In an effort to rescue the Yarra pygmy perch from the precipice of extinction, a dedicated group of South Australian ecologists has taken on a third mass release of these diminutive native freshwater fish into the River Murray.
The endeavour comes after two previous attempts to save the species faltered, raising hopes for a successful revival.
“I’m really hopeful this latest effort to rehabilitate the Yarra pygmy perch will be successful,” Minister for Climate, Environment and Water, Susan Close, says.
“It is vital for the health of the River Murray and the Coorong that we have a diverse range of species.
“These dedicated ecologists have worked for 15 years to bring this species back from the brink and I’m looking forward to seeing the results.”
Approximately 7,000 Yarra pygmy perch have been reintroduced into the river at three strategic sites near Hindmarsh Island, with the aim of re-establishing their population in the wild. These efforts follow a drastic decline in numbers attributed to the devastating impact of the Millennium Drought, which pushed the species to critical levels in 2008.
The Yarra pygmy perch, known for its petite size of just four centimetres, thrives in still or slow-moving waters abundant in aquatic vegetation, which provides essential protection, food, and breeding habitat. Although first spotted at Hindmarsh Island in 2002, these tiny fish have a historical presence dating back to the late 19th century in various parts of southeastern Australia.
Driven by concern over their dwindling numbers, a coalition of aquatic ecologists, led by Dr. Michael Hammer, initiated efforts to safeguard the species. Their approach involved rescuing the remaining fish from the river and fostering breeding in surrogate dams across private properties in regions spanning from the Adelaide Hills to Barossa and Fleurieu.
After fifteen years of concerted efforts and two previous attempts, ecologists remain cautiously optimistic, citing advancements in understanding habitat dynamics and water flow as key to enhancing the prospects of survival.
Techniques such as soft release structures, submerged in the river to allow for acclimatisation before release, have been implemented to bolster the species’ chances of enduring in its natural habitat.
Encouraging signs have emerged from recent monitoring efforts, with a notable number of Yarra pygmy perch successfully recaptured and reintroduced into the river. This positive development underscores the importance of ongoing collaborative efforts in conservation.
“We have a much better understanding of the habitat, vegetation and flow conditions that Yarra pygmy perch favour and thanks to the generosity of private landholders who provide their dams as surrogate refuge breeding sanctuaries, we have high numbers of beautiful healthy fish to release,” Dr Sylvia Zukowski, Senior Aquatic Ecologist, Nature Glenelg Trust, says.
“So, we’re more confident that these latest releases will survive long enough to breed the next generation.
“This is great news, and hopefully will be the start of the end of the extinction of the Yarra pygmy perch in the region.”
The restoration project represents a collaborative endeavour involving various stakeholders, including the Nature Glenelg Trust, Murraylands and Riverland, Hills and Fleurieu landscape boards, the University of Adelaide, Flinders University, and the Ngarrindjeri Aboriginal Corporation.
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