Millions of native fish wash up dead near Menindee in outback NSW

Millions of native fish have washed up dead near Menindee in outback NSW, in a series of mass kills caused by floods and hot weather.

Fish including bony herring, Murray cod and perch have died on the lower Darling-Baaka River, in the state’s far west, along with carp, the state’s Department of Primary Industries said.

Millions of fish have died in a massive fish kill near Menindee in outback NSW. Credit: Graeme McCrabb

“This event is ongoing as a heatwave across western NSW continues to put further stress on a system that has experienced extreme conditions from wide-scale flooding,” the department said on Friday.

The deaths were most likely caused by low oxygen levels as floods recede, a situation made worse by fish needing more oxygen because of the warmer weather.

Bony herring were a boom-and-bust species, the department said, which thrive in floods but are more susceptible to stresses when water flows return to normal.

“NSW DPI understands that fish death events are distressing to the local community, particularly on the lower Darling-Baaka.”

Nature photographer Geoff Looney found huge clusters of dead fish near the main weir at Menindee on Thursday evening.

“The stink was terrible. I nearly had to put a mask on,” he said.

“I was worried about my own health. That water right in the top comes down to our pumping station for the town.

“People north of Menindee say there’s cod and perch floating down the river everywhere.”

Federal Environment Minister Tanya Plibersek said, “Devastated to see the images coming out of Menindee today. It’s tragic to see mass death of fish, known as fish kills, at this scale for the second time in four years.

“I understand the fish kills have been caused by flooding combined with high temperatures which has created low oxygen black water.

“We need to better understand the causes of these kills to better prevent them. That’s why we are investing in the best, updated science.

“It’s also another reason why it’s so important to deliver the Murray-Darling Basin Plan in full. Delivering the plan will help support and rebuild our precious native fish populations.

“We know that climate change is exacerbating extreme weather. Delivering the Plan will support our rivers through the worst of our floods and droughts.”

Mass kills have been reported on the Darling-Baaka River in recent weeks.

Tens of thousands of fish were found at the same spot in late February, while there have been several reports of dead fish downstream towards Pooncarie, near the borders of South Australia and Victoria, since February 20.

Enormous fish kills occurred on the river at Menindee during severe drought conditions in late 2018 and early 2019, with locals estimating millions of deaths.

The department’s investigation involving scientists and Murray-Darling Basin experts found those events were also caused by a lack of dissolved oxygen, amid very low or non-existent water flows, high temperatures and blue-green algal blooms.

Looney said there should be an inquiry into water management and fish deaths.

“It’s getting ridiculous,” he said.

Several state and federal departments are responding to the latest mass kill.

AAP

A guide to the environment, what’s happening to it, what’s being done about it and what it means for the future. Sign up to our fortnightly Clear Air newsletter here.