Three New ‘Unwanted Organisms’ In New Zealand

21 July 2000

THREE NEW ‘UNWANTED ORGANISMS’ IN NEW ZEALAND

A frog and two fish species have joined the growing list of New Zealand’s least wanted introduced species.

Last week the Department of Conservation (DOC) declared the Eastern banjo frog, the mosquito fish and the European (koi) carp as “unwanted organisms” under the Biosecurity Act 1993. This means that action can be taken using the enforcement powers under the Biosecurity Act to prevent or reduce the spread of these species. It is illegal under that Act, release, buy, sell or breed them. where a person knows or suspects that the animal is one of those species. The only exception is if the person gets a written permit first. It was already an offence to liberate them into national parks, other public conservation land , and reserves.

The koi carp and its hybrids were designated a noxious fish species 20 years ago. Since then it has been illegal to rear, raise, hatch or consign those fish without first getting a permit from the Department of Conservation. It has also been , and still is, an offence to keep in captivity or to possess any mosquito fish without prior written approval.

“This trio are further examples of species that have been introduced to New Zealand, and which now threaten our unique natural heritage,” said DOC Biosecurity Chief Technical Officer, Geoff Hicks.

“The ‘unwanted organism’ status will allow Government agencies to take action against the species, if and when it is considered necessary.”

Dr Hicks said it was also a reminder to the public to be aware of the threat these species present. “Both the mosquito fish and koi carp have recently been recorded in the South Island for the first time, and both appear to have been spread by people emptying fish tanks into the wild without realising the consequences of their actions.”

The new ‘unwanted’ status will not affect the commercial fishers who have permission to remove and kill koi carp from parts of Waikato and Auckland.

The Eastern banjo frog (Limnodynastes dumerilii) was first found in New Zealand just nine months ago, and has already been subject to a joint Ministry of Agriculture and Forestry, Auckland Regional Council and DOC eradication attempt.

The frog, named for its unusual loud ‘plonking’ call, is known to eat a wide range of insects, small frogs and skinks. It is also known to carry the chytrid fungus which has been implicated in the global decline of frogs and other amphibians.

The mosquito fish (Gambusia affinis), a native of North America, was first introduced to New Zealand for mosquito control more than 70 years ago, but with little evidence of success. Instead, the mosquito fish has made more of an impact on native insects and fish populations than on mosquito numbers.

Since the 1980s, there have been controls on holding, transferring and releasing the mosquito fish but its new ‘unwanted’ status means environmental managers have extra powers to limit its spread. At present it is found throughout Northland, the Waikato, Bay of Plenty, Hawke’s Bay and Wellington. Earlier this year, they were also reported from Nelson for the first time.

Koi carp (Cyprinus carpio) pose a significant threat to the health of New Zealand’s freshwater ecosystems by uprooting water plants, lowering water quality and eating insects and other young fish.

Until recently they have been found only in the North Island, but a new infestation in Nelson has also been the subject of a joint DOC and New Zealand Fish and Game Council eradication attempt. Action to declare them unwanted is to prevent their spread to the South Island.

For further information please contact Rachel Garthwaite, DOC Science and Research, 04 471 3213, or Geoff Hicks, Biosecurity Chief Technical Officer (Conservation), 04 471 3063.

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