Ecologist confident Murray cod can recover after years of ‘insults and injuries’ as fish kill threatens Darling-Baaka River

A river ecologist is confident one of Australia’s most loved native fish can recover and prosper despite fears of another mass fish kill.

The majestic Murray cod have swum the Murray River for thousands of years but their numbers have declined due to factors like significant fish kills, historical overfishing and water management contributing to their decline.

Charles Sturt University Associate Professor Paul Humphries has been researching the fish for nearly 20 years and expects they can bounce back. 

“Both the rivers and the fish have been subject to all sorts of insults and injuries over the years,” he said. 

“I’m fairly positive with all the work, the biology, science and good management, I am confident they will swim into the future in ever increasing numbers.”

Dr Humphries said native fish in the Murray River were resilient creatures but needed support.

“Murray cod will bounce back if we let them,” he said. 

“Which means allow[ing] them to have passage up and down the river, which allows them to have the types of habitats they need, and not to put too much pressure on them when they’re trying to recover,” Dr Humphries said.

“That’s why it’s really important that we have some sort of fishing regulations that allow them to recover from any adverse events that might happen to them.” 

Fish kill concerns

In the New South Wales town of Menindee, some locals are concerned they could see another mass fish kill and loss of native species, such as earlier this year when millions of fish died. 

Menindee resident Graeme McCrabb said he had seen about a dozen large dead cod in the Darling-Baaka River, which he feared was a sign of a future fish kill. 

“The potential for another major fish kill sits squarely in the frame at the moment,” he said. 

“The river here looks pretty ugly at the moment.

“To look at the water and see the [poor] quality, and some of the algal blooms that are forming now in really cold temperatures, is very concerning for the [warmer] months ahead.” 

Healthier downstream after floods

For Ngarrindjeri man Shane Karpany, who lives in South Australia’s Riverland, the Murray cod is an especially significant creature.

While Mr Karpany has seen a decline in numbers, he also believes the species can recover, particularly after the recent summer floods. 

“[The flood] cleaned out the river and got rid of a lot of stuff that was backing it up,” he said.

“It’s opened up all of these creeks and waterways where the Murray cod can lay its eggs and bring more baby cods into the waterways.  

“At the moment, [I’m hearing] how healthy our river area is. Into the South Australian border and down to Lake Alexandrina, our water seems to be pretty good. 

“But obviously we get that flow-on effect that comes from Victoria and New South Wales too.” 

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