VEXED QUESTION: European carp are a huge problem in many Australian waterways.
VEXED QUESTION: European carp are a huge problem in many Australian waterways. Lyndon Keane

Will the $15 million carp 'solution' actually work?

IT'S taken a long while for me to get to grips with the koi carp herpes virus, so to speak.

I've never been one to jump on bandwagons or take statements at face value.

I try to find out as much as I can about an issue as serious as this one.

I first encountered European carp in the late 1970s on the Murrumbidgee River below Burrinjuck Dam.

We approached the river at Childowlah with high hopes of our usual brown and rainbow trout, Murray cod, golden perch and redfin.

We met uncountable carp in every muddy pool and caught other species only in the runs and rapids between pools.

A later cod expedition through the Murray's redgum forests around Gunbower Island showed just how severe the carp plague could be.

In the mid-1980s, I heard about some dickheads releasing Euro carp into Horseshoe Lagoon at Casino for "sport” and, about the same time, we had an unregulated runoff from a koi breeding pond at Knockrow that spewed fingerlings into the Emigrant Creek system.

Together with the "liberation” of pet goldfish into the local waterways over the years, this triple whammy of carp species on the Richmond floodplain took off in river water compromised by low pH, high turbidity and ever more regular crashes in dissolved oxygen.

News eight or nine years ago that a koi herpes virus had the potential to wipe out carp looked like the silver bullet that our waterways needed.

CSIRO led the charge, headed by the same people who handled the rabbit calicivirus.

Koi herpes tests on 13 species of native fish, reptiles, mice and chickens produced no ill-effects, leading the CSIRO to conclude that this family of herpes was species-specific.

Things gradually gained momentum until Barnaby Joyce's weird "Caaarp!” speech in the House of Representatives in 2016 and his appointment of "The Carpinator”, Matt Barwick, an environmental science graduate from the University of Canberra and Federal and State fisheries bureaucrat and consultant.

Earlier this year, before they'd tied up Barnaby underneath the tankstand after he'd slipped the leash and gone mad, everything was meant to be good to go in the "caaarp” world by this December.

The plan was to release the virus into the Lachlan River, from where it was to spread via water and birds throughout the Murray-Darling Basin within months.

After an incubation period of up to a week, it takes around a day for a fish to suffocate and die due to gill damage.

But in his May update, Carpinator Barwick wrote: "The NCCP was set an initial deadline of December 2018 to deliver recommendations to governments. While we still have six months remaining, I want to assure you that deadlines will not shape outcomes.”

More time was needed to review research, people were telling him.

So it may well be that the plan will not run headlong to a release date next year - let's hope not, anyway.

This is way too irreversible to let politicians decide.

CSIRO has made soothing noises when questions arise concerning the almost overnight appearance of an estimated 55,000 tonnes of dead carp in NSW rivers and drinking-water reservoirs but there have been widespread doubts about these issues.

Once the virus is released it can't be removed - but not every carp will die.

Estimates are that within 10 years the virus-resistant fish will breed back up to 60% of the current population and the CSIRO is already planning for more virulent virus strains.

Barwick says getting rid of carp will create a window, before they breed back up, to improve river health and native fish stocks to prevent carp re-establishing domination of the system.

The project in its present form is costed at $15 million.

What do we get for that?

The water is still likely to be muddy. Studies show no links of carp with changes in turbidity, which are mainly associated with water level changes, local runoff and surrounding land use practices.

The CSIRO says: "The release of the carp herpes virus will also provide an opportunity to simultaneously restore native fish habitats, improve water quality and restore migratory pathways for native fish, to help ensure that native fish thrive once carp are removed. This, in turn, will help ensure that carp numbers don't recover.”

But that's not part of the $15 million and doesn't address the crux of the problem.

Two of the foremost aquatic veterinarians in the country have separately suggested that we're putting the cart before the horse.

West Australian aquatic vet and veterinary pathologist Dr Richmond Loh, and Northern Rivers fish vet Dr Matt Landos, both pose the question: are carp and goldfish a cause - or the effect - of environmental degradation?

They suggest carp are proliferating and native species are declining because of pollution and habitat alteration (eutrophication, salinisation, acidification, land clearing, draining), in-stream barriers, and water abstraction (surface and ground water, legal and illegal).

Locally, the effect of the koi herpes virus on the koi/goldfish/euro carp hybrids that proliferate here is an unknown quantity.

It kills euros and koi but not goldfish, and when Barwick held the Lismore meeting of his national carp roadshow earlier this year, he was noncommittal on its local effectiveness.



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