They are also warning those taking undersized crabs in the estuary that they could be photographed and reported.
On January 11, a Facebook page Help Stop Illegal Fishing/Crabbing in Mandurah was set up and now has more than 400 members.
Members are told ‘post your common seen spots and lets stop the fishing and get our marine life back intact.’
Dudley Park resident Val Gallop said she and her husband came from professional fishing families and were dismayed at the decreasing numbers of crabs and fish in the estuary.
‘We are sick and tired of not being able to catch a feed of crabs and want our grandkids to enjoy the activity,’ she said.
‘People are plundering our waters.’
Cushla Westbrook, from Animal Amnesty, said members in groups of five or six would use cameras to catch illegal activity and report it.
Department of Fisheries compliance manager John Breeden said residents were justified in their concerns about illegal fishing for crabs in the estuary.
He said there was an unacceptable high level of non-compliance almost exclusively by fishers wading the shallows and scooping crabs.
‘Too many people are also taking undersize crabs and exceeding bag limits, while many others don’t carry a gauge to measure their catch,’ he said.
‘This has become a 24/7 fishery and officers are witnessing fishing in the very early hours of the morning.’