Management of many Australian freshwater recreational fisheries involves supplementation of existing populations or attempts to establish new populations through the release of fingerlings. Conservation management of threatened freshwater species also relies heavily on the release of fingerlings to establish new populations. Australian and overseas studies have repeatedly demonstrated that fingerling stockings succeed in a limited number of cases and often the success of these programs is difficult to evaluate with conventional approaches. The factors and stocking strategies that can enhance the chances of fingerling stockings being successful are only just starting to be investigated in Australia (see FRDC Project 1998/221 “Impoundment stocking strategies for eastern and northern Australia”).

This project provides an opportunity to explore the possibility of re-establishing adult cod populations through seeding with fewer but much larger individuals (not fingerlings). The research has particular relevance to Australian freshwater cods as apex predators that may serve as indicators of river system health. Additionally, the study species, Trout Cod is Australia’s most imperiled cod species. It was once an important recreational species and a component of the inland commercial fishery of the Murray-Darling Basin. Today extensive efforts to recover the species and establish new populations remain limited by our lack of understanding of what happens to stocked individuals during sub-adulthood.