Mass starfish deaths in Perth not linked

The death of hundreds of starfish on Perth beaches is not due to any single cause and might be a natural occurrence, the Department of Fisheries says.

Earlier this month almost 200 dead starfish were found at a Perth beach, after an initial report indicated there could be up to 1000.

The department said while further testing and analysis will be undertaken, previous starfish deaths have been attributed to their life cycle.

The dead starfish have been found at South Beach, North Coogee, North Fremantle and Dalkeith.

Meanwhile, the Department of Health has warned people not to eat shellfish from the lower part of the Swan and Canning Rivers, due to potentially harmful microscopic algae.

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

It does not include crustaceans such as shrimp, prawns, crabs or lobsters.