DON’T eat fish, crabs or other shellfish collected from the Swan River between the old Swan Road Brewery and Garratt Road Bridge.
An algal bloom is plaguing the river and the Department of Health says recent testing has confirmed high levels of potentially toxic microscopic algae, which can produce “paralytic shellfish poisoning”.
Cooking won’t kill the toxins and symptoms include tingling and numb lips, prickly fingers and toes, nausea, vomiting, impaired balance, dizziness, slurred speech, double vision, weakness, difficulty in swallowing or breathing, and diarrhoea. In severe cases it causes muscular paralysis.
Potentially affected shellfish include oysters, mussels, clams, pipis, scallops, cockles and razor clams.
The health department’s Michael Lindsay says farmed shellfish are okay as commercial operators have strict quality assurance testing, and “other recreational activities including swimming, skiing and boating are not likely to be affected by this micro-algae species, but as a general rule swimming should be avoided in areas of discoloured water”.
The department is putting up health warning signs at key fishing spots along the river.
It’s not known how long the bloom will linger. The department puts the current bloom down to the right mix of temperature, salinity, calm water, low rainfall and too many nutrients.