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SILVER TREVALLIES (2018)

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

  • Ashley Fowler (Department of Primary Industries, New South Wales)
  • Rowan Chick (Department of Primary Industries, New South Wales)
  • Bradley Moore (Institute for Marine and Antarctic Studies, University of Tasmania)
  • David Fairclough (Department of Primary Industries and Regional Development, Western Australia)
  • Brent Womersley (Victorian Fisheries Authority)
  • Lee Georgeson (Australian Bureau of Agricultural and Resource Economics and Sciences)
  • Luke Albury (Department of Agriculture and Fisheries, Queensland)
  • Paul Rogers (South Australian Research and Development Institute)

You are currently viewing a report filtered by jurisdiction. View the full report.

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Summary

Silver Trevally inhabits estuarine and coastal waters throughout southern temperate Australia. Of the seven separate Australian stocks, five (in WA, SA, VIC, TAS and the Commonwealth) are sustainable. The NSW stock is depleting and the QLD stock is undefined.  

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Stock Status Overview

Stock status determination
Jurisdiction Stock Fisheries Stock status Indicators
New South Wales New South Wales EGF, OHF, OTF, OTLF Depleting Catch, CPUE, length and age structures
EGF
Estuary General Fishery (NSW)
OHF
Ocean Hauling Fishery (NSW)
OTF
Ocean Trawl Fishery (NSW)
OTLF
Ocean Trap and Line Fishery (NSW)
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Stock Structure

Silver Trevallies comprises 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, Victoria, South Australia and southern and central Western Australia [Smith-Vaniz and Jelks 2006].

The biological stock structure of Silver Trevallies is uncertain. Fisheries are based on a species complex that varies by region, with Pseudocaranx georgianus present in all jurisdictions except Queensland, P. wrighti present in all jurisdictions except Queensland and New South Wales, P. dinjerra only present in Western Australia, and P. sp. ‘dentex’ only present in Queensland [Smith-Vaniz and Jelks 2006, Gomon et al. 2008]. There have been no investigations of potential genetic structure within these species. Investigations of population connectivity and post-settlement movement are also limited. Despite fast swimming ability, tag-recapture studies in Western Australia, New South Wales and New Zealand indicate restricted post-settlement movement of P. georgianus, potentially leading to ecological stock structuring over moderate (hundreds of kilometres) spatial scales [James 1980, Fairclough et al. 2011, Fowler et al. 2018].

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

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Stock Status

New South Wales

Silver Trevallies (P. georgianus) stocks supported historical commercial catches in excess of 1 000 t per year in New South Wales during the 1980s, but the commercial catch has declined steadily since that time to 60 t in 2017; the lowest level in the history of the fishery. Interpreting this decline is complicated by changes in the historical reporting of catch between the state and Commonwealth jurisdictions, as well as management changes within New South Wales that have affected the spatial distribution of effort and fishery reporting through time. Within the state, reduction in the area available to commercial fisheries for Silver Trevallies, through the implementation of recreational fishing havens and marine parks (particularly the Batemans Marine Park), has likely reduced catch and potentially influenced catch rates, thereby creating difficulties in defining useful reference points to assess current stock status. A minimum legal length (MLL) of 300 mm TL was also introduced in late 2007, further impacting the quantity of landed catch and potentially confounding the interpretation of trends in fishery-dependent indicators through time.

Standardised catch rates (kg per day, hereafter ‘catch rates’) in New South Wales have either declined, or shown no clear trend, depending on the area and fishing method considered. The analysed period (1998–2017) is also characterised by declining effort across the state. Catch rates for fish trawling and fish trapping have declined since the late 1990s to early 2000s in the two ocean areas accounting for the greatest catch. Recent (2015–2017) catch rates for fish trapping in one of these areas have declined to 20 per cent of those achieved during 1998–2001. Declining catch rates for fish trawling in both areas during the most recent reporting year (2016–17) have brought catch rates to their lowest level since the introduction of the MLL in 2007. However, catch rates for fish trawling in other areas have shown no clear trend since the early 1990s, with annual estimates since 2009–10 surrounded by considerable uncertainty. The lack of a suitable reference period from which to evaluate changes in biomass (or a proxy) creates substantial uncertainty and will continue to hinder detection of biomass reductions to levels that might impair recruitment in New South Wales.

