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carp-removed

Carp removed

Carp removed

ACOUSTICS TO HARVEST CARP FROM GLENELG RIVER

Using audio equipment isn’t the first thing you think of when looking for carp populations in a river, but the advancement in technology has seen more than 3.2 tonnes of this pest species removed from the Glenelg River using this odd fishing method recently.

In partnership with Austral Research and Consulting, OzFish Unlimited and K&C Fisheries the Glenelg Hopkins CMA has been using high tech techniques to locate and remove schools of carp populations in the upper Glenelg River near Balmoral.

Prior to the most recent lockdown restrictions, the group effort removed 200kg of carp. This is on top of three tonnes of carp being removed in an OzFish Unlimited-led removal earlier this year.

Glenelg Hopkins CMA project officer, Stephen Ryan said an acoustic tracking program provided solid information to help to find carp schools which then allowed electrofishing techniques (which stun and capture the carp) to be used to remove fish from the river. Stephen said the combination of finding schools, electrofishing and continued monitoring was the best way of keeping a lid on carp populations in the Glenelg.

“We’ve found over the years that electrofishing is the most cost-effective way of removing carp.”

“We apply a current to the water that brings the fish to the surface and we can easily capture large numbers and dispose of them.

“With nets you might get one or two fish but using this method you can get up to a hundred in one area, so it’s much more effective.”

Mr Ryan said keeping a lid on carp numbers was essential for the health on the Glenelg River.

“There are good native fish in the river, and by removing carp it keeps these fish populations fit and healthy as the carp outcompete the native fish and muddy the water,
which negatively impacts native species,” he said.

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This year’s carp removal efforts used techniques which were developed during the Glenelg Hopkins CMA Judas Carp acoustic tracking project undertaken four years ago.

It was found in the Judas Carp project that carp in the Glenelg River showed they tend not to move during the colder months. Therefore, acoustically locating, and then targeting fish aggregations in the cooler months, had the greatest impact on local carp numbers.

Using that acoustic technique, six sites were selected in June for carp removal, with two having significant numbers of fish present.

From these two sites, Pine Hut and Fulham Reserve, large aggregations were found and a total biomass of 3 tonne of carp were removed.

A return trip in August was scheduled to assess the impact the harvest had on carp numbers.

“Amazingly only 200 kilograms of carp were found and removed during the second trip,” Stephen said.

“It shows that by removing those really big numbers in the middle of winter did have an impact.”

The Glenelg Hopkins CMA continues to pursue funding for carp control operations.

“Partnerships like the one with Austral research and Consulting, OzFish Unlimited and K&C Fisheries show working together for a common goal provides positive environmental, recreational and commercial outcomes.”

This year’s activities were funded by OzFish and Austral Research and Consulting.

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