Date: 27 January 2012
The Department of Conservation (DOC) is conducting surveillance in Whakatane/Opotiki rivers to identify koi carp and is asking the public to report any sightings.
Koi carp have a significant effect on freshwater environments, native species and the whitebait, eel and trout fisheries.
From previous appeals to the public for sightings of koi carp some potential sites have been identified says Ranger, Biodiversity Threats Peter Livingstone.
“They 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 significant period, so we need to keep a constant watch for them.”
“DOC staff and contractors will be undertaking pest fish surveillance, both in the urban and rural areas from this month over the Summer period.”
“Every effort will be made to contact adjacent landowners when staff or contractors are in and around waterways”, says Mr Livingstone.
In comparison grass carp are present in several of the larger cleaner canals and drains in the northern Rangitaiki Plains. They are quite distinctive from koi carp or gold fish, a lot larger in size and predominantly grey or silver in colour.
Koi 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. They are easily transferred as adults or eggs into new waterways. As prolific breeders, their numbers build rapidly so they can readily “take over” new sites.
They 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. Barbels are the most obvious feature, which distinguish the carp from other species such as goldfish. Mostly live in sluggish, often weedy streams and around the shallow areas of lakes and lagoons.