They are voracious predators and could have large impacts on the oyster industry and native marine ecological communities. 

Following our online coverage of the crabs, Grant Seery posted on the Narooma News Facebook page a photo of crab he came across in Wallaga Lake recently wondering if it was one these introduced marine pests.

We were able to send it off to the experts assisting the Aboriginal rangers with their crab control project further north in the Eurobodalla. Click here for out initial story on trapping the crabs

Sophie Hall-Aspland, coordinator of the Mogo Local Aboriginal Land Council sea rangers, sent it off to crab expert researcher Dr Cliff Garside, who identified it as a European green shore crab, so they are definitely present in Wallaga Lake.

Batemans Marine Park acting manager Justin Gilligan said the key distinguishing characteristic was the five spines on either side of the eyes on the carapace.

“The European green shore crab can range in colour from olive to reddish brown, and there are also a wide variety of other crab species that can be green in colour,” he said. “Those five spines are the key distinguishing characteristic to keep an eye out for.”

According to fact sheets put out by NSW Department of Primary Industries, the crabs have been sighted at Burrill Lake, Clyde River/Batemans Bay, Tomaga River, Candlagan Creek, Coila Lake, Lake Mummuga, Wagonga Inlet, Nangudga Lake, Corunna Lake, Tilba Tilba Lake, Merrica River, Wallaga Lake, Bermagui River, Cuttagee Lake, Wapengo Lake, Nelson Lagoon, Merimbula Lake, Pambula Lake, Twofold Bay (including Curalo Lagoon, Shadracks Creek, Nullica River, Towamba River/Kiah Inlet, Fisheries Creek), Wonboyn Lake and Nadgee Lake.The European green shore crab can live in a variety of habitats but is generally found close to the shore on mudflats or amongst rocks in protected bays and estuaries. Click here for more

The Narooma News is also aware that several years ago university researchers were actively trapping the crabs in Corunna Lake.

According to the Sapphire Coast Marine Discovery Centre, researchers from Macquarie University, in partnership with the discovery centre, the Southern Rivers Catchment Management Authority, Batemans Marine Park and the Department of Primary Industries, have also secured funding from the Australian Research Council Linkage Grants program to investigate biological and physical factors that limit the spread of the crabs.

To date, a quarterly trapping program in 14 South Coast estuaries has failed to turn up EGSC in estuaries that spend most of their time closed to the ocean. This suggests that prolonged periods of sandbar closure hinder the crabs invasion of south coast estuaries.