Alert issued for fish deaths

24 Dec 2021

The NSW Department of Primary Industries (DPI) has warned residents along the Barwon-Darling-Baaka Rivers to be alert for fish deaths in the coming days and weeks due to hypoxic blackwater, caused by decaying sticks, leaves and other organic matter being washed into the river.

DPI’s Director Freshwater Environment, Cameron Lay said significant rainfall across most of the Northern Basin has resulted in extensive inundation of floodplain areas, with flows into the Barwon Darling system causing poor water quality, including low dissolved oxygen levels.

“When there is a lot of organic material washed into the river, its rapid decay takes dissolved oxygen from the water,” Mr Lay said.

“If dissolved oxygen drops to very low levels, this can cause ‘hypoxic’ water which can be stressful for native fish and can lead to fish deaths.

“In addition, water temperatures in the rivers are increasing due to the hot weather, which means organic material dissolves more rapidly than in cooler temperatures, increasing the likelihood of low dissolved oxygen.”

Other areas of concern for potential fish deaths are in the mid Murrumbidgee, including the Edward Wakool rivers near Deniliquin and Yanco Creek system.

‘While these areas are of particular concern to DPI Fisheries, we’re asking everyone to be on the lookout for fish deaths, given the widespread rainfall and flood activity across the State in recent months,” Mr Lay said.

“Summer flooding across coastal catchments also presents high risks of significant fish deaths due to large scale blackwater events.”

“DPI Fisheries will continue to work with partner agencies, who are responsible for managing and monitoring water quality and conditions.

Community members are encouraged to report any fish deaths or observations through the Fishers Watch hotline on 1800 043 536.

For more information on fish deaths, visit the NSW DPI website.

Media contact: 02 6391 3686