Fish recovery good news for Murray River
THE RESURGENCE OF CRITICALLY endangered native fish in the Murray Darling river system may be an indication that the stressed ecosystem is beginning to recover.
The southern purple-spotted gudgeon (Mogurnda adspersa), which inhabits the Lower Murray region in South Australia, and the river blackfish (Gadopsis marmoratus), which is found in the eastern parts from Queensland to Victoria, were on the verge of extinction several years ago. Concerted efforts by governments and conservationists have seen populations of both fish bounce back, and recent rains has brought much-needed health back to the Lower Murray.
“The conservation effort, along with the return of freshwater inflows due to winter rains, has gone a long way to help ensure the river blackfish will survive and thrive in the River Murray system,” says Paul Caica, South Australian Minister for Environment and Conservation.
Murray Darling conservation
Surveys between 2007 and 2009 of the river blackfish found very few adults and no evidence of breeding activity. “There [had] been no sign of this native freshwater species in the River Murray for 50 years and only small patches remaining in the Lower Lakes tributaries, including the Bremer River” says the minister.
But a recent survey of the Bremer River catchment in South Australia found 85 juvenile river blackfish. Since 2007 a collaborative conservation effort between the South Australian government, conservationist and research groups has been underway The joint project oversaw the installation of and an aeration system to sustain the dwindling number of river blackfish during the drought.
Earlier this year numbers of the critically endangered southern purple-spotted gudgeon were found to be healthy and improving in the Lower Murray. Last year 200 of the gudgeons bred in captivity were reintroduced into Paiwalla Wetland, a drought-proof refuge near Murray Bridge in South Australia.
Native Fish Australia (NFA), a not-for-profit research and conservation organisation, has led the breeding program with two established hatcheries for the fish.
“The program has so far been a success,” says Dr Michael Hammer, coordinator of NFA’s captive breeding program. “Another 75 fish bred in our hatcheries [were] released this weekend, while a further five reproducing sites, stretching from the Lower Murray to Victoria, are planned for the future.”
NFA is assisting with a similar breeding program for the Yarra pygmy perch being coordinated by the SA Department for Environment and Natural Resources.
The southern purple-spotted gudgeon (Credit: Gunther Schmida/MDBC)
Long term prospects for Australian fish in the Murray River
Federal minister for Sustainability, Environment, Water, Population and Communities Tony Bourke announced in March support for three projects to improve the health of the River Murray environment in South Australia. State and federal governments will spend $9.2 million in South Australia aimed at restoring significant wetlands and floodplains. The initiative is part of South Australian Government’s $100 million Riverine Recovery Project.
SA Research and Development Institute (SARDI) is currently leading an extensive research project aimed at improving the long-term health of the River Murray system. “This project is a unique opportunity to undertake time-critical ecological investigations, measuring how biological systems respond and recover when water is restored to the system after a long period of drought,” says lead scientist Dr Qifeng Ye.
Low water levels in the Murray system led to the salinisation – increased salt content – of freshwater habitats. Improved inflows in the river system, as well as continued efforts by conservationists and government, should further aid the recovery of other endangered fish such as the Murray hardyhead, congolli and Yarra pygmy perch, NFA’s Michael says.
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