Warning area expands for toxic Swan River algae

A WARNING issued for people not to eat fish, crabs or shellfish caught from the Swan River has been expanded.

Recent testing found elevated levels of potentially toxic microscopic algae and led to the department warning about catches made between the Old Swan Brewery and the Garrett Road Bridge.

The originally affected area included commonly used areas of Perth waters such as Elizabeth Quay, Barrack Street Jetty and Claisebrook Cove, but now reaches from Pelican Point to West.

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Acting Environmental Health executive director Michael Lindsay said ingesting toxins produced by the detected microscopic algae ‘Alexandrium spp.’ 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.

“It is important to note that cooking will not destroy these toxins.”

‘Don’t eat the fish’: Warning over Swan River algae

People who consume wild shellfish, crabs or fish collected from this affected Swan River area 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.

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

Dr Lindsay said that anyone who had consumed shellfish, crabs or fish collected from the Swan River and experiences any of these symptoms should seek urgent medical attention, particularly if they feel any respiratory distress.

“Do not discard uneaten portions of mussels or other shellfish as these may assist with determining a likely cause of any symptoms.”

Swan River safe for swimmers

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

As a general rule people should avoid eating wild shellfish collected recreationally as their safety cannot be guaranteed.

This is particularly the case for rivers, estuaries or other waterways where there is 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 are not affected as there is a strict quality-assurance program to ensure they are safe for human consumption.

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

While the alga has occurred in the river in the past, the cause of the current situation is thought to be suitable temperature and salinity, available nutrients, calm water conditions and low rainfall.

It is not known how long the bloom will persist, but the Department of Biodiversity, Conservation and Attractions is expected to continue to monitor algae levels within the Swan River and provide advice to the Department of Health.

Warning signs have been placed along the river.