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Silver Trevally

Pseudocaranx georgianus, Pseudocaranx sp. "dentex" & Pseudocaranx wrighti

  • Rowan Chick (Department of Primary Industries, New South Wales)
  • Anthony Roelofs (Department of Agriculture and Fisheries, Queensland)
  • Corey Green (Department of Economic Development, Jobs, Transport and Resources, Victoria)
  • David Fairclough (Department of Fisheries, Western Australia)
  • John Stewart (Department of Primary Industries, New South Wales)
  • Lee Georgeson (Australian Bureau of Agricultural and Resource Economics and Sciences)
  • Timothy Emery (Institute for Marine and Antarctic Studies, University of Tasmania)

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Stock Status Overview

Stock status determination
Jurisdiction Stock Fisheries Stock status Indicators
Commonwealth Commonwealth SESSF (CTS) Sustainable Catch, CPUE
SESSF (CTS)
Southern and Eastern Scalefish and Shark Fishery (Commonwealth Trawl Sector) (CTH)
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Stock Structure

Silver Trevally contains a complex of species that inhabits estuarine and coastal waters (depths of 10–230 m), throughout southern temperate Australia, from southern Queensland, south through New South Wales, Tasmania, South Australia and southern and central Western Australia1.

The biological stock structure of Silver Trevally is uncertain. Defining stock structure is complicated by the fact that stock assessments of Silver Trevally apply to a species complex in the Commonwealth, Western Australia, Queensland, New South Wales, Victoria and Tasmania jurisdictions. This complex comprises Pseudocaranx georgianus (in all jurisdictions, excluding Queensland), P. dinjerra (Western Australia), P. wrighti (Western Australia) and P. sp. ‘dentex’ (Queensland)1.

Here, assessment of stock status is presented at the jurisdictional level—Commonwealth, Western Australia, Queensland, New South Wales, Victoria and Tasmania.

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Stock Status

Commonwealth

A peak catch in 1990 of 1588 tonnes (t), and high catch rates between 1989 and 1991 resulted from highly efficient vessels using trawl gear entering the Commonwealth fishery in 1989. The Commonwealth fishery extends beyond state jurisdictional waters. These initial catch rates were apparently not sustainable2 and catch has since declined.

Before 2010, most of the Silver Trevally catch was taken in state waters outside the Southern and Eastern Scalefish and Shark Fishery3. The closure of Silver Trevally trawling grounds within the Batemans Marine Park in 2007, and the buy-out of New South Wales fishing businesses before 2007, have reduced overall fishing effort, contributing to a reduction in recent catches3. Catch in the Commonwealth Trawl and Scalefish Hook sectors decreased from 93 t in 2014–15 to 72 t in 2015–16. All of the catch in 2015–16 was taken in the trawl sector.

The 2013 tier 4 (catch per unit effort [CPUE]) assessment4 used the reference period 1992–2001. CPUE declined rapidly from 1993, to be near the limit reference point of 20 per cent of unfished biomass by 2002. CPUE then increased to 2010, when it was above the target, but has since declined4. The 2013 tier 4 assessment4 showed 4-year average CPUE to be near the target level. The above evidence indicates that the stock is unlikely to be recruitment overfished.

The 2013 assessment produced a 1-year recommended biological catch (RBC) of 858 t and a 3-year RBC of 791 t, which was endorsed by the Shelf Resource Assessment Group5. The Australian Fisheries Management Authority subsequently set a 3-year Commonwealth annual total allowable catch (TAC) of 615 t for the 2013–14 to 2015–16 fishing seasons. Considering estimated state catches and discards, the 2015–16 TAC for the Commonwealth sector was set at 602 t. Catches in the past seven fishing seasons have been well below the RBC.

The above evidence indicates that the current level of fishing pressure is unlikely to cause the stock to become recruitment overfished.

On the basis of the evidence provided above, Silver Trevally in the Commonwealth is classified as a sustainable stock.

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Biology

Silver Trevally biology11,16,17

Biology
Species Longevity / Maximum Size Maturity (50 per cent)
Silver Trevally 13-18 years; 690-938 mm TL 190-200 mm TL
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Distributions

