This little critter and his family are crunching and munching their way through the best of ocean fare; scallops, mussels and oysters.

It's a European Green crab, believed to have arrived in Australia during the 1850's gold rush. During its long stay on the mainland however, it's been a model citizen.

Then about five to ten years ago it finally made it's way to Tasmania, where it's become a menace. It's taken over the habitat of native crabs and has the potential to cause havoc amongst the local fisheries and oyster farms.

"The Green crab has very strong claws and is very well adapted to crushing the shellfish. And our all of our native shellfish species are thin shelled which makes them very susceptible to damage by the green crab."

Apart from its healthy appetite, the crab is incredibly hardy and a rapid breeder, with the female producing up to185 thousand eggs at a time.

Scientists from Australia's science agency CSIRO are trying to find a way to stop them spreading. By studying them under the sea as well as in the laboratory. One simple yet affective way is to trap them, but scientists are also working on ways to change the crabs genetic makeup, to slow down or completely stop their breeding.

"The crab has had a big impact in other countries that it's invaded including both coasts of the United States where it has decimated shellfish populations and drastically affected marine farming operations but also the shell fish fisheries over there."

By working with marine farmers, scientists hope to develop ways to control this potentially multi million dollar threat to the Tasmanian shellfish industry.

Craig Proctor
CSIRO Marine Laboratories
GPO Box 1538
Hobart TAS 7001 Craig.Proctor@csiro.au