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Researchers revisit carp hot spots

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• GONE FISHIN’: Dr Dion Iervasi from Austral Research under contract to the Wimmera CMA (right, holding up a large bin of stunned carp) is assisted by CMA member Oakley Gason (holding a large carp) return to the boat ramp on the Yarriambiack Creek on Tuesday afternoon.

Researchers have revisited carp hot spots that are the target of carp removal work to find the pest is retaining a stronghold in Lake Marma, but less so in Warracknabeal and Brim weir pools this week.
Wimmera Catchment Management Authority is tracking the success of its carp removal work from the past two years, with follow-up surveys in Brim, Warracknabeal and Jung weir pools this week.
Carp have been a menace in the Wimmera’s waterways for decades with their feeding behaviour muddying waters and threatening other species.
Wimmera CMA’s removal program aims to improve conditions for native fish and obtain more data on carp numbers and sizes to inform future carp control actions.
Dr Dion Iervasi from Austral Research and Consulting is doing the survey work with an electrofishing boat which uses an electrical current to temporarily stun fish so they can be removed by nets. He is also trialling a multi-beam side-scanning sonar to more effectively spot fish under the water. Depending on the water salinity the voltage used for stunning the fish ranges from 500 to 1,000 volts at up to 26 amps.
His fish harvesting on the Yarriambiack Creek proved interesting with a number of large carp and gold fish being
captured, as well as some smaller yellow belly, which were returned to the creek.
Dr Iervasi also commented on the high quality of the water in the creek, with testing showing a low salinity level of 180 EC.
Wimmera CMA water planning and policy officer Greg Fletcher said this week’s results were mixed.
“Lake Marma in Murtoa has a very large carp population compared to the weir pools and other locations around the region. On the flipside, the surveys found good numbers of Freshwater Catfish in the lake.”
Greg said the surveys indicated that carp removal works had been effective in reducing the carp population in the Brim Weir Pool.
“Results show numbers are reducing over time and still remain quite low, a year on from the last surveys. Dion also discovered large Freshwater Catfish and Golden Perch in the Brim Weir Pool. He has returned the native fish safely to the water to hopefully be caught by more traditional techniques in the future.”