Fish death blamed on water quality

The Department of Water says poor water quality is to blame for the mass fish kill event in which thousands of species washed up on the banks of the Murray River recently.

The department initially said about 3000 fish had been killed but that number skyrocketed after recent testing.

The number of dead fish between Pinjarra Road Bridge and the river mouth is now estimated to be more than 30,000.

Department of Water officers took water quality, fish and phytoplankton samples at several sites, which principal scientist Dr Tim Storer said revealed low oxygen levels. “The cause of the event is likely to be poor water quality — specifically low dissolved oxygen levels,” he said.

“Recent rains washed organic matter into the river and disturbed sediment that contains very little oxygen. These two factors resulted in dissolved oxygen falling below levels fish could tolerate.”

On Wednesday, May 24, reports of the fish kill event began flooding in through the Department of Water’s FishWatch hotline.

The event sparked warnings from the Department of Health advising against eating or handling fish found in these circumstances or recreating in waterways during a fish kill or algal bloom event. The Department of Water will monitor the situation through its fortnightly water-quality sampling along the Murray River.

People are urged to continue reporting any fish deaths to FishWatch on 1800 815 507.

The recent event comes only months after flooding across the South West resulted in the deaths of species like black bream, cobbler, blue swimmer crabs and whiting in the Peel-Harvey estuary.