British scientists have raised public concerns about Australia’s $15 million plan to wipe out carp populations using a virus. 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”.

Carps are causing massive problem in the Australian environment. Image credits: Type17 / Wikipedia.

Australia has a poor record of conservation of native fauna. In its modern history, the country has suffered environmental disaster after environmental disaster. As soon as Europeans started settling the island, problems started. Colonists brought rabbits and rats which thrived in the Australian environment and spread way beyond what anyone predicted. Then, they brought in cats to “settle the problem” — but that’s not how an ecosystem works. Cats also spread way beyond expectations, and the environmental issues cascaded more and more. To this day, Australia is fighting an uphill battle against invasive species.

Among those invasive species, there’s also the inconspicuous carp. While neighboring Tasmania was successful in clearing out the carp from their Lake Crescent using conventional measures, Australia’s efforts have largely been fruitless. So Australia devised another (environmentally questionable plan): use the carp-specific koi herpes virus to wipe out the population. The minister for industry, innovation and science, Christopher Pyne, the deputy prime minister, Barnaby Joyce, and the minister for the environment, Greg Hunt, are part of a task force to oversee and implement this $15 million plan.

“The common carp is a nasty pest in our waterways and makes up 80% of fish biomass in the Murray Darling Basin,” Pyne said.

“Anyone who loves the Murray knows what damage the carp have caused to the river environment over many years. The Invasive Animals Cooperative Research Centre and the CSIRO have made significant progress evaluating a viral biological control agent, we know that it works, we know it’s completely safe, now we need to plan the best way to roll it out.”

It’s not the first time something like this would happen. In 1991, a strain of Calcivirus was imported to Australia under strict quarantine conditions to research the safety and usefulness of the virus if it was used as a biological control agent against Australia and New Zealand’s rabbit pest problem. Testing did take place for a few years, but in 1995, the virus escaped quarantine and subsequently killed 10 million rabbits within 8 weeks of its release. Even though the virus was released by accident, its effects were regarded as a “success” — though there’s something inherently morbid about seeing 8 million rabbit fatalities as a success.

But Lighten and van Oosterhout say the use of the carp herpes virus should not be compared to that situation. They argue that applying the same strategy to marine creatures adds new risks: “compared with the biocontrol of terrestrial vertebrates, the biocontrol of large, highly fecund aquatic animals such as carp adds novel risks,” they write in the paper. Furthermore, lab tests can’t truly rule out the possibility of cross-infection, giving it “an enormous evolutionary potential” once released in the wild. In other words, the Australian could breed a super virus which could migrate from species to speciels, potentially posing a global threat to food supply.

Even if it does work, they argue, and even if it doesn’t spread to other species, it’s still a huge risk. Killing the world’s most commonly farmed fish could spread uncontrollably, again — threatening global food security. Also, 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”. So it’s definitely a high risk situation, and it’s a risk we shouldn’t be taking, researchers argue.

“[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 response from Australian officials has been vague at best. The coordinator of the National Carp Control Plan, Matt Barwick, dubbed “The Carpinator” by the agriculture minister, is still an enthusiastic supporter of the project, and he says they’ve already considered the issues addressed by the British scientists. He also said most parts of the world already have the virus, and it’s never migrated to other populations.

The situation is highly complex, and scientists have different views. 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.”

No matter how you look at it, it’s a complex situation, and no solution really seems good at the moment. It’s a clear and strong reminder that ecosystems are fragile, and every imbalance could cause long-lasting issues which are borderline impossible to solve. If anything, Australians should know that by now.