Swan galaxias (Galaxias fontanus) is a threatened freshwater fish endemic to Tasmania with a naturally restricted distribution, making the species vulnerable to stochastic events and localised threats. The species has experienced substantial range contraction and population fragmentation, with introduced brown trout (Salmo trutta) forcing it into isolated marginal habitats. These populations are increasingly exposed to climate change impacts, including more frequent droughts that reduce stream flows and extreme flood events that may affect recruitment and survival of early life stages. To increase population redundancy and reduce extinction risk, a conservation translocation program was undertaken to establish three refuge populations within catchments in eastern Tasmania.
Recipient streams were selected using a multi-criteria assessment incorporating habitat suitability, invasive species risk and climate resilience. Hydrological characteristics associated with healthy extant populations were used to develop habitat suitability models, while targeted surveys confirmed the absence of introduced predatory fish. Climate and streamflow projections under future climate scenarios were used to identify streams with the greatest likelihood of maintaining suitable habitat over the long term. DNA sequencing characterised genetic variation among extant populations and informed source population selection. One hundred and eighty individuals from five genetically diverse source populations were translocated to three fish-free headwater streams.
Monitoring demonstrated high post-release survival and successful establishment in all recipient streams. Following establishment of two populations in autumn 2023, recruitment was detected within 12 months, with juvenile fish confirming successful reproduction. A third population was established in autumn 2025 with recent monitoring detecting translocated fish and young-of-year recruits. These results demonstrate that habitat and climate-informed conservation translocation can successfully establish refuge populations of Swan galaxias and contribute to the long-term recovery and resilience of this threatened Tasmanian endemic.