Saving Sharks with Marine Parks
23 January 2020
The majority of the world’s Marine Protected Areas (MPAs), which cover a median area of 3.3 km2, are between 3 – 15 times too small to help ensure the long-term conservation of coral reef sharks. This discovery, published in Current Biology, demonstrates an urgent need for large fishery closures (> 50 km wide) to protect coral reef sharks.
Unlike migratory pelagic sharks that occupy vast areas of the ocean, the highly resident behaviour and a high dependence upon coral reef habitat is thought to make reef-associated shark species such as whitetip reef, blacktip reef, grey reef, Caribbean reef, and nurse sharks good candidates for conservation using MPAs. However it is currently not known how large these areas need to be to protect species and achieve conservation goals.
Combining movements from individual sharks tracked in the Atlantic, Pacific and Indian Oceans, with 8000 hours of underwater surveys, Ross Dwyer and colleagues determine the effective MPA sizes to protect the five predominant species of coral reef sharks from fisheries-related mortality. A total of 459 sharks (5 species) were tracked using a global network of acoustic receivers, and local shark abundances were monitored in 36 countries as part of Global FinPrint https://globalfinprint.org - a global effort to monitor shark abundances in coral reef habitats.
The authors suggest that while MPAs can be an effective conservation measure to protect reef sharks, the effective size will vary depending on the movements of the target species as well as habitat characteristics and local abundances. For example, MPAs targeting Atlantic Ocean species of reef sharks should be 2.6x larger than Pacific MPAs to protect similar abundances. Our findings support previous concerns about the conservation benefits of MPAs to mobile species and demonstrate that by failing to consider animal movements and lifetime exposure to fishing mortality, the presumed benefits of MPAs to sharks may be overestimated.
Published article available DOI: 10.1016/j.cub.2019.12.005