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Australian-first fish screens a big success

Arial shot of conical fish screens in a creek
29 Nov 2019

Early results have found countless numbers of native fish have been saved thanks to Australia’s first irrigation diversion channel screens at Cohuna.

The locally designed and made fish screens were installed in July last year in front of the Cohuna Number 3 Channel regulator in the centre of the town, with funding from the Victorian Environmental Water Holder

Each year, hundreds of thousands of native fish and larvae are lost from the Gunbower Creek and the Murray River system as fish move into irrigation channels.

Once in irrigation channels, the fish are lost to the natural system forever, having a negative impact on breeding and population numbers of native fish, including the Vulnerable Murray cod.

Early monitoring after one full irrigation season has indicated the Cohuna screens are doing their job.

“No Murray cod larvae were detected drifting into the channel during the peak larval drift period after the screen was installed,” North Central Catchment Management Authority (CMA) Project Manager Nicole Bullen said.

“That is extremely important, especially as we were measuring about 160 cod larvae a day going down before the screens were installed.

“That’s potentially thousands of Murray cod a year that are still in the system and contributing to breeding.”

Ms Bullen said there were also benefits to other native fish.

“There were no young-of-year silver perch or Murray cod in the Cohuna Number 3 Channel after the screens were installed, but there was beforehand,” she said.

“There were also decreases in the numbers of smaller fish such as bony bream and the Vulnerable Murray-Darling rainbowfish in the channel.

“Importantly, the screens have now successfully operated for a full irrigation season with no impact to irrigation water delivery and no maintenance required.

“Overall, the project has provided proof of concept of this screening technology in relation to Australian fish species under Australian conditions.”

The project has been acknowledged by industry peers, winning the Innovation in Waterway Management Award at the 2019 River Basin Management Society Awards on November 15.

The RBMS is a representative body for professionals working with land, water and natural resource management in Australia.