Marine heatwave forecast triggers rapid response strategy for critically endangered red handfish

Abstract As climate change drives increasingly frequent and severe climatic extremes, effective strategies to prevent extinction of threatened species are urgently needed. Interventions enabling species to survive acute stress may buy time to address other threats and identify long‐term refugia. For the Critically Endangered red handfish ( Thymichthys politus ), forecasts ahead of the 2023/2024 El Niño indicated a high risk of marine heatwaves (MHW). An expert workshop identified these forecasted extremes (>20 or +~3°C) as a severe threat, triggering an emergency rescue to temporarily remove individuals from the wild. Following commonwealth, state and institutional approvals, 25 fish were captured in January 2024 and held in captivity for 3 months. During this period, in situ water temperatures exceeded records, including 80 days more than 2°C above the long‐term mean summer temperature (~17.5°C). Three fish died in captivity and four adults were retained in a captive breeding program, while the remaining 18 individuals were returned after the MHW subsided, with post‐release survival confirmed after 2 months. This represents Australia's first pre‐emptive rescue of a protected marine species and highlights the importance of proactive, adaptive conservation to strengthen capacity in safeguarding threatened species during environmental extremes and long term climate change impacts.