Seeking a rational approach to setting conservation priorities for marine mammals

The U.S. Endangered Species Act establishes categories for endangered and threatened species but provides no criteria for deciding when a species should be listed, delisted, or downlisted. As a result, listing and recovery actions for marine mammals are widely inconsistent. In most cases, Endangered Species Act listing and recovery actions have been done without the benefit of high-quality population assessments and have been based on arbitrary, nonquantitative criteria. A new approach to determining classification criteria for marine mammals is presented, with the North Pacific humpback whale as a test case. The key idea underlying this approach is an attempt to incorporate biological uncertainty explicitly in the definition of threatened and endangered. I sketch the essential ingredients of this new approach and its motivation and use this discussion to illuminate the challenges we face in pursuing conservation in an uncertain and data-poor world.