While acknowledging difficulties in interpreting the change, retained landings by resident recreational fishers in New South Wales have decreased substantially, with estimated landings declining from approximately 140 000 fish during 2000–01 to around 49 000 individuals during 2013–14 [West et al. 2015]. This corresponds to a decrease in retained catch weight from approximately 100 t during 2000–01 to around 27 t during 2013–14, based on average body weight. Mean catch rate (fish per day) of recreational fishers, not including charter boats, also declined from 0.05 to 0.03 between the two periods [West et al. 2015]. Due to the lack of certainty in defining the level of biomass depletion and despite substantial declines in commercial and recreational catch and CPUE since the late-1990s, the stock is not yet considered to be recruitment impaired, although caution must be applied to this outcome. This conclusion is also driven by a lack of certainty regarding stock boundaries, with some component of the stock likely shared with the neighbouring Commonwealth jurisdiction, which classified the resource as ‘sustainable’ given available evidence from that area.

Observer studies and monitoring of landed catches have shown that the length of Silver Trevallies captured by the OTF declined substantially between the periods 1987–90, 1993–95 and 1997–99 [Liggins 1996, Rowling and Raines 2000]. The proportion of larger-sized Silver Trevallies landed by New South Wales fisheries has continued to decline since 2007, when the MLL was introduced [Stewart et al. 2015].

As a result of declines in catch and proportion of larger fish, Silver Trevallies were last assessed as being growth overfished in New South Wales, with yield from the stock being limited by harvesting them at too small a length and at an excessive rate [Stewart et al. 2015]. The only age-based assessment of the Silver Trevallies stock indicated that total mortality increased substantially between 1987–90 and 1997–99 [Rowling and Raines 2000]. These analyses estimated that fishing mortality was greater than natural mortality by the 1997–99 period and that the fishery exhibited age class truncation. Given the ongoing length truncation observed in the fishery, it is likely that the total mortality rate and degree of age class truncation have persisted. Due to the MLL in New South Wales waters, discarding in the OTF is substantial and may exceed 50 per cent at times, based on number of individuals [NSW DPI, unpublished data]. Discard mortality of Silver Trevallies taken by trawling is likely to be substantial and possible mortality from discarding remains a concern to the status of the stock. Some protection to the Silver Trevallies stock is afforded by marine parks in eastern Australia, but total fishing mortality is still likely higher than natural mortality. The above evidence indicates that the current level of fishing mortality is likely to cause the stock to become recruitment impaired.

On the basis of the evidence provided above, Silver Trevallies in New South Wales is classified as a depleting stock.

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Biology

Silver Trevallies biology [Rowling and Raines 2000]

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 Trevallies

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Tables

Fishing methods
New South Wales
Commercial
Hook and Line
Mesh Net
Haul Seine
Otter Trawl
Unspecified
Fish Trap
Indigenous
Spearfishing
Hook and Line
Recreational
Spearfishing
Hook and Line
Charter
Hook and Line
Management methods
Method New South Wales
Charter
Passenger restrictions
Commercial
Fishing gear and method restrictions
Limited entry
Size limit
Spatial closures
Indigenous
Bag limits
Native Title
Section 37 (1d)(3)(9), Aboriginal cultural fishing authority
Recreational
Bag limits
Licence
Possession limit
Size limit
Spatial closures
Active vessels
New South Wales
106 in EGF, 15 in OHF, 24 in OTF, 108 in OTLF
EGF
Estuary General Fishery (NSW)
OHF
Ocean Hauling Fishery (NSW)
OTF
Ocean Trawl Fishery (NSW)
OTLF
Ocean Trap and Line Fishery (NSW)
Catch
New South Wales
Commercial 4.62t in EGF, 291.00kg in OHF, 34.99t in OTF, 12.32t in OTLF
Indigenous Unknown
Recreational 27 t (2013–14)
EGF
Estuary General Fishery (NSW)
OHF
Ocean Hauling Fishery (NSW)
OTF
Ocean Trawl Fishery (NSW)
OTLF
Ocean Trap and Line Fishery (NSW)

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. 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. Western Australia – Recreational (management methods) In Western Australia, a licence is required to recreationally fish from a powered vessel.

Western Australia – Recreational (Catch) Shore based catches are unknown, thus landings would be underestimated.

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.

New South Wales – Indigenous (a) The 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; (b) The Aboriginal cultural fishing authority is the authority that Indigenous persons can apply to take catches outside the recreational limits under the Fisheries Management Act 1994 (NSW), Section 37 (1d)(3)(9), Aboriginal cultural fishing authority; and (c) In cases where the Native Title Act 1993 (Cth) applies fishing activity can be undertaken by the person holding native title in line with S.211 of that Act, which provides for fishing activities for the purpose of satisfying their personal, domestic or non-commercial communal needs. In managing the resource where native title has been formally recognised, the native title holders are engaged with to ensure their native title rights are respected and inform management of the State's fisheries resources.

