Shocking photos shared with Yahoo News show millions of dead fish choking an iconic NSW river system.
The mass fish kill has prompted an investigation by state authorities who have travelled to Menindee, in the state’s far west. The NSW department of primary industries (DPI) said depleted oxygen levels in the water remain a concern, and multiple federal and state agencies are understood to be coordinating a response.
While the region has been home to several mass fish kills, Western Sydney University water scientist Dr Ian Wright said images of the event are some of the “most distressing” he has seen. “It’s so incredibly confronting, I’ve never seen anything like it.”
Some of the images he's responding to show dead fish as far as the eye can see, while others highlight waterbirds lined up in front of the town’s main weir where many of the fish lay dead.
Local man furious after millions of fish die
Many of the most startling images were taken by Menindee resident Graeme McCrabb who said the situation is starting to be "on the nose" as the fish start to rot.
"It's just a carpet of fish for probably 15 to 20 kilometres, it's just unbelievable. There are millions of (bony herring), there are gold and silver perch and a few cod," he said.
Mr McCrabb said he is frustrated by ongoing issues with water quality and he blames state and local management for the issue. "We keep getting fish kills, we keep making the same mistakes," he said.
What are so many fish dead in the Darling River?
It’s believed the deaths were triggered after high levels of organic material entered the water, depleting oxygen and triggering a blackwater water event.
The situation was likely caused by this summer’s extraordinary heatwave coupled with incredible growth of blue-green algae in rivers, Dr Wright suggests. “I have never seen the state so covered in algae,” he said, pointing to a NSW government map that highlights widespread blooms across the state.
“Our rivers reflect our catchment and land use, but it’s also that the floods mobilised so much waste. Nutrient levels are up, and now the rivers have slowed down a lot of the silt has dropped.”
Human activity has also accelerated the problem, he believes. “A lot of rivers are used for the disposing of sewage,” he said. “You get run off from farms. There’s a lot of livestock so there’s a lot of poop and eroded soil.”
Worse fish deaths could be yet to come
Last month hundreds of yabbies were filmed fleeing the Darling River, which feeds into the Menindee Lakes, a sign of worse to come.
Dr Wright suspects this week’s fish kill may not be the worst of it, predicting the problem could spread, causing a “chain reaction of fish deaths” and that the wider food chain could also be affected.
'The smell is going to be unbelievably bad'
“It’s going to be massive,” he said. “What really scares me is all those fish are going to break down. In this temperature, in a wet environment, the smell is going to be unbelievably bad.”
DPI said in a statement it "understands that fish death events are distressing to the local community".
It is urging the community to report fish deaths or observations to the Fishers Watch phone line on 1800 043 536.
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