This project offers a significant opportunity to enhance tropical and sub-tropical impoundment fisheries in Queensland and other parts of northern Australia, by using new iconic species to diversify the fisheries and attract new anglers to stocked waterways. Accessibility to large pelagic gamefish is not easy for many anglers. Creating access to trevally in impoundments will make such species more accessible to anglers, potentially reduce the pressure on the wild fishery, and offer a unique freshwater impoundment fishing experience in a protected setting. Since trevally will not breed in impoundments, their abundance can be readily managed through stocking rates.

Access to trevally in impoundments is something that anglers want. In 2006, Queensland stocking groups voted trevally as one of the top three ranked new species for development of impoundment fisheries. Published papers indicate trevally are relatively easy to produce, with production methods like those for Barramundi. The other two highly ranked species, Jungle Perch and Mangrove Jack have proved more difficult to produce in large numbers compared to trevallies, and more than 20 years of trying to develop impoundment Mangrove Jack fisheries has achieved only limited success.

Giant and Bigeye Trevally are iconic sportfish, which if stocked, have potential to increase regional tourism. Local governments have already recognised the value of angling tourism in their regions. For example, Rockhampton, Mackay and Cairns Regional Councils have all developed recreational fishing strategies to boost tourist visitation. Townsville City Council is also in the process of opening the Ross River Dam to stocking to develop angling opportunities and attract additional tourists. Trevally will offer an opportunity to create sustained angling tourism to value-add to existing fisheries in the post-pandemic period.

The only way to determine if one or both trevally species can translate into successful impoundment fisheries compatible with existing Barramundi fisheries, is to conduct comprehensive stocking trials using fingerlings and sub-adult fish. The two highest risk factors identified for trevally stocking in large near coastal impoundments are their potential to impact on prey abundance (and therefore carrying capacity) and rare and threatened species. Rare and threatened species are unlikely to be in the impounded waters dominated by Barramundi, but they could exist in impoundment tributary streams. Therefore, knowledge on whether trevally will mostly remain in the impounded waters or will tend to run upstream into tributaries is critical.

This project aims to use stocking trials to evaluate potential stocking risk factors for Bigeye and Giant Trevally, such as relative survival, growth, diet, residency, impacts on prey abundance and rare and threatened species, catchability by anglers at conservative stocking rates, and angler attitudes to and perceptions of the fishery. This project will serve as a useful case study for other diversification options in northern Australia and elsewhere. Without these trials it would be impossible to progress euryhaline trevally species as new fisheries for large, near-coastal impoundments in Australia. This project directly meets the QRAC priority of field-based trials and risk assessment of new species to enhance the value of tropical and sub-tropical impoundment fisheries.