The importance of off-river areas for fish in the mid- and lower Lachlan catchment of the Murray–Darling Basin, Australia: three case studies

Context There is increasing concern regarding the integrity of freshwater ecosystems at a global scale, and Australia’s Murray–Darling Basin is an area where the impacts of river regulation and invasive species are well-known and documented. However, broad-scale assessments have generally occurred in main-channel habitats. Aims The study considers endangered species and fish communities in off-river habitats in a specific Murray–Darling Basin catchment (the Lachlan) and aims to demonstrate that these wetlands and creeks may be important ecological areas in lowland river catchments. Methods The data are drawn from a large number of studies conducted since 2017; however, the fish-sampling methodology has remained constant throughout (large and small fyke nets set overnight). Key results Populations of endangered species such as olive perchlet (Ambassis agassizii) and freshwater catfish (Tandanus tandanus) persist at certain off-river locations within the Lachlan catchment, and large water storages appear to provide suitable habitat for sustaining resident populations of a broader range of native species. Conclusion Off-river areas play important roles within inland riverine systems, and research within and management of these often isolated habitats may pay ecological dividends, especially given the overall decline of freshwater systems worldwide.