Viewpoint

Possum Control Goals Flawed

The March 1992 issue of Sci-Tech, the newsletter of the Ministry of Research, Science and Technology, included an article on the development of a National Science Strategy (NSS) for the interlinked problems of possums and bovine tuberculosis (Tb). Some of the statements in that article are alarming and demand further comment.

According to the article, the impetus behind the NSS concept is to develop "a portfolio of research to plug gaps" in particular research areas, and "to allow for improved coordination of, and a stronger strategic focus for, Crown-funded research programmes of national importance".

As an overall guideline, this approach seems sensible. My concern centres on some of the conclusions reached at a recent meeting called to develop the NSS for possums and Tb. The article states that "scientists have given themselves up to six years to stop the spread of bovine Tb, and up to 16 years to wipe out the wild animals that carry the disease." More specifically, the NSS committee will:

• coordinate and promote research to stop the spread of bovine Tb (one to six years)
• roll back the distribution of Tb in animals (three to 12 years)
• protect conservation values from possums (three to 12 years)
• wipe out possums (six to 16 years)
• wipe out wild animals that carry Tb.

As a scientist currently working in the field of wild animal management, I find it disturbing to see clearly unachievable goals established as the guiding theme behind this whole problem of possums and bovine Tb. Undoubtedly, possums are one of our most serious problems, both for their role in the transmission of bovine Tb and its effects (current and potential) on a major part of our agricultural sector, and also for their impacts on our indigenous flora and fauna.

The nature and scale of these problems require the coordinated and concerted approach that an NSS can offer. However, the policy and goals contained in such an NSS must be credible and -- most importantly -- achievable. If the goals are not achievable, then the strategy is destined to fail from the outset.

In essence, most wild animal pest problems have three basic elements: the resources at stake, the pest, and the people who value the resources and benefit from any pest control.

The foundation of good pest management is to recognise the relationships, sometimes complex, between these three elements and ensure that the control strategy is goal-oriented, that the goal is the protection of the resources and not the killing of pests per se, and that those who benefit from the control pay for it.

I would like to pose the following questions. While they do not cover all my concerns with the proposed NSS, they highlight several areas where it seems obvious that the NSS has serious shortcomings.

Given that bovine Tb has been detected in a wide range of mammals, including possums, red deer, sika deer, wild pigs, goats, ferrets and stoats, does the NSS committee really envisage that it can and will eradicate all those species within the 16-year timeframe it has set?

Obviously, given an unlimited quantity of funding and other resources, almost anything is possible, but to say that we are going to eradicate at least seven species of wild animals from New Zealand seems an absurd misdirection of funds and effort. I would suggest that we have neither the technology nor the means of delivery to achieve such an objective.

Does the NSS strategy represent the most effective use of money?

As scientists in the "new environment" of accountability and output-driven research, we have an obligation to ensure that public monies are spent in the most efficient and effective manner. I suggest that the proposed strategy does not comply with this objective. In addition, since such a strategy would require vast sums of money (part of which is certain to come from Government coffers), what other research and management areas will suffer as a result?

Have all the related issues that impinge on the NSS been fully considered?

For example, given the wider goal of eradicating all wild animals that carry Tb, what of the estimated 50,000-plus big game hunters in New Zealand? Besides representing a significant recreational group, the hunting-related economy has been estimated to be worth over $40 million annually.

Clearly the problem faced by the NSS committee is a complex and difficult one. However, I suggest that rather than setting "pie-in-the-sky" goals, we should direct our efforts to formulating appropriate strategies within the framework of good pest management -- realistic, achievable and measurable goals.

Perhaps some lateral thinking is called for. Control strategies currently focus on creating a buffer around the wild animal populations (principally possums) that can act as a Tb reservoir and a source of reinfection for cattle. This control aims to reduce wild animal densities along the forest margin interface between those populations and adjacent farmland.

Given the seemingly intractable extent of this problem (since the adjoining forest areas are extremely large in many cases and act as a constant source of new animals), has any consideration been given to creating a different kind of buffer zone, on the farmland rather than in the bush, by removing cattle from areas within some pre-determined distance of major reservoirs of infected wildlife. Given the huge scale of the wildlife problem, management of the domestic component of the problem could be a cheaper option in some areas, although I am sure such measures would initially meet with strong resistance from farmers.

We should resist the temptation, however admirable the final objective, of locking ourselves into a strategy that, if taken literally, will require millions of dollars to be poured into what will certainly turn out to be a bottomless pit!

Wayne Fraser is a scientist with the Weeds & Pest Division of Landcare Research NZ Ltd.