Has designating and protecting critical habitat had an impact on endangered North Atlantic right whale ship strike mortality?

Ship strike is the major anthropogenic source of mortality for severely endangered North Atlantic right whales. Two primary tools are given to US wildlife managers by the Endangered Species Act post-listing to ensure species survival by reducing negative anthropogenic impacts: (1) creating a recovery plan and (2) defining and protecting critical habitat. This study reviews and analyzes the impact these strategies have had in reducing North Atlantic right whale ship strike mortality in US waters from 1973 to 2011. Defining and protecting critical habitat poses distinct spatial and human-use overlap challenges when applied to highly migratory species. Managers should consider two different levels in designating critical habitat for highly migratory species such as the North Atlantic right whale: permanently protected critical habitat in areas where species take up seasonal residence, and temporarily protected migratory habitat to maintain functional migration corridors between seasonal residence critical habitat areas. Managers and stakeholders should also be aware that, given current definitions for North Atlantic right whale critical habitat, human-use overlap in critical habitat areas is inevitable. Instead of eliminating human-use in critical habitat, wildlife managers should apply a combination of adaptive human-behaviors, functional habitat definitions, and on-going habitat-use studies to reduce ship strike mortality, particularly for pregnant and nursing females. Ascertaining methods to effectively manage North Atlantic right whale critical habitat is particularly relevant as current regulatory actions aimed at reducing North Atlantic right whale ship strike mortality will be reviewed by the National Oceanic and Atmospheric Administration in December 2013, offering wildlife managers an opportunity to adjust current ship strike mortality reduction strategies in order to improve the population growth rate.