Health authorities have warned people not to eat fish, crabs or shellfish collected from the Swan River, after tests revealed high levels of potentially toxic microscopic algae.
The WA Health Department said the warning applied to the area extending from the Old Swan Brewery, Mounts Bay Road, and upstream to the Garrett Road Bridge, including the areas of Perth Waters, Elizabeth Quay, Barrack Street Jetty and Claisebrook Cove.
Acting Environmental Health executive director Dr Michael Lindsay said that ingestion of toxins produced by the detected microscopic algae could produce a type of poisoning known as paralytic shellfish poisoning.
"These algae, which are not visible to the naked eye, can produce a toxin which could be absorbed by filter feeding shellfish and potentially consumed by crabs and finfish to a lesser extent,” he said.
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READ NOW“It is important to note that cooking will not destroy these toxins.”
People who consumed wild shellfish, crabs or fish collected from the affected area could 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.
In severe cases PSP can cause muscular paralysis.
Dr Lindsay said that anyone who had consumed shellfish, crabs or fish collected from the Swan River and experienced any of the symptoms should seek urgent medical attention, particularly if they felt respiratory distress.
Shellfish includes oysters, mussels, clams, pipis, scallops, cockles and razor clams.
As a general rule people should avoid eating wild shellfish collected recreationally as the safety could not be guaranteed. This was particularly the case for rivers, estuaries or other waterways where there was an increased likelihood of contaminant or nutrient inputs that in turn can lead to increased microscopic algae growth.
Dr Lindsay said farmed shellfish purchased in supermarkets and other commercial outlets in WA were not affected because there was a strict quality-assurance program to ensure they were safe for human consumption.
Other recreational activities including swimming, skiing and boating were not likely to be affected by the microalgae species, but as a general rule swimming should be avoided in areas of discoloured water.