A new study released which focusses on the scale of Marine Protected Areas (MPAs) needed to protect large mobile marine animals. MPAs, particularly large MPAs, are increasing in number and size around the globe in part to facilitate the conservation of marine megafauna under the assumption that large-scale MPAs better align with vagile life histories; however, this alignment is not well established. Using a global tracking dataset from 36 species across five taxa, chosen to reflect the span of home range size in highly mobile marine megafauna, this study shows most MPAs are too small to encompass complete home ranges of most species. Based on size alone, 40% of existing MPAs could encompass the home ranges of the smallest ranged species, while only < 1% of existing MPAs could encompass those of the largest ranged species.

Efforts to protect and conserve marine megafauna (including whales, dolphins, shark, turtles, and seabirds) often involve the use of MPAs, and the number and size of these are increasing across the globe. Many proponents of MPAs point to their large size as a mechanism for conserving marine megafauna and their habitats. In fact, many MPAs have been designated because of the megafauna protection they are thought to deliver. But how much do we know about the use of MPAs by megafauna and the extent to which they are contributing to the conservation of these species, many of which often cover vast distances?

This study uses a dataset from 36 species: alongside species like Blue Whale, Basking Shark, Leatherback Sea Turtle, and Crabeater Seal, are a suite of bird species, including Northern Gannet, Gentoo Penguin and Black-footed Albatross. The team examined the degree to which the home ranges overlapped with the existing MPA network (those MPAs that were ‘designated’ or ‘implemented’ in the Atlas of Marine Protection database.

The results reveal, where home ranges and MPAs overlapped in real geographic space, MPAs encompassed < 8% of core areas used by all species. It could be argued that this is unsurprising given the vast ranges used by some of the species studied; the ranges used by Black-footed Albatross and Blue Whale, for example, each cover more than a million square kilometres.

Despite most species’ ranges being much larger than existing MPAs, the study does demonstrate that benefits from MPAs are still likely to accrue when they protect those parts of the range essential to critical life history stages (such as spawning/breeding sites). It is important, therefore, to make sure that MPAs are properly sized, placed and networked, so that they deliver for the species they are intended to protect. As this study shows, tracking data can provide the evidence upon which more robust decisions about MPAs can be made.

The news releases from the British Trust for Ornithology can be read here and from the British Antarctic Survey here. A Q&A with the lead author can be read here. The peer-reviewed journal article can be read here.

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