Footage is emerging of mass carp spawning events in rivers across the Murray-Darling Basin in the wake of widespread flooding, raising fears of an ecological disaster in the making.
Federal agencies describe carp, which now make up 80-90% of fish biomass in the Basin, as ‘one of the worst introduced pest species in Australia’ due to their degradation of waterways.
“The impact of carp on habitat and water quality is one of the greatest ecological threats to native fish recovery and healthy rivers in the Basin,” said NSWIC CEO, Claire Miller.
“The number of carp spawning is jaw-dropping. It looks like the water is bubbling.
“We call on the authorities to act promptly. 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.
Irrigator Matt Whittaker posted on social media, sharing that: “Every body of water whether it be the river or floodplain is chockers in Macquarie downstream of Gin Gin”.
Meanwhile, in the southern Basin, irrigator Jeremy Morton posted footage of a small creek, saying: “This is just one little tiny spot, imagine how many countless billions have actually bred over the last few months, unbelievable.”
The event will put pressure on the Basin Ministerial Council to look past the simplistic ‘just add more water’ approach when it considers the next steps on the Murray-Darling Basin Plan.
The carp spawning follows hypoxic blackwater events across the Basin, in which deoxygenated water from widespread flooding caused fish deaths.
“No amount of buybacks will fix the Basin’s biggest ecological threats, with rampant destructive feral species killing native species, wrecking their habitats and water quality,” said Ms Miller.
“If we are serious about looking after these important ecosystems, a health check would quickly reveal invasive species, degraded habitat and water quality should be the priorities for action.
More than 2100 billion litres of water have been taken out of irrigated agriculture (or over four Sydney Harbours). This has reduced diversions for farming, towns and industry from 35% of inflows to just 28%, well within global standards for a healthy level of water use.