Pest koi carp found in Kaipara

Tara Moyle, from Kaiwaka School, won a poster competition calling for the eradication of koi carp.

Koi carp are rearing their ugly heads in the Kaipara district and they're not wanted there or anywhere else.

The pest species, possibly accidentally introduced to New Zealand with goldfish in the 1960s, have been found in farm ponds and rivers in the Kaipara catchment.

Koi carp degrade water quality, cause bank erosion, breed prolifically and out-compete native species like eels and whitebait for food and habitat. To add insult to injury, koi carp don't taste very good.

Department of Conservation staff have been talking to Kaipara landowners, organising roadside signs and teamed up with the Whitebait Connection to deliver koi carp education programmes in local schools.

Students were invited to design a poster to be displayed in their community, with Tara Moyle from Kaiwaka School winning the competition and receiving an iPad Mini for her efforts.

Sometimes koi carp are intentionally - and illegally - released into ponds to clean out weeds, where they feed like a vacuum cleaner sucking up everything in their way and undermining banks.

In 2012, a north Kaipara farmer contacted the Northland Regional Council (NRC) after finding koi carp in a pond. NRC then got DoC involved.

"We tried netting the fish out, but they hid down in the mud so we had to drain the pond to get them all. There were literally hundreds of them," Kauri Coast DoC ranger Darren Jones said.

Whitebait Connection also played a part.

"The really scary thing with that particular case was that it was only 200 metres from a river that leads into the Kaipara.

"All it would take was a flood or slip and they'd be in the Kaipara faster than we could blink an eye," coordinator Kim Jones said.

"We know that sediment is already a problem in the Kaipara Harbour, with recent research showing that it is making snapper mutate to cope with the dirty water.

"We certainly don't want to make this worse by having koi carp in our waterways."

Anyone who knows of koi carp in ponds, drains or waterways should contact DoC on 0800 362 468.