Carp virus is still on the agenda, DAFF says

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A carp virus is still likely to be released into the River Murray to bring the pest fish under control, the federal Department for Agriculture, Fisheries and Forestry says.

Nine years have passed since the federal government first proposed using a herpes virus to reduce the population of the introduced species, much like the calicivirus which had targeted feral rabbits in the 1990s.

Thinning out the carp would improve water quality and give native fish a chance to thrive.

Now work is starting on a fresh round of research that will address some of the unanswered questions in the National Carp Control Plan:

• Are we certain that the virus cannot jump species?
• What impact would a release have on sensitive environments?
• How would it spread once it was released?
• What would be the best way to clean up all the dead carp?

Andrew Pearce, DAFF’s director of invasive species research and development, told Murray Bridge News that the virus idea had shown promise.

“At the moment … the information we’ve generated through the research process is consistent with the virus being suitable for use in the system to achieve the objectives we want to achieve,” he said.

“There’s nothing that has emerged to say it’s not a good idea.”

The most common concern brought up by members of the public, he said, was how thousands of tonnes of dead fish could be cleaned up after the virus’ release.

There are about four tonnes of carp for every hectare of water along the Lower Murray – that works out to about one fish per 15 square metres.

“They stink, and the decaying bodies would (have an) impact on water quality and a detrimental effect on native species,” he said.

“That’ll be a big focus … through the epidemiological modelling.

“What can we do to reduce the risk of a big, unmanageable spike in carcasses?

“That may involve (thinking about) the timing of the release of the virus in terms of season, macro-climatic circumstances, which parts of the river to release it in and what mechanisms we have on hand to physically remove carcasses, or to re-oxygenate the water.”

Researchers will spend the next two years answering those questions.

An updated plan will be presented for regulatory approval after that – a process likely to take another year or so.

Even a field trial of the virus, a test release in an isolated area, was not likely to happen until about 2028.

A decision about whether to take that step, or proceed with a large-scale release, will be up to the state and federal agriculture ministers.

Any decision will rely on the advice of DAFF; the Department for Climate Change, Energy, the Environment and Water; and the Australian Pesticides and Veterinary Medicines Authority.

The department appreciated that people in some parts of the Murray-Darling Basin were getting impatient, Mr Pearce said, but it was important not to be reckless.

“This is a unique circumstance,” he said.

“(Releasing a virus to target pest fish) hasn’t been done anywhere in the world.

“It’s important to get as much clarity on those aspects of concern … as possible.”

• More information: Visit www.agriculture.gov.au or call 1800 900 090.