Distribution of reported commercial catch of Silver Trevally

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Tables

Fishing methods
Commonwealth
Commercial
Danish Seine
Otter Trawl
Management methods
Method Commonwealth
Commercial
Fishing gear and method restrictions
Limited entry
Spatial closures
Total allowable catch
Active vessels
Commonwealth
31 in SESSF (CTS)
SESSF (CTS)
Southern and Eastern Scalefish and Shark Fishery (Commonwealth Trawl Sector) (CTH)
Catch
Commonwealth
Commercial 80.20t in SESSF (CTS)
SESSF (CTS)
Southern and Eastern Scalefish and Shark Fishery (Commonwealth Trawl Sector) (CTH)

a Commonwealth – Recreational The Australian Government does not manage recreational fishing in Commonwealth waters. Recreational fishing in Commonwealth waters is managed by the state or territory immediately adjacent to those waters, under its management regulations.
b Commonwealth – Indigenous The Australian Government does not manage non-commercial Indigenous fishing in Commonwealth waters, with the exception of the Torres Strait. In general, non-commercial Indigenous fishing in Commonwealth waters is managed by the state or territory immediately adjacent to those waters.
c Tasmania – Recreational (management methods) In Tasmania, a recreational licence is required for fishers using dropline or longline gear, along with nets, such as gillnet or beach seine.
d Western Australia – Recreational (management methods) In Western Australia, a licence is required to recreationally fish from a powered vessel.
e New South Wales – Recreational (management methods) In New South Wales there are four charter boat endorsement categories (Estuarine Fishing, Nearshore Bottom Fishing and Sportfishing, Gamefishing and Deep Sea Bottom Fishing). The different categories have limitations on the species of fish they can access.
f New South Wales – Indigenous (management methods) Aboriginal Cultural Fishing Interim Access Arrangement - allows an Indigenous fisher in New South Wales to take in excess of a recreational bag limit in certain circumstances, for example, if they are doing so to provide fish to other community members who cannot harvest themselves.
g New South Wales – Indigenous (management methods) Aboriginal cultural fishing authority - the authority that Indigenous persons can apply to take catches outside the recreational limits under the Fisheries Management Act 1994 (NSW), Section 37 (1)(c1), Aboriginal cultural fishing authority.
h Queensland – Indigenous (management methods) In Queensland, under the Fisheries Act 1994 (Qld), Indigenous fishers are able to use prescribed traditional and non-commercial fishing apparatus in waters open to fishing. Size and possession limits, and seasonal closures do not apply to Indigenous fishers. Further exemptions to fishery regulations may be applied for through permits.
i Victoria – Indigenous (management methods) In Victoria, regulations for managing recreational fishing are also applied to fishing activities by Indigenous people. Recognised Traditional Owners (groups that hold native title or have agreements under the Traditional Owner Settlement Act 2010 [Vic]) are exempt (subject to conditions) from the requirement to hold a recreational fishing licence, and can apply for permits under the Fisheries Act 1995 (Vic) that authorise customary fishing (for example, different catch and size limits or equipment). The Indigenous category in Table 3 refers to customary fishing undertaken by recognised Traditional Owners. In 2015, there were no applications for customary fishing permits to access Silver Trevally.
j Victoria – Indigenous (management methods) Subject to the defence that applies under Section 211 of the Native Title Act 1993 (Cth), and the exemption from a requirement to hold a Victorian recreational fishing licence, the non-commercial take by indigenous fishers is covered by the same arrangements as that for recreational fishing.
k Tasmania – Indigenous (management methods) In Tasmania, aborigines engaged in aboriginal fishing activities in marine waters are exempt from holding recreational fishing licences, but must comply with all other fisheries rules as if they were licensed. Additionally, recreational bag and possession limits also apply. If using pots, rings, set lines or gillnets, Aborigines must obtain a unique identifying code (UIC). The policy document Recognition of Aboriginal Fishing Activities for issuing a Unique Identifying Code (UIC) to a person for Aboriginal Fishing activity explains the steps to take in making an application for a UIC.

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Catch Chart

Commercial catch of Silver Trevally

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Effects of fishing on the marine environment

