Recreational crab fishers have been reminder to be on lookout for the noxious Asian Paddle Crab.
This pest species, Charybdis japonica, has been found in the Swan in recent years and there was another confirmed capture recently in Matilda Bay, making number 4.
An alert fisher, who caught the crab in a drop net on the Swan River late last month, helpfully reported his find through FishWatch.
Recreational fishers are playing a key role in helping control the Asian Paddle Crab.
All four Asian Paddle Crabs found in the Swan River in 2012 were all caught by recreational fishers. Crab fishers are asked to continue their vigilance to help prevent the pest species from establishing itself in Western Australia.
Its definitive features are the sharp spines between the eyes and the six spines down each side. Fishers should first look at any crabs that look different to blue swimmers and then check for the spines between the eyes.
If the Asian Paddle Crab becomes established in Western Australia, as it could out-compete native species like the blue swimmer, spread diseases to other crabs and prawns and would probably be impossible to eradicate.
Crab fishers should check their catches and, if in doubt take photographs, retain suspect crabs, note the fishing location and contact authorities.