Carp in cross hairs

Revelations of a growing presence of carp in one of the Wimmera’s top angling lakes is set to add weight to a push for a national introduction of a speciesspecific virus to tackle the pest fish.

They might also strengthen an argument that the Wimmera Basin, home to a closed river system, should be among potential trial target areas for a release of the virus.

Wimmera Catchment Management Authority, in response to reports of a growing catch rate of the species in Toolondo Reservoir, is awaiting results of DNA water sampling to assess the extent of the carp spread in the lake.

It will use its findings to develop a carp-control plan for Toolondo using traditional methods and will also forward the information for inclusion in a National Carp Control Program, NCCP.

Project leaders are working on the NCCP, which will outline ways of tackling noxious carp to improve the quality of Australian waterways. One potential solution is the possible release of the carp virus cyprinid herpesvirus-3, through a $15-million Fisheries Research and Development Corporation plan on behalf of the Federal Government.

As part of the plan, the NCCP is co-ordinating a national research program to understand how best to manage the potential release of the virus to control carp species and community attitudes and opinions involving the concept.

The virus concept has attracted widespread support in Australia, but also international fears that the disease might jump the border and threaten an important worldwide fish resource.

Wimmera CMA chief executive David Brennan said an increasing carp catch rate at Toolondo, renowned as a trophy trout, redfin and yabby fishery, represented an added frustration in a battle to protect environmental water quality.

“There had been a growing number of reports about carp in the lake – I even caught one myself – so we went out and did some EDNA sampling,” he said. “We took nine samples in three different ponds and they are currently getting analysed at a lab in Melbourne. We expect results in the next few days.

“Carp might have been in the lake before, but perhaps not at the level we suspect they are now.

“As soon as we get an understanding of the carp presence we will consider control measures and perhaps tackle them with electrofishing while they are schooled up over the winter months.”

Carp, which have a reputation for displacing native or favourable exotic species and creating turbid conditions, have become the dominant fish species in the Wimmera River system.

But some upper catchment lakes, such as Bellfield, Wartook, Fyans and Lonsdale remain free or relatively free of the fish.

EDNA sampling, a developing technology, involves analysing water samples for cells shed by aquatic creatures and helps provide a snapshot of waterway life.

Wimmera CMA has long been involved in the exploration of carpcontrol measures and has strongly backed the release of a carp-specific virus in the region, pending appropriate and in-depth duty-of-care research and process.

“We’ve been enthusiastic about the potential benefits the release of the virus might have for the region. But at the same time we want to make sure the science is right and to not create any negative outcomes,” Mr Brennan said.

“The Wimmera is keen to stay at the forefront of the carp-eradication project and to provide any information needed for a positive result.

“What we’re understanding is that the carp virus, if released, isn’t going to be a silver bullet and there is going to be a need for a range of other control processes and techniques.”

NCCP national co-ordinator Matt Barwick said extensive work was essential before a decision was made on whether a carp virus was the best option to control the fish.