Roundup: Australia reduces rabbit population by 40 percent with calicivirus, now sets sights on carp

Since their introduction to Australia, aboard the first fleet of ships which settled in 1788, rabbits have plagued plants and animals and been a menace to the country's agriculture.

It's been estimated by Australia's Department of Primary Industries that rabbits cost over 200 million Australian dollars (148.26 million U.S. dollars) per year to farmers and threaten more than 300 Aussie species.

In an attempt to deal with the cute but problematic creatures, the most extensive invasive species reduction strategy in the nation's history was undertaken in March 2017 and has already lowered the population by 40 percent, according to the New South Wales State Coordinator of project, Quentin Hart.

"My main role was to work with our regional management organizations, known as Local Land Services, to help coordinate the release of the virus on approximately 200 farms and properties," Hart explained to Xinhua on Tuesday.

"That was part of a national program which included about 600 sites in Australia, which was coordinated by the Invasive Animals Cooperative Research Centre with support from the Department of Primary Industries, so that means there were hundreds of farmers and conservation land managers that were involved in distributing the virus."

In order to estimate the reduction in rabbit numbers, spotlight checks have been conducted whereby participants travel along a measured line.

This process was undertaken nationwide before and after the release of the virus, and has already revealed a substantial drop, leading into the cooler and wetter months before winter when the virus is thought to be at its most effective.

But this is not the first time Australia has attempted to tackle the wrath of the floppy-eared troublemakers.

The first major organized strategy was Western Australia's rabbit-proof fence in 1907, an effort which saw a 3,256 km barrier erected across the country.

Unfortunately, the structure had little success containing the pests to the eastern half of the nation, so during the 1950s, the first viral strategy was implemented.

"It was certainly a lot worse in the past," Hart said.

"Myxoma virus knocked the population down significantly, but over the years they have recovered again and have developed some resistance to the virus."

In the mid 1990s, a new attempt was made with the first strain of the calicivirus in Australia, known as the Czech strain.

"That had a dramatic effect on reducing rabbit populations," Hart said.

"But once again the rabbits subsequently developed some resistance to that strain as well."

This year, the third, most targeted approach began with another calicivirus strain from South Korea, called K5.

"The virus comes in a freeze dried form, its then made up into a solution, the solution is then applied carrot or other bait and that bait is distributed to where the rabbits are," Hart said.

"It's important to point out, this particular strain of calicivirus is completely specific to rabbits."

"It won't even affect Hare's and there is no risk to any other animals either getting it from the bait or getting the virus from eating rabbits."

But Australia's foreign pest problems aren't just limited to bunnies or land, the Department of Primary Industries now have their sights set on eradicating carp from the country's waterways as well, following the success of the calicivirus.

"What is being proposed is what's known as a koi herpes virus with intention to reduce the population of carp to allow the recovery of native fish populations."

"In some of Australia's waterways that have huge numbers of carp in them, estimates say 80-90 percent of those waterway's fishlife or biomass is actually carp."

"In Australia the formal release of these viruses is subject to very stringent federal and state government review of the data to make sure they are safe, they are target specific and are likely to be effective," Hart said.

As manager of invasive species strategy and planning at the state Department of Primary Industries, Hart said the move could have great benefit to native marine life and local fisherman, however, the proposal for the plan is not without its challenges.

"One issue which has been well publicized is the rate in which it might kill carp and what that might mean in terms of having so many dead fish in the rivers," Hart said. Enditem