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Government of Western Australia - Department of Fisheries
Tuesday 21 February 2023

Alexandrium update

Have you seen the algal bloom warning signs around the Swan and Canning rivers? The signs are there to alert river fishers of the potential for the toxic algae Alexandrium, which produces Paralytic Shellfish Toxins (PSTs) that can accumulate in crustacea and bivalve molluscs (mussels).

We are currently monitoring a visible pale orange Alexandrium bloom which was sighted in the Swan Canning Estuary, near Riverside Drive in the city in mid-February.

An Incident Management Team has been convened to manage our response and analysis of samples collected by the Department of Biodiversity, Conservation and Attractions (DBCA) indicates that fishers should adhere to our advice concerning mussels and crabs.

Fishers are advised not to eat mussels or other bivalves caught in the river system and if you see an algae bloom, do not fish in the area. Eating affected crabs and mussels may be dangerous, and in extreme cases, fatal.

To ensure your blue swimmers are Alexandrium-free, remove the head, guts (mustard) and gills before freezing, cooking or eating them. Cooking whole crabs does not destroy the PSTs and could potentially spread the toxin from crab guts into the flesh or broth. Freezing whole crabs could result in PSTs spreading to the flesh during thawing.

And remember - you still have to land and transport blue swimmers home as whole crabs, unless you plan to eat them immediately.

Information on how to clean blue swimmer crabs is available from: Biosecuri​ty alerts or​u/algal-bloom

Last modified: 21/02/2023 9:24 AM

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