  • There is bycatch in the fish trawl sector. In 2006, mandatory requirements for otter trawls to use 90 mm square-mesh codend panels were introduced in an effort to reduce the bycatch of small species and juvenile fish19.
  • Interactions can occur with animals protected under the Environment Protection and Biodiversity Conservation Act 1999, including marine mammals (dolphins, seals and sea lions), seabirds, some shark species and seahorses and pipefish (syngnathids). These interactions are reported quarterly by the Australian Fisheries Management Authority (AFMA)20 and on-board observer programs are used to validate the reporting in commercial logbooks.
  • In 2007, the South East Trawl Fishing Industry Association released an industry code of practice that aims to minimise interactions with fur seals, as well as addressing the environmental impacts of the fishery more generally21. Operators have developed other mitigation protocols that have further reduced seal mortalities, including using breakaway ties that keep the net closed until it is below depths that seals regularly inhabit, adopting techniques to close the trawl opening during recovery to minimise opportunities for seals to enter the net, switching off gantry lights that are not required during night trawling to avoid attracting bait species and seals, and dumping offal only when the boat is not engaged in deploying or hauling gear21.
  • The AFMA mandated individual vessel seabird management plans22. The seabird action plans are used in the Southern and Eastern Scalefish and Shark Fishery (Commonwealth Trawl Sector) (SESSF [CTS]) to mitigate the impacts of trawling on seabirds. From 1 May 2017, all vessels in the SESSF (CTS) and Southern and Eastern Scalefish and Shark Fishery (Great Australian Bight Trawl Sector) (SESSF [GABTS]) fisheries must use one of the following mitigation devices: sprayers; bird bafflers; or pinkies with zero discharge of fish waste23.
  • The effects of trawl fishing on the marine environment are assessed through an environmental risk assessment and risk management framework and mitigated through spatial closures, and the implementation of bycatch and discard workplans24,25 in the SESSF (CTS) and SESSF (GABTS) fisheries.
  • Silver Trevally are targeted by commercial fisheries in New South Wales, using hauling and gillnetting, otter trawl and fish trap and handline gear. These gears also catch other species and undersize individuals and have implications for the marine environment2630.
  • Seabirds and other marine life often become entangled in discarded recreational fishing tackle31.
  • The Victorian Bays and Inlets commercial fishers have adopted responsible fishing practices32. It is likely that fishing activities have minimal impact on the environment.
  • Silver Trevally are targeted in Western Australia by commercial and recreational fisheries using mainly line fishing. This activity is considered to pose a low risk to the environment, such as the habitats6.
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Environmental effects on Silver Trevally

  • Silver Trevally is a schooling species inhabiting estuarine and near-shore ocean waters11, including structures on the continental shelf. Larger and older individuals more commonly caught in deeper waters (greater than 60 m) with juveniles more commonly inhabiting inshore waters (less than 20 m)16,17. Silver Trevally larvae have been found in greater numbers in deeper water (up to 100 m) in New South Wales waters33.
  • Changes in coastal currents and water temperatures associated with climate change have the potential to alter fish behaviours (for example, spawning activity and migration) and to affect the dispersal of eggs and larvae34, which may influence the subsequent recruitment and distribution of Silver Trevally.
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References

