1. Introduction

Since the Australian brush-tailed possum (Trichosurus vulpecula) was officially recognised as a major pest in New Zealand in 1947 (when the Government legalised the use of poisons for possum control), several control methods have been developed. Traps and poisons are the main methods of control for possums, which now occupy all of mainland New Zealand except for parts of Fiordland. For over 50 years, one of the most effective control methods in a range of environments has been the use of 1080. Because of its cost-effectiveness it is widely used by the two major agencies that control possums: the Animal Health Board (AHB) and the Department of Conservation (DOC). These two agencies use 1080 for different reasons. This reflects their different responsibilities and priorities with respect to possum control.

This discussion document has been prepared by AHB and DOC to provide information on the use of 1080 and how it 'behaves' when released into our environment.

The Animal Health Board

AHB is the agency responsible for New Zealand's programme to eradicate bovine tuberculosis (Tb) from farmed cattle and deer herds, and wild animals. The programme operates under the auspices of the National Pest Management Strategy developed in accordance with the Biosecurity Act 1993. AHB is a Management Agency, as defined by the Biosecurity Act. AHB is a non-profit making, incorporated society whose membership reflects the major stakeholders and funding interests in the Tb pest management strategy. The control and eradication of bovine Tb in New Zealand largely depends on controlling the wildlife sources of the disease. These are mainly possums. Possum and other wildlife control programmes under the Tb strategy have expanded in recent years. In the year to 30 June 2003, AHB spent over $55 million carrying out possum control and some ferret control, on 7.8 million hectares. AHB contracts the management of possum control programmes to regional councils in most regions, but also has management contracts with private companies in the Otago region and Tasman District.

The Department of Conservation

DOC is responsible for managing the 30% of New Zealand's land area that has protected status, such as national parks, reserves and conservation land. It also plays a major role in implementing the New Zealand Biodiversity Strategy, launched by the Government in 2000.

The third goal of this Strategy is to "Halt the decline in New Zealand's indigenous biodiversity." This goal is linked to New Zealand's international obligations under the Convention on Biological Diversity to conserve our indigenous (native) ecosystems and species.

Field staff and research scientists within DOC work towards this goal in a number of ways. Many are focused on managing plant and animal pests to improve the condition and health of native ecosystems and the survival prospects of threatened species. As a major part of this effort, DOC currently spends about $14 million of its pest management budget on possum control. Significant amounts are also spent controlling stoats, rats, goats, deer and other pest species. Despite increasing the amount spent on possum control, the area currently under sustained management for possums is 15-18% of conservation lands, for the 2003/2004 period.

The use of 1080 toxin to control possums for conservation purposes is not preventing the decline in the overall condition of our indigenous forests. The introduction of pest species, the clearances and fragmentation of the natural vegetation led to inevitable declines in numbers of native species as pests invaded the remnant forests. The silence of our native forests is a legacy of the introductions and the increasing silence will continue unless we reverse the onslaught of pests on a massive scale.

1080 is one of the most effective tools we currently have to restrict the deterioration in biodiversity condition but only on a relatively small scale. We cannot prevent the ongoing deterioration on a landscape scale. Further loss of indigenous species is inevitable as habitats continue to shrink and pressure from pest species continues to affect the ability of native species to maintain their numbers, let alone expand.

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