Carp cull plan has a catch, experts warn

Carp cull plan has a catch, experts warn


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Barnaby is angling for a big solution, but concerns worry experts.

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THE $15 million Murray Darling Basin-wide carp cull initiative is running full stream, with Water Minister Barnaby Joyce this week appointing a national co-coordinator to manage deployment of a carp herpes virus, but river experts warn the plan won’t work.

Mr Joyce said government aimed to have plans in place for a release of the biological control virus by the end of 2018, which he said could potentially nearly eradicate carp in the vast river system.

“In particular we are assessing whether the virus will effectively deliver a significant reduction in carp impacts to achieve our goal of a 95 per cent reduction in carp by 2045 at an acceptable cost,” he said.

Environmental scientist and fisheries expert, Matt Barwick, dubbed the carpinator by Mr Joyce, will lead the National Carp Control Plan. 

Dubbed “the rabbit of our waterways” by Mr Joyce, carp are estimated to have a total biomass of up to two million tonnes across the Murray Darling Basin and deliver a $500m economic hit, with lowered irrigation water quality and damage to wetlands.

Carp also compete with native fish for food, eat aquatic plants, and reduced water quality and undermine banks by stirring up sediment when feeding.

But while University of Canberra research fellow, Dr Peter Unmack, acknowledged the negative impacts of carp, he said eradicating an established species is extremely difficult.

Dr Unmack, who has two decades of experience working in the Basin, said disposal of carp carcases is a particular concern, as decaying fish would pile up from the first week the virus was release, which would de-oxygenate water and hurt native fish stocks.

"River flow in the Murray Darling has gone from extremely variable to extremely reliable which makes it an ideal environment for carp, if it remained variable native fish would flourish and carp would not do as well," Dr UNmack said.

"You would need a lot of people in boats with nets scooping up dead fish."

​Griffith University, director of Australian rivers institute, Dr Stuart Bunn agreed with Dr Unmack, that the virus is no silver bullet. 

“There’s short term consequences such as water quality and then long term consequences like what takes up the 90 per cent biomass that the carp once held,” Dr Bunn said.

“The river won’t necessarily go back to how it was before,when carp go”

Dr Unmack says that complete eradication of carp is impossible with the Murray Darling being 13.8 per cent of the total area of mainland Australia, the scale is simply too large, even on a much smaller scale it is still very difficult to fully eliminate carp.

"The population will bounce back but probably never as abundant as before," similar to introduction of myxomatosis in rabbits in the 1950s.

Dr Bunn said “we can control numbers, but we wont completely get rid of carp,” Dr Bunn said.

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