*

Silver Trevallies inhabit estuarine and coastal waters throughout southern temperate Australia. Of the seven separate Australian stocks, three (in WA, SA and TAS) are sustainable. Stocks in QLD and VIC are undefined. The Commonwealth and NSW stocks are in review, and will be updated once complete.  

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 a 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

IIn Victoria, 100–300 t of Silver Trevallies were landed in Bass Strait using mesh nets from 1978–79 to 1991–92; after which the offshore mesh net fishery has been managed by the Commonwealth. Since this transition, commercial landings have been a by-product predominantly from seine netting targeting other species in Corner Inlet-Nooramunga, and previously in Gippsland Lakes, and Port Phillip Bay with a declining catch trend through time as effort with this gear reduced until the latter two fisheries were closed two years ago following licence buy-outs [Bell et al. 2023]. Landings have been around 50 t or less for the last ten years, with the lowest on record of 8.4 t in 2021–22. Silver Trevallies are targeted as well as caught as by-product by recreational fisheries throughout the state but there is no quantitative information on recreational landings as they are rarely encountered in creel or angler diary monitoring programs.

There has been high variability in the CPUE of Silver Trevallies from seine netting in Corner Inlet-Nooramunga, the only current source of reliable data. This variability is likely to reflect varying abundance in inshore waters as Silver Trevallies use seagrass beds in the inlet as nursery grounds. Catch rates, while variable, peaked between around 1998 and 2008, but have subsequently declined to approximate the levels observed prior to 1998. However, the large interannual fluctuations in nominal CPUE indicate that the actual trend is uncertain [Bell et al. 2023].

The low landings of Silver Trevallies in recent years arising from low seine netting effort in Victoria implies that fishing operations within Corner Inlet-Nooramunga are unlikely to be causing impaired recruitment under current practices. Landings will likely remain low statewide for the Victorian managed fishery due to the closure of most bay and inlet commercial fisheries and because commercial effort in Corner Inlet-Nooramunga is generally not targeted towards Silver Trevallies. As Silver Trevallies move sporadically into Corner Inlet-Nooramunga from Bass Strait from year to year, the performance of the stock is linked to the status of the Commonwealth fishery, and potentially other fisheries in south-eastern Australia. In this context, it is unlikely the commercial fishery in Corner Inlet-Nooramunga and the recreational take statewide are causing substantial depletion or, individually, placing the stock at risk of becoming recruitment impaired [Bell et al. 2023].

Although, the above evidence indicates that the current level of fishing mortality in Victoria is unlikely to be causing the stock to become recruitment impaired statewide, there is uncertainty about stock status given the extent of the stock is currently unknown, but likely to comprise a component of the adjacent Commonwealth, and potentially even New South Wales, jurisdiction(s).On the basis of the evidence provided above, Silver Trevallies in Victoria is classified as an undefined stock.

Silver Trevallies biology [Rowling and Raines 2000]

Distribution of reported commercial catch of Silver Trevallies. 

Commonwealth – Commercial (Management Methods/Catch). Data provided for the Commonwealth align with the Commonwealth Southern and Eastern Scalefish and Shark Fishery for the 2021–22 financial year.

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 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

Queensland – Recreational Fishing (Catch). Data with high uncertainty (Residual Error >50 %) have been excluded and listed as unknown. More information is available at: https://www.daf.qld.gov.au/business-priorities/fisheries/monitoring-research/monitoring-reporting/statewide-recreational-fishing-surveys

Queensland – Commercial (Catch). Queensland commercial and charter data have been sourced from the commercial fisheries logbook program. Further information available through the Queensland Fisheries Summary Report https://www.daf.qld.gov.au/business-priorities/fisheries/monitoring-research/data/queensland-fisheries-summary-report

New South Wales – Recreational (Catch). Murphy et al. [2022].

New South Wales – Indigenous (Management Methods). (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. For details, see the policy document 'Recognition of Aboriginal Fishing Activities” (https://fishing.tas.gov.au/Documents/Policy%20for%20Aboriginal%20tags%20and%20alloting%20an%20UIC.pdf).

Commercial catch of Silver Trevallies - note confidential catch not shown

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