ACCORDING to a newspaper report, recent floods affecting the Murray Darling Basin have had an adverse effect on cod numbers along stretches of the Murray River.
The cause of the cod decline is believed to be attributed to blackwater, resulting from large areas of floodplain covered in layers of leaf litter for many years, becoming flooded. The blackwater removes oxygen from the water, making it toxic to aquatic life.
The Murray Darling Basin Authority told The Daily Telegraph that blackwater had affected 700km of the Murray River in the wake of the floods.
“It has been the worst in living memory, it even extended down into South Australia, which is unprecedented,” a MDBA spokeswoman said.
There had been reports of thousands of freshwater crayfish escaping the blackwater by climbing bankside trees, but Murray cod hadn’t been able to escape with some floating to the surface dead.
Well known cod angler and fishing writer Rod MacKenzie, said he could not verify one large cod being caught by anglers for seven months in the Robinvale area after the blackwater event.
“It’s becoming clearer that these fish are all but gone,” Mackenzie told the Telegraph. He said the massive fish kill was heartbreaking because Murray cod had been increasing in numbers and size every year.
Claims the blackwater was the result of “environmental water” being pumped into the surrounding wetlands, lagoons and river red gum forests several months before the floods have been rejected by the MDBA.