Update: Algal bloom warning in Swan and Canning Rivers

24 January 2020

The Department of Health has identified a toxic algal bloom in the Swan and Canning Rivers and warns people not to eat fish, crabs or shellfish collected from either of these rivers.

Water with algal bloom

This reminder comes ahead of the Australia Day long weekend, a peak period for recreational use of these waterways.

Shellfish includes oysters, mussels, clams, pipis, scallops, cockles and razor clams.

The toxins produced by this microscopic species of algae can produce a type of poisoning known as paralytic shellfish poisoning (PSP). Cooking will not destroy these toxins.

In severe cases PSP may cause muscular paralysis in people who consume affected shellfish, crabs or fish.

People who consume wild shellfish, crabs or fish collected from the affected area of the Swan and Canning Rivers may experience symptoms including:

  • tingling or numbness of the lips
  • prickliness of the fingertips and toes
  • nausea or vomiting
  • impaired balance
  • dizziness
  • slurred speech
  • double vision
  • weakness
  • difficulty in swallowing or breathing
  • loss of fluids and diarrhoea.

Anyone who has consumed shellfish, crabs or fish collected from the affected area of the Swan River and experiences any of these symptoms should seek urgent medical attention, particularly if they have difficulty breathing.

They should also retain uneaten portions of mussels or other shellfish to help determine a likely cause of any symptoms.

Farmed shellfish purchased in supermarkets and other commercial outlets in WA are not affected.

Other recreational activities including swimming, skiing and boating in the Swan River are not affected by this microalgae species, but as a general rule swimming should be avoided in areas of discoloured water.

DBCA will continue to monitor algae levels within the Swan and Canning Rivers and will resample mussels and crabs for toxins within the next two weeks.

A map detailing affected waterways can be viewed on the DBCA website.