Implications of uncertainty for Canada’s commercial hunt of harp seals (Pagophilus groenlandicus)

• Published in: Nature Precedings
• Main Authors: Leaper, Russell, Matthews, Justin
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2008
• Subjects: Psychiatry and Mental health; Canada; Tac; Harp Seal; Pagophilus groenlandicus
• Online Access: http://dx.doi.org/10.1038/npre.2008.1798.1; http://www.nature.com/articles/npre.2008.1798.1.pdf; http://www.nature.com/articles/npre.2008.1798.1

Abstract The Canadian government's current management procedure for harp seals is described by Fisheries and Oceans Canada as using the Precautionary Approach. Employing a similar underlying population model, we simulated the effects of uncertainty involving bias in estimates of human induced mortality, natural mortality, and pup production estimates as a set of robustness trials. Our results indicated that for the range of annual total allowable catches (TAC) considered and set for Canada’s commercial harp seal hunt (250,000 – 350,000), there were plausible circumstances under which the government's management procedures failed to meet their own conservation objectives. By contrast, a precautionary management regime should be robust to such levels of uncertainty. For some scenarios the current management strategy, although not fully specified, is likely to maintain a high TAC despite a declining population. In particular, once a high TAC has been set, the assessments are unlikely to provide the necessary evidence that the TAC should be reduced until the population is at a low level. Hence there is a substantial risk that the population may be depleted below the ‘minimum’ (N50) and ‘critical’ (N30) population reference points. There is a need for a management procedure based on risk analysis to be fully specified and tested. In the interim, reducing TACs to within limits calculated from a well-established precautionary procedure, such as Potential Biological Removal, would be a step towards more precautionary management.