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.

- NORTHERN ADVOCATE

Pest koi carp found in Kaipara

Invasive species found at Boundary Dam

June 20, 2014

Kelly Running

For hundreds of years koi fish, a variety of carp, have been a domestic fish. Bred for their colour koi fish are a popular choice for introducing to an ornamental backyard pond because koi seemingly glow beneath the water and are often considered a relatively pretty fish.

The situation becomes ugly, however, when koi are either released or make their way to the wild due possibly to floods.

Koi, are an intrusive fish, which can drastically alter ecosystems. Koi being a type of carp are a cold water fish that stir the floor of the lakes they find themselves in which muddies the water and can destroy aquatic vegetation, which degrades the water they are in forcing other species to struggle in what had been their natural environment.

Locally, just south of Estevan, at Boundary Dam, Landon Polk and Chelsea Greening, happened upon what they thought were carp as the two species do look similar except for the koi’s unique colourings. The couple were out bow fishing and upon seeing the large fish took aim.

“While at Boundary Dam near the hot water return we spotted a few large fish that we thought were carp,” Chelsea explained to The Observer. “We got the bow, which is equipped for shooting fish, and were able to shoot one, to our surprise it was not a carp. We had a conservation officer send the picture of the fish away to Saskatchewan Fisheries and it was confirmed as a koi fish.”

After looking into this Chelsea and Landon discovered that koi pose a threat to the ecosystem.

“They stir up the bottom making the water murky which also increases nutrient levels and algae concentrations, which also contributes to erosion. They also feed on and remove aquatic plants, they prey on invertebrates, native fish and their eggs, causing a competition for the native species.”

It is essential for Conservation Officers to remove these fish from the lake before great destruction is done to Saskatchewan native species. Thus, if anyone catches one they are not to return it to the water.

“Landon… has now shot two of the Koi out [of] the lake which both weighed around 25-30lbs,” Chelsea explained.

“As far as we know we are the first ones to have [gotten] one of these fish from out of the water, although we know many have spotted them, since they hang out near the hot water return, come close to shore, and kind of look as if they are glowing in the water.”

Invasive species found at Boundary Dam