Australia’s plan to eradicate carp using the herpes virus is ‘serious risk to global food security’

PUBLISHED : Friday, 24 February, 2017, 3:21pm
UPDATED : Friday, 24 February, 2017, 10:59pm

Scientists in Britain have raised concerns about Australia’s A$15 million plan to release a herpes virus in the nation’s largest river system to eradicate carp, saying it poses a serious risk to global food security, could cause “catastrophic ecosystem crashes” in Australia, and is unlikely to control carp numbers long term.

[Laboratory tests] cannot rule out the possibility of cross-infection
Scientists

In a letter published in the Nature Ecology and Evolution journal this week, University of East Anglia researchers Dr Jackie Lighten and Prof Cock van Oosterhout say the “irreversible high-risk proposal” could have “serious ecological, environmental, and economic ramifications”.

The Australian government allocated A$15m in the 2016 budget to a national carp control plan, centred around a plan to release the koi herpes virus into the Murray-Darling river system to kill common carp, or Cyprinus carpio.

It followed extensive research by the CSIRO, which conducted seven years of tests to ensure that native fish, birds, amphibians, and other species in the river system could not contract the virus.

Lighten and van Oosterhout say the use of the carp herpes virus should not be compared to the release of the myxomatosis virus to control the rabbit population, arguing: “compared with the biocontrol of terrestrial vertebrates, the biocontrol of large, highly fecund aquatic animals such as carp adds novel risks.”

They argue that laboratory tests “cannot rule out the possibility of cross-infection” and that the virus will have “an enormous evolutionary potential” once released in the wild, and could evolve to attack other species.

They also say that releasing a notifiable disease that attacks the most commonly-farmed fish in the world could impact the global food supply, and that the oxygen loss caused by millions of tonnes of rotting carp killed by the virus in the Murray Darling Basin could “lead to catastrophic ecosystem crashes”.

“[Koi herpes virus] is a highly efficient killer of common carp, and since its initial outbreak and rapid global spread in the 1990s it has caused millions of dollars of losses to the carp aquaculture and angling industries,” van Oosterhout said. “Carp is one of the most farmed fish in the world and an important source of protein in lower to middle income countries, so is vital to food security.”

The coordinator of the National Carp Control Plan, Matt Barwick, said the concerns raised by Lighten and van Oosterhout were already being examined by the Fisheries Research Development Corporation.

Barwick, who has been dubbed “The Carpinator” by the agriculture minister, Barnaby Joyce, and is an enthusiastic supporter of the project, has been given two years to develop the carp control plan and provide a detailed risk assessment to the federal government.

That process will include further testing to ensure the virus does not affect other species, and Barwick said there was no evidence from countries where the virus was already present that it had evolved to attack other species.

“This virus is now found in almost every river and lake system in Japan, and in another 32 countries,” he told Guardian Australia.

“Despite that, the only species that this virus has been detected to cause disease in is the common carp. In these countries they are sharing a waterway with other species of koi, very closely related to the common carp, and those other species haven’t contracted the virus.”

Barwick said he did not believe it would threaten global food security, because all the countries that relied on carp as an aquaculture species already had the virus. Dealing with mass carp deaths after the virus’s release was a significant problem, he said.

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Carp was introduced to Australia in the 1800s and makes up 90 per cent of the fish biomass in the river system, to the devastation of native fish species and the general health of the waterways.

It is not farmed for food purposes in Australia and cannot be traded with other countries, due to Australia’s tough biosecurity laws. There is some commercial farming of ornamental koi, which are the same species as the common carp and are therefore susceptible to the virus.

Latrobe University senior ecology lecturer Dr Susan Lawler, who is based on the Murray River, said Lighten and van Oosterhout “don’t understand the Australian perspective”.

“The reason they are terrified of it going wrong is because they don’t understand how terrified we are that all the native fish in Australia are going to die off because of carp,” Lawler said. “There’s an ecological disaster going on right now.”

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Lawler said all of the concerns raised in the article, including that the virus could evolve to attack other fish, or that fish could die off in a eutrophic event caused by millions of dead carp, presupposed that native fish were not already dying. “I am not worried about it because at the moment these fish are dying anyway.”

She agreed that the virus would not kill the entire carp population, and that their numbers would recover, but said that did not mean it wouldn’t be a long-term solution. “In my mind, 90 per cent carp biomass reduced to 50 per cent would be a long-term solution.

Modelling done by the national carp research project anticipated the carp population would recover to between 30 per cent and 40 per cent of its current numbers after suffering the first mass mortality from the virus. Barwick said secondary control measures would be introduced to keep numbers down.