In early 2020, extreme drought created unprecedented dry conditions in perennial streams in the mountainous headwaters of the Darling River catchment. Spring Creek provides a thermal and ecohydrological refuge for a unique community of cold-water specialists including river blackfish (Gadopsis marmoratus), which are relics of past colder, wetter climates. Low flows, increased water temperatures, heatwave and bushfires, along with longer-term climate change and land use impacts, combined to create extreme risks to this ecosystem. It is isolated by vast warm-climate areas uninhabitable for upland specialist species, meaning natural recolonisation is not possible and local extinctions would be permanent.
A salvage operation carried out under the Native Fish Recovery Strategy collected blackfish from this last known habitat in Queensland, and created an insurance population, along with mountain galaxias (Galaxias olidus) and spiny crayfish (Euastacus sulcatus). A primary aim was to develop ark population methods for these macrofauna as a community rather than as single species. The salvaged fish and crayfish were kept in aquaculture and observed to determine the effects of these different housing strategies on survival, growth and behaviour.
Patchy but significant late summer rain ultimately maintained water levels at Spring Creek, and surveying in June 2020 showed that the wild population of blackfish had survived. Because of this, and the risk of disease transmission and increased competition, reintroduction of the captive fish was not appropriate. Instead, the captive blackfish were released into a new location within the historical range of the species, Adjinbilly Creek, to help meet objectives for range expansion under the Murray-Darling Basin Plan. If it establishes successfully, a second population in the area may also act as an insurance policy for the Spring Creek population, much like the captive population did, in the increasingly likely case that catastrophic climate conditions return in the future.