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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 depleted and the QLD stock is undefined.  

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, Bearham et al. 2020].

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, Pseudocaranx wrighti present in all jurisdictions except Queensland and New South Wales, Pseudocaranx dinjerra only present in Western Australia, and Pseudocaranx sp. ‘dentex’ only present in Queensland [Smith-Vaniz and Jelks 2006, Gomon et al. 2008, Bearham et al. 2020]. 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.

Victoria

Very large quantities of Silver Trevallies (P. georgianus) were landed in Bass Strait using mesh nets up until 1991, however the offshore mesh net fishery is now managed by the Commonwealth and has largely ceased. Since then, landings have been predominantly from seine nets in Gippsland Lakes and Corner Inlet-Nooramunga with a declining catch trend through time as effort with this gear has declined in both fisheries [Conron et al. 2020].

There has been high variability in Silver Trevallies CPUE from seine netting in both the Gippsland Lakes and Corner Inlet-Nooramunga. This is likely to reflect a combination of varying abundance in inshore waters as this species frequents waters offshore, and that it is mostly caught as a by-product while targeting other species. Additionally, there has been very low seine fishing effort in the Gippsland Lakes in recent years and the high catch rate in 2017–18 may not be representative of stock abundance as it is influenced by the catches of a single fisher who landed >2000 kg on multiple occasions. Nevertheless, in both Gippsland Lakes and Corner Inlet, CPUE is above the reference period (1998–2015) average indicating that there are no local signs of depletion [Conron et al. 2020].

The low Silver Trevallies catch in recent years arising from low seine netting effort in Victoria implies that fishing operations are unlikely to cause impaired recruitment under current practices. Indeed, the Gippsland Lakes commercial fishery was closed in 2020 following a licence buy-out so fishing mortality is likely to have reduced further. Given the high catch rates observed in Victorian waters during recent years and low levels of effort, it is unlikely that Silver Trevallies in Victoria are depleted or at risk of becoming recruitment impaired [Conron et al. 2020]. The above evidence indicates that the biomass of this stock is unlikely be depleted and that recruitment is unlikely to be impaired. The above evidence also indicate that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired. 

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

Silver Trevallies biology [Rowling and Raines 2000]

Distribution of reported commercial catch of Silver Trevallies. No catch distribution data are provided for Queensland as Silver Trevallies are not distinguished from other trevally species in relevant Queensland commercial fishery logbooks.

Commonwealth – Commercial (Management Methods/Catch) Data provided for the Commonwealth align with the Commonwealth Southern and Eastern Scalefish and Shark Fishery for the 2018-19 financial year.

Commonwealth – Recreational The Commonwealth 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 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) for more information see https://www.daf.qld.gov.au/business-priorities/fisheries/traditional-fishing

New South Wales – Recreational (Catch) Murphy et al. [2020].

New South Wales – Indigenous https://www.dpi.nsw.gov.au/fishing/aboriginal-fishing

Victoria – Commercial (catch) Silver trevally (Pseudocaranx georgianus) is not differentiated from other trevallies caught in Victorian commercial fisheries.

Victoria – Indigenous A person who identifies as Aboriginal or Torres Strait Islander is exempt from the need to obtain a Victorian recreational fishing licence, provided they comply with all other rules that apply to recreational fishers, including rules on equipment, catch limits, size limits and restricted areas. Traditional (non-commercial) fishing activities that are carried out by members of a traditional owner group entity under an agreement pursuant to Victoria’s Traditional Owner Settlement Act 2010 are also exempt from the need to hold a recreational fishing licence, subject to any conditions outlined in the agreement. Native title holders are also exempt from the need to obtain a recreational fishing licence under the provisions of the Commonwealth’s Native Title Act 1993.

Tasmania – Indigenous (management methods) In Tasmania, Indigenous persons engaged in traditional 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. 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” details application procedures for issuing a UIC.

Commercial catch of Silver Trevallies - note confidential catch not shown

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