Foreword by Hugh Boyd
This Occasional Paper is unusual in consisting of three separate but related papers. The analysis by Dr. Charles Francis of the relative impact of hunting in the spring, compared with the conventional hunting seasons in fall and winter, was originally commissioned for the purpose of improving managerial understanding of the impact of spring hunting by indigenous peoples in northern Canada. This updated version is immediately relevant to the questions addressed in the other two papers. The paper by Cooke et al. is a greatly revised and expanded version of one read by Professor Cooke at an international meeting on goose management held in Zwolle, Netherlands, in November 1997. In it, Cooke commented on the model and the choice of parameters that had been used by Rockwell et al. (1997) in a paper published in Arctic ecosystems in peril (Batt 1997), which provided the underpinning for the argument in that report that a great increase in the hunting kill of mid-continent Lesser Snow Geese Anser caerulescens caerulescens (hereafter referred to as Snow Geese) was required first to slow down and then to reverse the rapid and sustained increase in the numbers of those geese. The chief purpose of such a reduction was to end the locally severe damage being inflicted by the geese on the vegetation of coastal wetlands along the west side of Hudson Bay. Cooke argued that, although the model used by Rockwell et al. (1997) was basically sound, they had used obsolete or erroneous values for some of the key parameters. He showed that if updated values were used, the estimated numbers of adult geese that it would be necessary to remove from the population in order to end its growth might be much larger than Rockwell et al. (1997) had suggested. Having heard Cooke's paper, I thought it would be of value to publish it, after peer review, so that administrators and biologists in the relevant regions of Canada and the United States could consider the practical implications of the widely different alternative projections being put forward. I also encouraged further debate between Rockwell and Cooke and their associates, in the belief that it might help to clarify the issues. Meanwhile, the recommendations by Batt (1997) have been adopted, after extensive consultations, by the Canadian and U.S. regulatory agencies, have survived a Canadian court challenge, and began to be given effect in the spring of 1999. (Scientific peer review and administrative processes rarely work in synchrony.) In addition to asking Professor Ankney to act as a referee, I offered Dr. Rockwell the opportunity to counter Cooke's claims. It is unorthodox to see an author and a referee collaborating in writing a response to criticisms of the paper that started this controversy. But I believe that it may be useful, to regulators and managers, as well as to scientists, to set out the alternative views. The debate here hinges on biologists' judgments about the merits of different values of key parameters in a population model. Their choices cannot be strictly "objective," because everyone brings different biases with them, depending on their experiences and beliefs. This is why it is necessary to canvass a wide variety of scientists, as well as other "interested parties," before making major decisions. The importance of this particular case is that a major change in regulations - the authorization of spring shooting by nonnative hunters - was reintroduced, after more than 80 years, on the basis of results from a population model that contained some unreliable estimates. Rockwell and Ankney now claim that their revised target number of geese that must be shot in order to end the population increase is well within reach, after the changes in regulations that have already been put in place in the United States, where there has been a resurgence of interest in waterfowl in the last five years, quite apart from the special case of Snow Geese. However, Cooke et al., without commenting on the feasibility of achieving the goal, caution that, because of uncertainties in the best available estimates of population parameters for Snow Geese, the required harvest could still be up to twice as high as the revised numbers now accepted by Rockwell and Ankney. It must be several years before the outcomes of the general and the specific changes in regulations can be assessed with confidence. This is a most unusual case, involving a decision to reduce the size of an animal population, not because of any detrimental effects on human economic interests, but in order to protect an Arctic ecosystem, in which there had hitherto been no wide public interest. Far more often, the concern of conservation agencies and groups, within and outside governments, is to ensure the preservation of threatened species or populations of animals or plants, especially those of which many people happen to have become aware. In that context, the technique called "population viability analysis" has become fashionable in several countries. That approach, like the one dealt with here, asks regulators to make decisions based on the use of population models. What emerges from the papers presented here is that there are considerable risks in making any management decision that relies on a single choice among many possible numerical solutions derived from such models. The decision-making process should always involve careful peer review of recommendations derived from the products of modelling before any important decisions are made. If this collection of papers increases awareness of the need for caution, it will have been useful. Many other considerations in addition to scientific ones are involved in environmental policy making and decision making. Scientists can play their parts by providing the best available information and advice. That will rarely be as complete and reliable as they would wish, but making a "best guess" is much better than remaining aloof because perfection has not been achieved.
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