CRAB fishers have reported 12 suspicious crabs from locations including South Guildford, East Fremantle, Kwinana and Falcon Bay, since the latest warming about the threat of the pest Asian paddle crab last month.
‘The species reported, which were all natives, included red bait crab, common sand crab, four-lobed swimming crab and red-spotted box crab,” Department of Fisheries senior management officer Marion Massam said.
Ms Massam said crabbers on jetties and shores had a role equally important to those in boats in keeping watch for suspicious crabs.
The Asian paddle crab has sharp spines on the front of its shell between the eyes, while the small, brown native four-lobed swimming crab, with which it has often been mistaken, has no spines between the eyes.
The pest was discovered after four specimens were caught in Mosman Bay in 2012 and 2014, and one in Mandurah in 2010, but there have been no subsequent reports.
However, the Department of Fisheries remains on guard against the invader because the aggressive species has spread in Auckland estuaries and 100km north to Whangarei in New Zealand since 2000.
Ms Massam said WA researchers were doing active surveillance four times in the Swan River each year, and an annual week of intensive monitoring, including water sampling, crab traps and dive transects for invasive species.
“It is likely that if no paddle crabs are found in the next year or two, the risk of paddle crabs still being present in the Swan River would be considered to be low,” she said.
Suspicious crabs should be photographed, their catch location noted and the specimen preserved for analysis.
A pest alert is at www.fish.wa.gov.au and FishWatch can be contacted on 1800 815 507.