Koi Carp – "possum of the waterways"

29 October 2007

Koi Carp – "possum of the waterways"

On the weekend of 3 – 4 November bowhunters from throughout New Zealand and beyond will gather at Rotowaro, west of Huntly to participate in the annual New Zealand Bowhunters Society’s World Koi Carp Classic.

Now in its seventeenth year this unique event combines a traditional and unusual form of hunting with ongoing research into a noxious pest fish, while making a contribution to its management.

The event also raises awareness of the koi carp’s destructive effect on freshwater habitat, where native flora and fauna such as inanga, eels, kokopu and trout are displaced due to habitat change. Commonly referred to as the “possum of the waterways”, fish taken over the two days of the Koi Carp Classic are weighed and measured providing invaluable data to researchers keen to halt its spread in New Zealand.

New Zealand Bowhunters’ Society President and host of the Koi Carp Classic, Allan Metcalfe, explains this recent addition to our freshwater fisheries as an ornamental species imported by aquarists and pond keepers. He attributes its current feral status and spread from the late 1970s to escapes and unpermitted releases by course fishermen.

“It’s likely the North Waikato lakes were never crystal clear but they should be, especially given all the work being done to fence off waterways. The reality is that they aren’t and habitat destruction by koi is a big factor in this. The aquatic plants just can’t regenerate quickly enough to oxygenate and sustain freshwater habitat,” says Allan.

“People don’t realise how widespread koi are and how fast they can reproduce. Current research shows that a single female can produce over a million eggs in a single spawning. Some females can spawn three times a season and they have an average lifespan of 12 years.”

In the past Koi Carp Classic hunters succeeded in taking large numbers of this noxious fish during the event, with a 2004 record of 3500 fish weighing a colossal 8.6 tonnes, however, Allan is the first to acknowledge this makes but a dent in the total population.

“The Classic is more about raising awareness and two critical messages. The first is about how destructive this fish is. The second is trying to get the message out there not to shift these fish around; maybe then they can be contained.”

The Department of Conservation‘s main focus is the containment of pest fish and their unauthorised movement outside of the agreed containment area.

“Legislation requires people to kill koi carp upon catching them as it is illegal to possess live fish. People who are caught with live fish can incur heavy fines upon prosecution.

“Alongside the obvious consequences of habitat destruction there’s the simple waste of funds and resources that could be channelled into positive pest fish management,” says DOC spokesperson Jack de Thierry.

The Department of Conservation along with the major sponsor, Solid Energy, are right behind the Koi Carp Classic because it raises public awareness of this serious aquatic pest.

Members of the public are welcome to attend the Koi Classic at 292 Ginn Road, west of Huntly with weigh-ins from 5pm on Saturday and 3pm on Sunday providing the best times to see hunters return their catches to the scales. Money raised from the sale of fish berley will be donated to the Huntly Rotary Club’s current charity. Berley purchasers should bring their own containers.

ENDS

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