The state’s river authority said it was a result of an ongoing heatwave affecting the Darling-Baaka river.

Locals say it is the largest fish death event to hit the town, that experienced another significant mass death of fish just three years ago.

In a Facebook post, the NSW Department of Primary Industries (DPI) said the heatwave put “further stress on a system that has experienced extreme conditions from wide-scale flooding”.

Heatwaves have become more frequent, more intense, and last longer because of human-induced climate change. The world has already warmed by about 1.1C since the industrial era began and temperatures will keep rising unless governments around the world make steep cuts to emissions.

(BBC News)

Half of the pod, thought to be pilot whales, are believed to be still alive. Rescuers are being sent to the area.

It’s unclear what caused the whales to beach on a sandflat at the entrance to Macquarie Harbour, the same remote location where Australia’s worst stranding occurred two years ago.

It comes a day after a separate mass stranding in northern Tasmania.

The incident on Tuesday saw 14 young sperm whales found dead on King Island, in the Bass Strait.

Experts were planning a rescue of the 230 whales discovered on Wednesday but the operation would be “complex” due to the location, Tasmania’s Department of Natural Resources and Environment said in a statement.

“It appears about half of the animals are alive.”

Macquarie Harbour is a large, shallow inlet in a rural area. More of the whales are expected to die overnight.

Locals have been covering the stranded whales with blankets and pouring buckets of water over them to try to keep them alive.

(BBC News)