Fish experts have said the mass die-off of fish in the Darling River could result in lower native fish stocks in South Australia, Queensland and Victoria.
Up to a million Murray cod have died across a 40-kilometre stretch of river at Menindee, near Broken Hill, with the New South Wales State Government confirming another fish kill has occurred at Lake Hume.
Previous research has found much of the Murray Darling Basin’s native fish population comes from the Menindee Lakes and the lower Darling River.
Some of the fish killed off in the mass fish death are already endangered species of Murray cod and silver perch.
RecFish SA executive director, Danny Simpson, said the Lakes are the “engine room” for fish breeding, particularly the golden perch.
“Fish die-offs such as this, which are extremely large, have the potential to really have a detrimental impact on recreational fishing in this state,” Mr Simpson said.
“The water management practices of some upstream areas really need to change immediately so that we don’t have these die-offs occurring in the future.”
Freshwater fish ecologist Lee Baumgartner said it would take a number of years before the impacts on other states could be estimated.
“In certain years the Darling has a really big influence … but not every year,” Dr Baumgartner said.
“If this year was a really strong year, where fish were going to breed in the Darling, it could have a really big impact.
“In 2012 there was a really big fish kill event which had a big impact for a few years but the fish recovered fairly quickly, within five years we saw fish communities coming back.”
Water policy reform suggested
The Federal Department of Environment and Energy said the crippling drought conditions in the area had affected water temperatures in the river and sparked the algal bloom.
Numerous experts have called the fish deaths a preventable catastrophe.
Australian National University professor, John Williams, co-authored a paper on the health of the Murray-Darling Basin.
He said too much water is being removed from the northern Basin and irrigators need to reduce their take by 40 per cent.
“Any water management policy must be able to deal with the conditions we currently have, and clearly the policy is not doing that,” Professor Williams said.
“The Murray Darling Basin Plan (MDBP) has not removed water back to the environment in sufficient amounts to actually keep the river flowing so we avoid these conditions.”
Federal Minister for Agriculture and Water Resources, David Littleproud, proposed using $5 million for a native fish recovery strategy and will seek agreement for the money to come from Murray-Darling Basin funds.
Professor Williams said fish deaths will continue to occur until flow regime is corrected.
“We’ve got some very difficult times ahead. We need to stop what we’re doing and audit what’s going on in this water reform process,” he said.
The NSW Irrigator Council chief executive, Luke Simpkins, said a 40 per cent reduction in water uptake for NSW irrigators would “destroy” the cotton industry.
“Already our people have suffered greatly as a result of the drought,” he said.
“A lot of people have a go at cotton but the reality is people are working within their license conditions given to the farmers by Water NSW.”
Mr Simpkins also took a stab at the MDBP before he hopefully pleaded for rain.
“On the environmental side people are saying the plan isn’t working … and where farmers are using irrigation people are saying it’s not working either,” he said.