Federal agencies describe carp, which now make up 80-90 per cent of fish biomass in the Basin, as ‘one of the worst introduced pest species in Australia’ due to their degradation of waterways.
NSW Irrigators Council CEO Claire Miller said 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”.
“The number of carp spawning is jaw-dropping. It looks like the water is bubbling,” she said.
“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.”
Moulamein irrigator Jeremy Morton posted footage on social media last week of clouds of carp in a drainage line on his property, near the Neimur Creek.
The video was captioned “this is just one little tiny spot. Imagine how many countless billions have actually bred over the last few months; unbelievable”.
Mr Morton told the Pastoral Times it is the first time he has seen spawning is such large number.
"The were spawning and breeding when the water is up, and now it is receding back they are concentrating in areas because they are still trying to move upsteam,“ Mr Morton said.
“Native fish tend to go backwards with the flow because they know it is going back to the river.
“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 carps.
“Carp tend to cope better in hypoxic blackwater events, so we’ve got a situation where we have dead native fish and a carp boom.
“It demonstrates that we need to think about how we’re going to control carp numbers as we continue with implementing the Basin Plan.”
Ms Miller agreed that this explosion of carp should 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 has been taken out of the irrigated agriculture pool as a result of water policy. That amount is equal to more than four Sydney Harbours.
The NSWIC says this has reduced diversions for farming, towns and industry from 35 per cent of inflows to just 28 per cent, well within global standards for a healthy level of water use.
16°C