Introduction

The Department of Conservation (DOC) is cranking up efforts around Northland to identify and get rid of these tough, persistent pest fish and it needs public help to do so.

Date:  11 March 2009

When is a goldfish not a goldfish? When it’s a nasty koi carp!

Koi carp.
Koi carp

The Department of Conservation (DOC) is cranking up efforts around Northland to identify and get rid of these tough, persistent pest fish and it needs public help to do so.

Previous appeals for sightings of koi carp have had a great result, says DOC spokesperson Amy MacDonald, with summer being a critical time to help contain fish spread.

“Koi carp spawn in spring and summer with females producing several hundred thousand eggs. The carp are very robust and can survive out of the water for a long time if kept moist, so we need to keep a constant watch for them.”

The carp are pests because they cause water quality degradation by mixing up sediment on the bottom of waterways; eat aquatic plants, insects and small fish, making waterways unsuitable for native fish and trout and are easily accidentally transferred as adults or eggs into new waterways. As prolific breeders, their numbers build rapidly so they can readily “take over” new sites.

“We’re asking anyone who thinks they’ve seen koi carp to contact DOC immediately so we can confirm the report and then decide on management options,” says Ms MacDonald. “Whatever we propose to do is agreed with landowners first. The idea is to help landowners with water quality on their own properties as well as look after freshwater ecosystems in general.”

DOC has already eradicated two koi carp populations from ponds on private land at Waipu and Houhora and is working towards a goal of either eradicating or containing remaining populations.

Koi carp resemble large goldfish except for two pairs of barbels or feelers at the corners of their mouth. Their colours vary, often with irregular blotches of black, red, gold, orange or pearly white and they can grow to about 75cm. The barbels are an obvious feature, which distinguish the carp from other species such as goldfish.

They mostly live in sluggish, often weedy streams and around the shallow areas of lakes and lagoons.

“A simple phone call or e-mail is all it takes and we can get someone out to a property very promptly,” Ms MacDonald says. “Action isn’t always possible but it’s important to know where the carp are for a comprehensive management perspective.”

To report koi carp phone +64 9 470 3300 or e-mail northland@doc.govt.nz, putting the words “pest fish” in the subject line.

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