  1. 1 Smith-Vaniz WFand Jelks HL 2006, Australian trevallies of the genus Pseudocaranx (Teleostei: Carangidae), with description of a new species from Western Australia. Memoirs of Museum Victoria, 63: 97–106.
  2. 2 Haddon M 2013, Catch rate standardizations for selected species from the SESSF (data 1986–2012). CSIRO Marine and Atmospheric Research, Hobart.
  3. 3 Morison AK, Knuckey IA, Simpfendorfer CA and Buckworth RC 2013, South East Scalefish and Shark Fishery: draft 2012 stock assessment summaries for species assessed by GABRAG, ShelfRAG and Slope/DeepRAG. Report for AFMA, Canberra.
  4. 4 Haddon M 2013, Tier 4 analyses in the SESSF, including deep water species: data from 1986–2012. CSIRO Marine and Atmospheric Research, Hobart.
  5. 5 ShelfRAG 2013, Southern and Eastern Scalefish and Shark Fishery Shelf Resource Assessment Group (ShelfRAG), minutes, 25–27 September 2013, Tasmania. ShelfRAG, Australian Fisheries Management Authority, Canberra.
  6. 6 Fletcher WJ and Santoro K, (eds.) 2015, Status reports of the fisheries and aquatic resources of Western Australia 2014/15: The state of the fisheries, Department of Fisheries Western Australia, Perth.
  7. 7 Ryan KL, Hall NG, Lai EK, Smallwood CB and Taylor SM, Wise BS 2015, State-wide survey of boat-based recreational fishing in Western Australia 2013/14, Fisheries Research Report No. 268. Department of Fisheries, Western Australia, Perth.
  8. 8 Webley J, McInnes K, Teixeira D, Lawson A and Quinn R 2015, Statewide Recreational Fishing Survey 2013-14. Queensland Department of Agriculture and Fisheries, Brisbane.
  9. 9 Stewart J, Hegarty A, Young C, Fowler AM and Craig J 2015, Status of Fisheries Resources in NSW 2013-14. NSW Department of Primary Industries, Mosman.
  10. 10 West LD, Stark KE, Murphy JJ, Lyle JM and Ochwada-Doyle FA 2015, Survey of recreational fishing in New South Wales and the ACT, 2013/14, Fisheries Final Report Series. No. 149. NSW Department of Primary Industries.
  11. 11 Rowling KR and Raines LP 2000, Description of the biology and an assessment of the fishery for silver trevally Pseudocaranx dentex off New South Wales, Final Report to Fisheries Research and Development Corporation. Project 97/125. NSW Fisheries Final Report Series No. 24. NSW Fisheries, Cronulla.
  12. 12 Liggins GW 1996, The interaction between fish trawling (in NSW) and other commercial and recreational fisheries, Final Report to Fisheries Research and Development Corporation. FRDC Project No. 92/79. NSW Fisheries Research Institute, Cronulla.
  13. 13 Henry GW and Lyle JM 2003, The national recreational and Indigenous fishing survey. Fisheries Research and Development Corporation, Canberra.
  14. 14 Conron S, Giri K, Hamer P and Hall K 2016, Gippsland Lakes Fishery Assessment 2016, Fisheries Victoria Science Report Series No. 14. The Department of Economic Development, Jobs, Transport and Resources, Melbourne.
  15. 15 Conron S, Green C, Hamer P, Giri K and Hall K 2016, Corner Inlet- Nooramunga Fishery Assessment 2016, Fisheries Victoria Science Report Series No. 11. The Department of Economic Development, Jobs, Transport and Resources, Melbourne.
  16. 16 Farmer BM, French DJW, Potter IC, Hesp SA and Hall NG 2005, Determination of biological parameters for managing the fisheries for Mulloway and Silver Trevally in Western Australia, Fisheries Research and Development Corporation Report. FRDC Project 2002/004. Centre for Fish and Fisheries Research Murdoch University, Murdoch.
  17. 17 Smallwood CB, Hesp SA and Beckley LE 2013, Biology, stock status and management summaries for selected fish species in south-western Australia, Fisheries Research Report No. 242. Department of Fisheries, Western Australia.
  18. 18 Lyle JM, Stark KE and Tracey SR 2014, 2012–13 survey of recreational fishing in Tasmania. Institute for Marine and Antarctic Studies, University of Tasmania, Hobart.
  19. 19 Anon 2005, Australian Fisheries Management Authority 2005, SESSF Direction no. 05: gear requirements for the Commonwealth Trawl Sector. Australian Fisheries Management Authority, Canberra.
  20. 20 Australian Fisheries Management Authority, Protected species interaction reports, AFMA, Canberra.
  21. 21 SETFIA 2007, Industry Code of Practice to Minimise Interactions with Seals. South East Trawl Fishing Industry Association Ltd., Shearwater, Tasmania.
  22. 22 Australian Fisheries Management Authority, Seabirds, AFMA, Canberra.
  23. 23 AFMA 2016, AFMA moves to strengthen seabird safety. AFMA media release 15 July 2016 .
  24. 24 Australian Fisheries Management Authority 2014, Commonwealth Trawl Sector (Otter Board Trawl and Danish Seine) bycatch and discarding workplan 2014 - 2016, AFMA, Canberra.
  25. 25 Australian Fisheries Management Authority 2014, Great Australian Bight Trawl Sector bycatch and discarding workplan 2014 – 2016, AFMA, Canberra
  26. 26 New South Wales Department of Primary Industries 2001, Estuary General Fishery. Environmental Impact Statement. Public Consultation Document, Cronulla.
  27. 27 New South Wales Department of Primary Industries 2004, Ocean Trawl Fishery. Environmental Impact Statement. Public Consultation Document, Cronulla.
  28. 28 New South Wales Department of Primary Industries 2006, Ocean Trap and Line Fishery. Environmental Impact Statement. Public Consultation Document, Cronulla.
  29. 29 Gray CA, Broadhurst MK, Johnson DD and Young DJ 2002, Management implications of discarding in an estuarine multi-species gill net fishery. Fisheries Research, 56: 177–192.
  30. 30 Gray CA, Johnson DD, Broadhurst MK and Young DJ 2005, Seasonal, spatial and gear-related influences on relationships between retained and discarded catches in a multi-species gillnet fishery. Fisheries Research, 75: 56–72.
  31. 31 Campbell M 2013, Reducing the impact of discarded recreational fishing tackle on coastal seabirds, Fisheries Research and Development Corporation project 2011/057. Queensland Department of Agriculture Fisheries and Forestry, Brisbane.
  32. 32 VBlFA 2013, Environmental Management System. Victorian Bays and Inlets Fisheries Association, Victoria.
  33. 33 Gray CA 1993, Horizontal and vertical trends in the distribution of larval fishes in coastal waters off central New South Wales, Australia Marine Biology, 116: 649-666.
  34. 34 Hobday AJ, Poloczanska ES and Matear RJ, (eds.) 2008, Implications of climate change for Australian fisheries and aquaculture: a preliminary assessment, report to the Australian Government Department of Climate Change, Canberra.