Genetic manipulation to free Murray-Darling of carp

CSIRO scientists have hatched an ambitious plan to wipe out carp in the Murray-Darling River, by using genetically manipulated carp that lack the ability to change sex.

After spending $4 million over the last four years to get proof-of-concept, CSIRO has received $2.9 million for the next three years of research from the Murray-Darling Basin Commission (MDBC).

CSIRO estimates that the project will take around seven years before the carp are ready to release into the wild population.

Kevin Goss, General Manager for Natural Resources at MDBC, said that the commission acknowledged the timeline for the project and will be working closely with CSIRO.

"It will be a fairly active partnership over the next seven years," he said.

Carp change from male to female during development. By introducing "daughterless" carp whose offspring can no longer change from male to female, more male carp are produced every generation and, in theory, the numbers of carp should decrease.

"It should be a perfectly safe method of control," said Dr Ron Thresher, who leads the program at CSIRO Marine Research.

He explained that the gene is specific to carp and would not be able to transfer to other species. In any case, he said, carp don't hybridise with native fish species.

"The advice to us from CSIRO is that this is not GMO technology," said Goss.

There is no transfer of foreign genes to the fish, just manipulation of the carp's own genes, he said.

According to Thresher, the method has been extensively tested in the laboratory on zebrafish and studies are now beginning on mosquito fish.

"Our models tell us how long it should take, but we want to see how long it really takes," explained Thresher.

Goss said that they expected that it would take 20-30 years to significantly reduce carp numbers in the wild. Currently, carp account for up to 90 per cent of the total fish population in some parts of the Murray-Darling River system and native fish have dropped to about 10 per cent of the pre-settlement population.

Goss also emphasised the commission's commitment to community consultation before release of any daughterless carp into the river system.

"We want to be very careful about community reaction," he said. "We have got to make sure that the community is aware of the benefits."

He noted that reduction of carp numbers was just one part of an overall strategy to increase the numbers of native fish in the Murray-Darling River system.