Darling River system braces for even more fish kills

A run of hot weather combined with low water levels in the Darling has already sparked at least two massive fish kills along a 40-kilometre section of the river system in far western NSW, with an estimated one million rotting fish now clogging the waterway.

Yesterday, Federal Agriculture Minister David Littleproud warned that even more fish kills in the region were possible, and called for an emergency meeting of regional water authorities to discuss how the wide-scale fish kills – this latest one is believed to be the largest in Australia’s recorded history – could be avoided in the future.

The Menindee fish kills are just a few of a number of similar events reported at several sites around the state, NSW Department of Primary Industries senior fisheries manager, Anthony Townsend, said earlier this month. In December, fisheries officers said up to 10,000 fish had died along the same stretch of the river.

Contractors tasked with removing the tonnes of rotting golden perch, bony herring and Murray cod will get to work on the Darling River this week.

“It’s devastating to see the hundreds of thousands of fish killed earlier this week and
we believe this is one of the largest fish kills ever seen,” NSW Regional Water Minister Blair said late last week after visiting the lake system near Menindee.

“We realise the clean-up from this event is significant and we will provide whatever
help we can to the local communities.”

Blair said the region needed “significant rain” to generate replenishment flows “otherwise these impacts will persist and possibly increase throughout summer”.

“You can’t dismiss the impact of drought when in the last six months, we have had 30 gigalitres of water flow in the Northern System, while in an average year we would expect 4000 gigalitres,” he said.

“The numbers speak for themselves. “This is a devastating ecological event and we must address the impacts and recovery with facts and evidence rather than political scaremongering.”

Warmer weather and the Darling’s slow-moving water have created an ideal breeding ground for blue green algae. However, when the water cools or starts moving again, the algae dies, releasing toxins into the water.

The toxins can stay in the water for up to three months.

Prime Minister Scott Morrison said a NSW Labor report released this weekend claiming the Government had ignored warnings about low water levels along the Murray Darling system was wrong, and that drought conditions sweeping the state were the main cause.

"I'm concerned today that some might want to play politics," he told the ABC. "There were reports done by scientists under Labor's contribution to that plan back in 2012, the plan has been operating in accordance with that advice and so we need to just keep on working on the issue."

Environmental groups and locals are laying some of the blame for the fish kills on the Federal Government’s mismanagement of the water system since it took over from the Murray-Darling Basin Authority last year, claiming water from the Menindee lakes water storage system was diverted to irrigators despite the drought conditions sweeping the state.

However, irrigators say they have received no water allocations from the lakes in the last 12 months.

On the bright side, fisheries officers are collecting the ear bones, or otoliths, from Murray cod killed in the algal blooms for further studies.

“Otoliths allow us to work out how old a fish is and can be used to help establish age and length/weight relationships, as well as potentially unearth other secrets including where the fish was born and spent its life through microchemistry work,” the NSW Department of Primary Industries said.

“All of this new knowledge will help improve how we manage waterways and the fishery across the entire Murray-Darling Basin to help protect and improve native fish populations when conditions improve.”