Victoria – Indigenous

In Victoria, regulations for managing recreational fishing may not apply to fishing activities by Indigenous people. Victorian traditional owners may have rights under the Commonwealth's Native Title Act 1993 to hunt, fish, gather and conduct other cultural activities for their personal, domestic or non-commercial communal needs without the need to obtain a licence. Traditional Owners that have agreements under the Traditional Owner Settlement Act 2010 (Vic) may also be authorised to fish without the requirement to hold a recreational fishing licence. Outside of these arrangements, Indigenous Victorians can apply for permits under the Fisheries Act 1995 (Vic) that authorise fishing for specific indigenous cultural ceremonies or events (for example, different catch and size limits or equipment). There were no Indigenous permits granted in 2017 and hence no Indigenous catch recorded.

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. The species is subject to a minimum size of 20 cm in Tasmanian waters. A bag limit of 10 individuals and a possession limit of 20 individuals is in place for recreational fishers.

Tasmania – Indigenous (management methods) In Tasmania, Indigenous persons 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, Indigenous fishers must obtain a unique identifying code (UIC). The policy document Recognition of Aboriginal Fishing Activities for issuing a 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 Trevallies - note confidential catch not shown

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References

  1. 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.
  2. 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.
  3. Fairclough, D, Walters, S, Holtz, M 2018, West Coast Demersal Scalefish Resource Status Report 2017. In Status reports of the fisheries and aquatic resources of Western Australia 2016/17: The state of the fisheries, eds DJ Gaughan and K Santoro. Department of Primary Industries and Regional Development, Western Australia, pp. 60–65.
  4. Fairclough, DV, Potter, IC, Lek, E, Bivoltsis, AK and Babcock, RC 2011, The fish communities and main fish populations of the Jurien Bay Marine Park, Centre for Fish and Fisheries Research, Murdoch University, Perth.
  5. Fowler, AM, Chick, RC, Stewart, J 2018, Patterns and drivers of movement for a coastal benthopelagic fish, Pseudocaranx georgianus, on Australia’s southeast coast. Scientific Reports, 8(1), 16738.
  6. Gaughan, DJ and Santoro, K (eds.) 2018, Status Reports of the Fisheries and Aquatic Resources of Western Australia 2016/17: The State of the Fisheries. Department of Primary Industries and Regional Development, Western Australia, Perth, Australia. 237p.
  7. Giri, K and Hall, K 2015, South Australian Recreational Fishing Survey. Fisheries Victoria Internal Report Series No. 62. 75 pp.
  8. Gomon, MF, Bray, DJ and Kuiter, RH (Eds.) 2008, Fishes of Australia's Southern Coast, Reed New Holland, Sydney.
  9. Haddon, M 2013, Tier 4 analyses in the SESSF, including deep water species: data from 1986–2012. CSIRO Marine and Atmospheric Research, Hobart.
  10. Haddon, M and Punt, A 2018, SimpleSA: A package containing functions to facilitate relatively simple stock assessments. R package version 0.1.10
  11. Haddon, M and Sporcic, M 2017, Tier 4 Assessments for selected SESSF Species (data to 2016). CSIRO Oceans and Atmosphere, Hobart. 52 p.)
  12. James, GD 1980, Tagging experiments on trawl-caught trevally, Caranx georgianus, off north-east New Zealand, 1973–79, New Zealand Journal of Marine and Freshwater Research, 14:249–254.
  13. 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.
  14. Lyle, JM, Stark, KE and Tracey, SR 2014, 2012–13 survey of recreational fishing in Tasmania. IMAS, Hobart.
  15. 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.
  16. Rogers, P.J, Tsolos, A, Boyle, M and Steer, M 2017, Data summary South Australian Charter Boat Fishery. Final Report to PIRSA Fisheries and Aquaculture. 25 pp.
  17. 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.
  18. Ryan, KL, Hall, NG, Lai, EK, Smallwood, CB, Taylor, SM and Wise, BS 2017, Statewide survey of boat-based recreational fishing in Western Australia 2015/16, Fisheries Research Report No. 287. Department of Primary Industries and Regional Development, Western Australia.
  19. 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.
  20. Smith-Vaniz, WF and 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.
  21. Steer, MA, Fowler, A J, McGarvey, R, Feenstra, J, Westlake, EJ, Matthews, D, Drew, M, Rogers, PJ and Earl, J 2018, Assessment of the South Australian Marine Scalefish Fishery in 2016. SARDI Research Report Series. SARDI Publication No. F2017/000427-1. 250 pp.
  22. 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.
  23. Thomson, R, Fuller, M, Deng, R and Althaus, F 2016, Data summary for the Southern and Eastern Scalefish and Shark Fishery: Logbook, Landings and Observer Data to 2015 (DRAFT).
  24. 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.
  25. 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.