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Government of Western Australia - Department of Fisheries
Friday 18 December 2020

Clean and prepare recreational blue swimmer crab catches from the Swan and Canning rivers

​With the opening of the blue swimmer crab fishing season throughout the Swan and Canning rivers this month, it’s timely to remind recreational fishers to remove the head, guts (mustard) and gills from crabs caught in these rivers before freezing, cooking or eating them.  

We remind fishers they still have to land and transport their blue swimmers home as whole crabs, unless they plan to eat them immediately.

This caution is due to the detection of the toxic alga Alexandrium in the Swan River in the past few days. This organism can produce Paralytic Shellfish Toxins (PSTs). PST has been present in the Swan and Canning rivers, during the last two crab seasons.  

The PSTs accumulate in crustacea and mussels. Eating affected crabs and mussels may be dangerous and, in extreme cases, fatal. If you become ill after consuming crabs or mussels seek medical attention promptly.

Cooking or freezing whole crabs does not destroy these PSTs. Cooking crabs with their heads, guts (mustard) and gills attached could potentially spread the toxin from crab guts into the flesh or broth.  Freezing crabs (with guts still in place) could result in PSTs spreading to the flesh during thawing. Comprehensive instructions, on how to clean blue swimmer crabs properly, are available in a new flyer and a video to assist recreational fishers.

There are also new caution signs installed at popular jetties, boat ramps and fishing locations that form part of a comprehensive and ongoing Alexandrium education campaign formulated by the Department of Primary Industries and Regional Development (DPIRD) and the Department of Biodiversity, Conservation and Attractions (DBCA).

On the rivers, DPIRD will be collecting blue swimmer crabs for testing during the season and DBCA will monitor water quality in the Swan Canning estuary every week. These actions will inform the Alexandrium management response in the coming months. 

At this stage recreational fishing will remain open for blue swimmer crabs (December 1 to August 31 inclusive) in the Swan and Canning rivers. However, we remind river-users to pay attention to signs and watch out for Alexandrium updates in the media and outdoor/fishing tackle stores.
The Department of Health maintains a general warning not to eat shellfish including mussels, oysters, clams, pipis, scallops, cockles and razor clams from the Swan and Canning rivers, at any times. Urban waterways can contain heavy metals, microbial and other contaminants that may affect the quality of these types of seafood. Commercially bought WA shellfish undergo testing via quality assurance processes to allow consumer confidence that it is safe to eat.

Further information including an Alexandrium video, flyer, crabbing rules and frequently asked questions is available online: and

Last modified: 18/12/2020 10:10 AM

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