Chapter 16: Torres Strait Finfish Fishery
N Marton, A Williams and K Mazur
TABLE 16.1 Status of the Torres Strait Finfish Fishery
| Fishing mortality|| Biomass||Fishing mortality||Biomass|| |
|Not subject to overfishing||Not overfished|| Not subject to overfishing|| Not overfished||Management 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.|
|Not subject to overfishing||Not overfished|| Not subject to overfishing|| Not overfished||Current fishing mortality rate is below that required to produce MSY. Most recent estimates of biomass are above B20. |
Economic status||Estimates of net economic returns are not available. Economic performance in 2016–17 remains uncertain because of varied levels of fishing by different operations, seasonal prices for key species and fishing costs.|
Notes: B0 Unfished biomass. B220 20% of unfished biomass. MSY Maximum sustainable yield.
16.1 Description of the fishery
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 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 larger primary vessel or operating independently. Byproduct is a relatively minor component of catch. 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., Variola spp.), with smaller catches of other groupers/cods (Serranidae), mackerels (Scombridae), snappers (Lutjanidae), emperors (Lethrinidae) and trevally (Carangidae). The most recent data indicate that coral trout make up more than 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 represents 2 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).
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 annual licence (called a ‘sunset licence’). These operators lease quota for Spanish mackerel, coral trout and other finfish 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.
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 in the TIB and TVH sectors has followed the trends in effort, discussed above.
TABLE 16.2 Main features and statistics for the TSFF
a||2015–16 fishing season||2016–17 fishing season|
|Total fishery||129.1||$1.2 million||121.1||$1.2 million|
c —412 operation-days, 764 tender-days
Sunset permits—344 (coral trout operation- and tender-days), 344 (all TSFRLF species operation- and tender-days)
Sunset permits—396 operation-days, 849 tender-days
Sunset permits—205 coral trout operation-days, 205 tender-days (same for all TSFRLF species)
|Fishing permits||TIB: 143 mackerel endorsements, 123 line endorsements
Sunset permits: 7 mackerel and/or line licences
|TIB: 266 mackerel endorsements, 248 line endorsements
Sunset permits: 7 mackerel and/or line licences
|Observer coverage||0 days||0 days|
|Fishing methods||Coral trout and mixed reef species: handline, rod and line
Spanish mackerel: trolled baits, lures and handlines
|Primary landing ports||Cairns (Queensland); Torres Strait Island fish receivers on Erub (Darnley), Masig (Yorke) and Mer (Murray) islands|
|Management methods||Input controls: limited entry, vessel restrictions, prohibited species
Output controls: size limits, amount of leased quota
|Primary markets||Domestic: frozen
|Management plan||Torres Strait Finfish Fishery Management Plan 2013|
a Fishery statistics are provided by fishing season, unless otherwise indicated. Fishing season is 1 July – 30 June. Real-value statistics are provided
by financial year and are in 2016–17 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.
cAll 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.
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.)
Line drawing: FAO
Coral trout in Torres Strait comprise four species: common coral trout (Plectropomus leopardus), barcheek coral trout (P. maculatus), passionfruit coral trout (P. areolatus) and bluespot coral trout (P. laevis). Each of these species is likely to be a single genetic stock in Torres Strait (Evans et al. 2010). The species are usually not distinguished in fishery logbooks. Therefore, the status is reported for the Torres Strait fishery rather than for individual species or stocks.
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.
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; Williams, Little & Begg 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 2016–17 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. 2007; Williams, Little & Begg 2011). Reported 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; Williams, Little & Begg 2011).
Catch from the TIB Sector is likely to have been under-reported in the past because it was not mandatory for this sector to report catch-and-effort data. Reporting for the TIB Sector only became mandatory on 1 December 2017 (through the fish receiver system; see Chapter 15), and then only for catch that is sold commercially; reporting is still not required for subsistence fishing. Furthermore, representatives of the TIB Sector have advised that catches in the sector have increased in recent years (AFMA 2017). The unknown catch from the TIB Sector, together with the age of the MSE, give some cause for caution. However, effort for the TIB Sector has historically been around four to five times lower than that for the TVH Sector, with the difference in catch volumes even larger (Williams et al. 2008). As such, while the likely under-reporting and increased TIB catches are of interest, and should be monitored closely through the new fish receiver system, the likely magnitude of total catches is unlikely to have reached the 80 t level simulated in the MSE in any year since 2004. As a result, the stock is classified as not overfished and not subject to overfishing.
Spanish mackerel (Scomberomorus commerson)
Line drawing: FAO
Spanish mackerel in Torres Strait comprise a separate biological stock from Spanish mackerel on the Queensland east coast and further west across northern Australia (Begg et al. 2006; Buckworth et al. 2007).
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 80–100 t since (Figure 16.3).
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 (2010–2014) 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 2016–17, the catch of coral trout declined but unit prices increased (Figure 16.4). The increase in catch of Spanish mackerel and decline in catch of coral trout resulted in little change in the gross value of production, which remained at $1.2 million in 2016–17.
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 $188,000 in 2015–16 (TSRA 2015).
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 and $1.5 million at the end of 2016–17 financial year (TSRA 2016, 2017). 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 18 December 2020.
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 by 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.
The Australian Fisheries Management Authority 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 2017.
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