Scientific advice on species at risk: a comparative analysis of status assessments of polar bear, Ursus maritimus

The assessment of species believed to be at heightened risk of extinction must be underpinned by scientific evaluations of past and predicted changes in abundance and distribution. When these assessments are communicated to society and (or) government, they provide an informed scientific basis for public policy decisions pertaining to the protection of biodiversity. The provision of advice for high-profile species can be particularly challenging as different interest groups may seek to over- or under-play a species' degree of endangerment. Those challenges are highlighted here by a comparative analysis of assessments of polar bear (Ursus maritimus) undertaken recently in Canada, the United States, and by the World Conservation Union (IUCN). Perceived differences in these assessments can be partly attributable to differences in the species status categories used by different organizations, the nature and application of assessment criteria, and the legislative responsibilities of those undertaking the assessments. Our analysis also highlights differences in how status assessments have informed the scientific basis for discordant projections of the future magnitude of polar bear habitat and population change. We conclude that evaluations of the scientific merits associated with any species status are hindered by imperfect understanding of differences in assessment protocols. Scientific advice potentially informed, but ultimately undermined, by personal and institutional biases serves neither decision-makers nor society well.