , Murphy, NE, McLeod, I, Dovers, E, Burridge, C & Rochester, W 2010, Torres Strait hand collectables, 2009 survey: sea cucumber, CSIRO Marine and Atmospheric Research, Cleveland, Queensland.

SPC 1994, Sea cucumbers and bêche-de-mer of the tropical Pacific: a handbook for fishers, handbook 18, Secretariat of the Pacific Community, Noumea.

Uthicke, S, Welch, D & Benzie, JAH 2003, ‘Slow growth and lack of recovery in overfished holothurians on the Great Barrier Reef: evidence from DNA fingerprints and repeated large-scale surveys', Conservation Biology, vol. 18, pp. 1395–404.

Footnotes

7Reported catches of sea cucumbers are understood to be gutted wet weight.

8The term ‘location' was used in the 2012 experimental fishing trial rather than ‘site'. These locations were data logger tracks that indicated where experimental fishing occurred. They were labelled locations rather than sites because they were not generally separated by 500 m, a characteristic of the sites used in previous full-scale stock surveys. Locations were chosen by individual fishers rather than being specified by experimental design. Of the 37 locations fished, 14 were next to three sites surveyed for sandfish in previous years (N Murphy, CSIRO, 2013, pers. comm.).

White teatfish
Tim Skewes, CSIRO
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Last reviewed:
09 Feb 2018