Rabbit numbers have nearly halved on the Eyre Peninsula after a new strain of the calicivirus was released in February.
The Korean RHD1K5 strain of the calicivirus virus was released in six spots on the Eyre Peninsula: Coffin Bay National Park, Lincoln National Park, Port Neil, Lipson and two areas near Elliston.
Primary Industries and Regions South Australia biosecurity officer Greg Mutze said all recorded sites across the state had a 20 to 80 per cent decrease in rabbits within the first month.
The virus had undergone five years of testing prior to being released in 500 locations around Australia, including 50 in South Australia, to make sure the virus was not transferable to other species including native wildlife.
“Numbers of the rabbits were increasing since 2004, which prompted us to look at more virulent strains,” Mr Mutze said.
“The virus was particularly successful in the Lincoln National Park, killing 80 per cent of the rabbit population.”
When we release a virus, the numbers are severely suppressed and then have a partial recovery.PIRSA biosecurity officer Greg Mutze
He said an outbreak of the untested and untried virus, the RHDV2 calicivirus, was thought to be responsible for some rabbit deaths near Elliston.
“The virus originally emerged in France and there was spot outbreaks in West Africa, Canada, and Canberra.
“It was discovered in Australia in 2015 and soon spread to cover many parts of southern Australia.
“There’s been the same average change across the regions introduced with the RHDV1K5, which is just under 50 per cent,” Mr Mutze said.
The virus spread about 12 months before the tested RHDV1K5 virus was spread and killed most of the rabbits in Elliston.
The untested virus only kills European rabbits and a few species of hares.
However Mr Mutze warned people not to be complacent.
“When we release a virus, the numbers are severely suppressed and then have a partial recovery.
“Bio controls are very good in suppressing rabbit numbers but to really control the population we have to get other control measures out, such as baiting programs, warren ripping and fumigation,” Mr Mutze said.
There are vaccinations available for pet rabbits but they are only partially effective for the untested RHDV2 virus.