Australian fishers, farmers, and environmentalists have taken enough crap from carp—and they’re calling for deadly measures. According to the Sydney Morning Herald (SMH), they’re aiming for a virus to be released that will wipe out most of the carp population.
Carp is a species that was introduced to Australia around 1859, although they didn’t really take off in terms of population until the early 1900s. Since then, they have become a growing problem, as they feed on the bottoms of rivers, making the water cloudy. This harms native fish’s ability to reproduce, and also stunts plant growth. Besides this, carp also are direct competitors with other native species for habitats, and have even been known to feed on their young.
Because of this, there have been huge declines in the populations of native fish across freshwater ecosystems—especially in the Murray-Darling Basin, an inland waterway that encompasses around one-seventh of Australia’s landmass.
Now, some of Australia’s largest fishing, farming, and environmental groups—such as the Australian Conservation Foundation, National Farmers’ Federation, Invasive Species Council, and the National Irrigators’ Council—are calling for carp annihilation.
Koi herpes virus to annihilate crappy carp
Their hope rests on the koi herpes virus (KHV), a DNA-based virus that is of the same family as (you guessed it) herpes simplex virus. The first recognized case of the virus occurred in the UK in 1996, and it has been known to kill up to 100 percent of all carp while ignoring other fish species—which would have obvious benefits.
According to Allan Hansard, the head of the Australian Recreational Fishing Foundation, should the virus prove effective, inland waterways would return to almost the same condition they were in before the carp were introduced.
“People say inland waterways like the Murray-Darling used to be clear, wouldn’t it be great to see that?” Hansard said to the SMH.
Long-studied, clean bill of health
The Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia’s national science agency, has been testing the koi herpes virus since 2007. The head of the research project, Ken McColl, told the SMH that it could potentially kill 70 to 90 percent of carp.
McColl also said that the research has shown no ill effects in regards to the native fish, and that testing done on invertebrates, mammals, and birds showed no negative results either. In Europe, the virus has not spread to other species or humans either.
“It’s potentially a white knight for removing, or at least reducing, carp numbers significantly in the Murray-Darling Basin,” McColl said.
Didn’t they do this in a Michael Crichton book?
Of course, killing off a species that accounts for 90 percent of the fish biomass in the Murray-Darling Basin would be pretty messy; millions of tons of dead fish would have to be cleaned from rivers and other freshwater regions. The groups proposing the virus’ release have concluded that community engagement and clean-up efforts would have to follow the release.
But more than that, herpes viruses have spread from animals to humans before—from mice and macaques. While the koi herpes virus currently shows no signs of making this leap, mutations could theoretically make it possible.
Further, while koi herpes virus mainly infects carp, it also infects and kills koi—meaning anyone with an ornamental pond is at risk of losing their fish. The route of transmission here would be more indirect, as transmission requires things such as direct contact with an infected fish; with fluids from infected fish; or contact with water, mud, or other vectors (like birds) that have come into contact with contaminated systems. Still, the risk is there, and koi can be very expensive.
But perhaps the last problem: While there is a vaccine for the virus, it is not approved for broodstock (breeding fish) or fish smaller than 100 grams—meaning baby fish are out of luck. Worse, there is no treatment for koi herpes virus, so if something goes wrong, there is no way to stop it. This could especially become a problem since the carp that survive the virus may become carriers, spreading it further throughout the ecosystem.
A spokesman for Australia’s Environment Minister, Greg Hunt, told the SMH that any proposals to help eradicate carp would be considered “exclusively on the basis of science, and against the most rigorous standards.”
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Feature Image: Thinkstock
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