Fourth Asian crab found
three, six and 12 months later, which caught no Asian paddle crabs, 1139 native blue swimmers, 273 fourlobed swimmers and one example each of a three-spot and coral crab.
Ms Massam said larvae in a ship’s ballast, individual crabs inside hulls or larvae drifting from the north on the Leeuwin Current were the most likely sources of Asian paddle crabs, but it was almost impossible to identify the culprit from the hundreds of vessels visiting or moving around WA each year.
The specimens from Matilda and Mosman bays were all male adults and Ms Massam said it was a “good sign” that no immature individuals, indicating breeding, had been found.
Finding a female would change Fisheries’ response to the threat, which she said was currently suspected to be “isolated males dropping off a boat”.
Since 2013, Fisheries has received about 400 calls from crabbers with suspect crabs but many were the native four-lobed swimming crab that has no spines between its eyes, while the Asian paddle crab has sharp spines between the eyes and six spines down each side
The Matilda Bay fisherman had a Fisheries alert about the Asian paddle crab in his backpack and took the specimen to scientists that day, after calling the biosecurity Fishwatch on 1800 815 507.
A free marine pest mobile telephone phone application is at www.fish.wa.gov.au/ biosecurity.
Department of Fisheries marine biosecurity officer Marion Massam with the Asian paddle crab caught near Matilda Bay, Crawley.
The poisonous Asian paddle crab.
The native four-lobed swimming crab.