The Department of Conservation is seeking public help to determine the distribution of koi carp in Northland.
Koi carp originated from Asia; and were first recorded in NZ in the 1960’s. They have become established in the Auckland
and Waikato regions, where they are causing widespread problems in aquatic ecosystems.
Koi carp breed prolifically and can tolerate a wide range of environmental conditions, which means that once introduced
they can quickly become the dominant fish in water bodies and can quickly colonise upstream and downstream habitats.
They have a huge and significant impact on rivers and ponds, and affect water quality by disturbing the bottom of
streams and ponds. They also destabilise river and pond banks, and destroy habitat for native fish and waterfowl. Koi
carp have be known to graze pasture during floods, and to damage vegetation planted for erosion control.
Koi carp are a large freshwater fish, which can reach up to 750mm long and 10kg in New Zealand waters. Their colour is
highly variable, but they tend to be orange; sometimes with black or white markings. A distinguishing characteristic is
two short, whisker-like barbels near each corner of the mouth.
Koi carp have so far been recorded from only two sites in Northland; a dune lake on the Pouto Peninsular, and the
Whakanekeneke River. Koi carp are classified as a noxious species under the Freshwater Fisheries Regulations, and have
recently been declared an “unwanted organism” under the Biosecurity Act 1993.
The Department is now working to determine how widespread koi carp are Northland, and will then assess whether they can
be eradicated from the region. Anyone who thinks they know of somewhere where there are koi carp in ponds or rivers in
Northland should contact their nearest Department of Conservation office with details.
The Department is also interested in records of other exotic fish such as catfish, tench, and rudd. Eel fishermen and
farmers have already been supplying valuable information about the distribution of some of these species.
DoC is keen to ensure that koi carp are eradicated from Northland before they spread out of control. These fish will
have a devastating effect on our natural waterways, and we want to work with landowners on getting rid of this threat.