First flood, then heat – Australia: Millions of dead fish clog the river

A massive fish kill near a small community in the Australian outback is currently causing horror. According to the New South Wales government, “millions of fish” have already died in the Darling River near Menindee.

Fisheries Authority spokesman Cameron Lay called it a “horrific scene”. For tens of miles, “as far as the eye can see”, there are only dead fish, Lay told Australian broadcaster ABC. Menindee, with a population of just under 500, is about a twelve-hour drive from Sydney.

“The impact on the environment is unimaginable”
“It’s terrible – just dead fish as far as the eye can see,” said resident Graeme McCrabb. It had never been worse, he said, adding, “The impact on the environment is unimaginable.” After recent flooding in the region, fish stocks in the river had risen sharply. But now there is another huge heat wave, the water levels are dropping quickly and the fish are dying.

According to the government, fish mortality is linked to low oxygen levels in the water (hypoxia) as the floodwaters recede. The current heat wave in the region exacerbates the situation, as warmer water contains less oxygen, but at the same time fish have a higher oxygen requirement at higher temperatures.

It is the third time that the Menindee region has been hit by a massive fish kill. Last time in 2019, the cause was the lack of water in the river due to persistent drought and a toxic algal bloom. Even then, the New South Wales government warned it wouldn’t be the last fish kill.