Global evaluation of shark sanctuaries

Due to well-documented declines in many shark populations there is increasing pressure to implement new management and rebuilding strategies at the national and international scale. Since 2009, fifteen coastal countries in the Atlantic, Indian and Pacific Oceans have opted to ban commercial shark fishing altogether, and have laws that prohibit the possession, trade or sale of sharks and shark products. These 'shark sanctuaries' collectively cover > 3% of the world's oceans, a similar coverage as all currently established marine protected areas combined. Despite their prominence, and an intense scientific debate about their usefulness, the condition of shark sanctuaries has not yet been empirically evaluated. Here, we report results from a global diver survey used to set baselines of shark populations, human use patterns, public awareness and threats in all 15 shark sanctuaries, and contrasted with observations from 23 non-sanctuary countries. Specific results varied by country, but there were some general trends: i) shark sanctuaries showed less pronounced shark population declines, fewer observations of sharks being sold on markets, and lower overall fishing threats compared to non shark sanctuaries, ii) bycatch, ghost gear, marine debris and habitat destruction are significant threats that are often not addressed by sanctuary regulations and need to be resolved in other ways, and iii) participants in sanctuaries were more optimistic about the survival of shark populations in local waters, but also highlighted the need for further conservation efforts. These results suggest that shark sanctuaries, as seen through the lens of local experts, may be a helpful conservation tool but likely not sufficient in isolation. There is an urgent need for higher-resolution data on shark abundance, incidental catch, and markets to direct priority conservation needs and optimize the conservation benefits of existing and future shark sanctuaries.