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New monitoring efforts help discover increased numbers of endangered Murray fish

Environmental water releases have contributed to record numbers of the critically endangered Murray hardyhead being rediscovered in the River Murray during a six-month monitoring program.

While there’s only a few known populations of the species remaining in South Australia, recent monitoring efforts recorded more than 75,000 individual Murray Hardyhead, with almost 25,000 fish recorded during a single sampling event.

Water levels were raised at Lock 4 in conjunction with environmental watering of the Katarapko Floodplain near Loxton in the Riverland.

Minister for Environment and Water David Speirs said the monitoring program was possible thanks to environmental water provided by the Commonwealth Environmental Water Holder under the Murray-Darling Basin Plan.

“We know how important the delivery of environmental water is under the Murray-Darling Basin Plan and to have record numbers of critically-endangered fish rediscovered is a great result,” Speirs said.

“We were blown away by the results. At the peak of the investigation our team caught a record number of Murray Hardyhead with almost 25,000 fish recorded during a single sampling event and more than 75,000 individuals caught across the whole investigation.

“In recent months we’ve seen more action to deliver the Murray-Darling Basin Plan than ever before and projects like this show it is working and reconfirm why all Basin jurisdictions need to get on with delivering what’s been agreed for the health of the river and our communities which rely on it.”

Weir success

Department for Environment and Water Project Manager Nathan Creeper said the weir pool raising and environmental watering of the Katarapko Floodplain provided important water flows into the Gurra Gurra wetland complex, home to the endangered species.

“The monitoring has shown a really successful Murray Hardyhead breeding response to weir pool raising,” Creeper said.

“The Gurra Gurra Wetland Complex was heavily impacted by the millennium drought and reduced flows to South Australia and as a result has become more saline.

“The critically endangered Murray Hardyhead have evolved to tolerate saline ecosystems and are now only found in these saline environments where they have a competitive advantage over other fish that are less able to survive at high salinities.”

Creeper said that through this investigation and successful response, the links between the Murray Hardyhead breeding and weir pool raising will inform future management of the population in coordination with weir pool manipulation.

“With floodplain watering at Katarapko planned for 2021 we are planning a potential raising of Lock 4 between July to December,” he said.

“We want to see Murray Hardyhead populations continue to thrive and respond positively to the planned events and hope to build on this year’s successful outcome.”