Cold summer flows wiping out a third of young native fish

Young native fish are dying in the wake of cold irrigation water flowing down the Goulburn River this summer.

Cold cull: Young fish such as these albino and normal Murray cod are being wiped out by the flush of cold water down the Goulburn River each summer. Picture: Chloe Smith

HIGH summer flows of cold water down the Goulburn River are killing almost a third of young native fish before they can reach 12 months of age, according to fisheries research.

Victorian Fisheries Authority chief executive Travis Dowling said he was concerned the cold water being flushed down the Goulburn in the midst of summer “was negating the impact of environmental flows from September-October”.

“It’s incredibly disappointing these cold water flows are doing so much damage to the fishery when so much work has gone into stocking and restoring (river) habitat,” Mr Dowling said.

Arthur Rylah Institute and University of Melbourne researchers found doubling summer flows slashed the number of Murray Cod surviving their first year by 29 per cent.

Water Minister Lisa Neville has tried to stem the flow of cold water down the Goulburn each summer to 50 gigalitres a month, but has been forced into a backdown due to irrigation demand.

The Murray Darling Basin Authority has ignored Minister Neville, calling for even more water out of the Goulburn to quench Lower Murray irrigators’ thirst this month – from the Sunraysia to the South Australia’s Riverland.

Up until yesterday almost 58GL had flowed past the Lower Goulburn’s McCoy Bridge meter for January.

Water resource managers say the MDBA has been forced to source Goulburn water, given the Darling River has run dry and the Murrumbidgee storages are running low, with Blowering Dam at 38 per cent and Burrinjuck at just above 30 per cent full.

The Murray Darling Basin Authority has previously come under criticism for failing to hold more water in reserve in the Menindee Lakes, after allowing 2016-17 Darling River floodwaters to sweep down to South Australia’s Lower Lakes.

Mr Dowling said all native species were being affected by the cold summer flows, which killed eggs and young vulnerable Macquarie perch, Murray and native Trout Cod.

“The evidence for this is 50 years of cold water flows (in the Goulburn River reach) from Alexandra to Seymour where native fish populations are extinct,” he said.

“The VFA has significant concerns about cold water impacts on the Lower Goulburn as a result of inter-valley transfers to the Murray and we will be raising it with the MDBA.”