Kangaroo Lake fish kill: Spring’s black water legacy

The nutrient-rich black water diverted from last October’s floods into the Kerang Lakes has led to a major fish kill.

These huge adult Murray cod could have layed 50,000 eggs each for the next decade.

The legacy of last October’s Loddon Valley floods has wiped out 70 one-metre-long Murray Cod and thousands of other fish in Kangaroo Lake, says recreational fishing lobby VRFish.

VRFish chairman Rob Loats said the kill could be traced back to the massive wave of black water that flowed off the Loddon River floodplain, some of which Goulburn Murray Water corporation diverted into the Kerang Lakes last spring.

“Why they drew it off (into the lakes) I don’t know,” Mr Loats said.

He said the nutrient rich black water had been followed by blue-green algal outbreaks in summer, which had then turned over during the recent heatwave, leading to a dramatic drop in dissolved oxygen levels that killed the fish.

The Weekly Times is awaiting a response from GMW on whether it was forced to divert water into the lakes to mitigate flooding elsewhere or to help maintain water quality in other parts of the system or Murray River.

But the fish kill could not have happened at a worse time for Kangaroo Lake Caravan Park manager Clive Patullock, who was busy this morning pulling rotting cod, golden perch, carp and redfin carcasses from the water, in bid to clean up the mess in the leadup to the Easter break.

Metre long Murray Cod rot within a pile of fish dragged out of Kangaroo Lake.

“We’re really worried because we can’t use the (lake) water and are having to cart it in at $220 a tanker,” Mr Patullock said. “I’m hoping we can get support from GMW.”

In the meantime an appeal for help has led to volunteers streamign in from Swan Hill and surrounding areas to help out, collecting 16 trailer loads of dead fish.

Shovels and and tractors were used to clean up the fish kill

Volunteers collected 16 trailer loads of dead fish.

Mr Patullock said GMW had commited to divert fresh water into the lake from the Torumbarry system, which he expected would help get the lake cleaned up for Easter.

Mr Loats estimated the 70 one-metre-long cod that died could have delivered well in excess of $10 million worth of fingerlings into the Kerang Lakes and wider river system.

He said each fish could breed for at least 10 years, producing a minimum of 50,000 eggs annually, of which 10 per cent could survive to the fingerling stage, each worth $4 to $5 each.

“Then there’s the recreational fishing value,” Mr Loats said.

“It’s awful and very emotional for everyone involved and we want answers from GMW”.

GMW water delivery general manager Warren Blyth said “in late 2022, floodwater was diverted to the Kerang Lake system to mitigate residential flooding.

“This was not black water,” he said. “During the 2022 floods, water was diverted to the Kerang Lake system to mitigate residential flooding.

“This included Third Reedy, Lake Tutchewop, and Lake Mannaor storages, which usually do

not have water diverted to them.

“Black water can occur after a flood or when water becomes stagnant. Black water occurs

naturally, often following intense rainfall in warmer months and can lead to deoxygenated

water and fish deaths.”

Dead fish line the shore of Kangaroo Lake

The kill comes just days after at least a million fish died in the Lower Darling.