The Swan River has come under investigation after at least 600 dead fish were reported floating in its waters by The Parks and Wildlife Service.
The reports came from Garratt Road Bridge in Bayswater and upstream in northeast Perth, but the extent could be even further with investigations still underway.
Department of Food and Agriculture WA fish pathologist Paul Hillier says the discovery of the mass of dead fish is likely due to intense rainfall over four days and could potentially cause further complications in the already changing environment of the Swan and Canning rivers.
“The longer-term impacts of the flood flow will likely see increased algal activity, possibly including blue green algal blooms, deoxygenation and further fish deaths,” he said.
Hillier anticipates flow-on effects into the Swan River including increased bacterial water quality and a large number of debris expected to float downstream in the coming weeks.
“This will not only affect the Swan, it will have a knock-on effect to other water bodies and natural areas in the surrounds which could lead to a larger environmental crisis if we are not careful,” he said.
The Department of Health have warned the public against collecting the fish and to avoid swimming and fishing in areas of the Swan River where investigations are taking place.
Communication and education are now underway aimed at individuals collecting marine life, particularly surrounding avoiding mussels and removing the head and innards from blue swimmer crabs before freezing or consuming.
An internal Department of Biodiversity, Conservation and Attractions incident management team has been formed to monitor this event and its impacts and samples of the marine life found are expected to be sent in for further testing.