The management of hunting of Anatidae

The objectives of harvest management for members of family Anatidae typically involve the size of the harvested population and the size of the harvest. Hunting regulations are the primary tool used to try to achieve the objectives of harvest management. Informed harvest management thus requires a knowledge of the relationship between hunting regulations and both Anatid abundance and harvest. Results of retrospective studies in North America provide evidence that generally restrictive regulations produce lower harvest rates than generally liberal regulations. However, such studies have provided little evidence that specific hunting regulations designed to produce a change in the relative harvest rates of different species, or of the sexes within a species, have been successful in 'directing' harvest toward specific groups of birds and away from other groups. Estimates of the strength of the relationship between harvest mortality rates and annual survival rates of Anatidae have ranged from weak to strong. Thus, the key relationships for harvest management of Anatidae, those between hunting regulations and the size of both the subsequent harvest and the subsequent population, are not 'known' but are characterized by uncertainty. In the United States, this uncertainty led to a risk-aversive conservatism that characterized the setting of hunting regulations during the last decade. Recently, managers have begun to consider using hunting regulations themselves as a means to better understand the system being managed. This approach, referred to as active adaptive management, attempts to balance short-term demands for hunting opportunity with the learning needed to improve long-term management performance. Learning is accomplished by periodically comparing observed system response, as estimated by ongoing survey and data collection programs, with predictions of competing models. These periodic comparisons lead to changes in measures of credibility associated with the different models and thus to a reduction in uncertainty. We suggest that this approach might be useful in other countries that have implemented requisite data collection programs for their Anatid populations.