Australian Academy of Science report blames over-extraction before drought for Darling fish death

A report on mass fish deaths in the Darling River has called for better management to allowed better flows but a Federal Minister says that’s impossible unless the scientists know a rain dance.

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Mass fish deaths in the Darling River were caused by a lack of water in system due to drought and water diverted to irrigators, researchers say.

The Australian Academy of Science, at the request of Labor, on Monday released its report into three fish kills near Menindee over summer.

An expert panel found the severity and rapid succession of the kills were “unusual”, and that hot temperatures led to the growth of blue-green algae which depleted the oxygen levels in the water.

Panel chair Prof Craig Moritz said a review found the catastrophe could have been avoided with more water.

“We are all distraught by these fish kills,” Prof Moritz said. “The root cause of the fish kills is that there is not enough water in the Darling system to avoid catastrophic decline of condition through dry periods.

“(They were) partly due to the ongoing drought. However, analysis of rainfall and river flow data over decades points to excess water extraction upstream.”

The panel recommends action to ensure there is sufficient flows, and sustainable management within the next six months.

National emergency: The death of the Darling

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University of Adelaide Centre for Global Food and Resources Professor, Sarah Wheeler, said South Australia, the Coorong and Lower Lakes would benefit from the recommendation to reallocate water in the northern basin.

She said reassessing sustainable diversion limits — which outline how much water, on average, can be used — across the basin, and lifting the cap on buybacks was the most cost effective way to achieve water reallocation, and improve flows to SA.

Researchers do not know how many Murray cod and golden perch fish remain in the river system.

“We already know that the Murray cod is a threatened species,” Prof Wheeler said.

“This fish kill has basically made the situation worse so, in a sense, that has ramifications for SA and Murray cod through the whole system.”

She hopes the Commonwealth fast tracks an assessment of the Murray cod’s threatened status to understand the effects.

Opposition environment spokesman Tony Burke today called for a meeting of basin stakeholders to discuss the recommendations and act to prevent the “environmental catastrophe” from continuing.

He said Labor was committed to separating the compliance function from Murray Darling Basin Authority and make it the responsibility of the Environmental Protection Agency it announced last year — a recommendation from last month’s Productivity Commission report. It will also remove the cap on buybacks.

Water Resources Minister David Littleproud said improving flows in the Darling River was impossible with “a really good rain dance”. Picture Kym Smith

Crossbench senators today reignited calls for a federal Royal Commission into the Murray Darling.

Greens spokeswoman Senator Sarah Hanson-Young said mismanagement was again an issue as too much water was sucked out of the river.

“What this shows is how important a federal royal commission is,” Senator Hanson-Young said.

“Recommendations for a pumping embargo and for water to be bought for the River need to be implemented immediately.”

Mr Burke said Labor would seek to implement the recommendations from Murray Darling reports before considering a royal commission.

Water Resources Minister David Littleproud said the report made some sensible findings and recommendations, and “some not so sensible”.

“Taking ‘urgent steps to ensure there is sufficient flow’ in the Darling is impossible unless these scientists know a really good rain dance,” Mr Littleproud said.

The Murray–Darling Basin Authority said it would consider the new report, along with the findings of an independent panel that will provide an interim report to the Federal Government on Wednesday.