Carp diem: Fears over mass spawning

Jan 8, 2023

Too many to count: Thousands of carp are concentrated in a drainage line on Jeremy Morton's property in Moulamein. Photo by Contributed

Footage has emerged of mass carp spawning events in rivers across the Murray-Darling Basin, causing fear of an ecological disaster.

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The carp explosion comes after widespread flooding caused hypoxic blackwater events, providing the ideal breeding environment for the introduced species.

Federal agencies have described carp — which now make up 80-90 per cent of fish biomass in the basin — as one of the worst introduced species in Australia, due to the destructive impact they have on water quality and on native fish species.

New South Wales Irrigators Council (NSWIC) chief executive Claire Miller said the impact of carp was one of the greatest ecological threats to our waterways.

She called on water authorities to act promptly in addressing this threat.

“The number of carp spawning is jaw-dropping. It looks like the water is bubbling,” Ms Miller said.

“Carp control is essential to avoid these floods leaving a lasting legacy of ecological degradation for years to come thanks to carp in plague proportions.”

Moulamein irrigator Jeremy Morton posted footage on social media last week of thousands of carp in a drainage line on his property.

Speaking to the Deniliquin Pastoral Times, Mr Morton said it was the first time he had seen mass spawning to this extent.

“We’ve been trying to get yabbies out of the lake next to this drainage line, and every time we put the net in we’re pulling out at least 50 carp,” Mr Morton said.

"They were spawning and breeding when the water was up and now that it is receding, they are concentrating in areas because they are still trying to move upstream.

“We’ve got a situation where we have dead native fish and a carp boom. This just demonstrates that we need to start thinking about how we’re going to control carp numbers as we continue with the basin plan.”

Ms Miller said the carp eruption would require the Basin Ministerial Council to look past the simplistic just-add-more-water approach.

“No amount of buybacks will fix the basin’s biggest ecological threats,” Ms Miller said.

“If we are serious about looking after important ecosystems then degraded habitat and water quality should be priorities for action.”

More than 2100 billion litres of water has been taken out of the irrigated agriculture pool as a result of the water policy, more than four Sydney Harbours.