There is really only one ocean. But over time, it's been cordoned off into various regions, with the most fluid of boundaries. Today, geographers recognize more than 50 seas within five major oceans. There are also more than 150 Exclusive Economic Zones where individual coastal nations exercise sovereignty up to 200 nautical miles from their shores.
Now, thanks to the rise of marine protected areas (MPAs), the global ocean is becoming increasingly partitioned. The term is a catchall for sites like ocean sanctuaries, marine parks, and no-fishing zones—scattered havens where marine life is supposed to thrive, free of human interference (or, at least, subject to limited human interference). The world's 5,000-plus MPAs include national treasures like the Galápagos and the Great Barrier Reef, but they also include small "fishery-management zones" that are undistinguished except for fine-print prohibitions on certain types of fishing gear. Even the Great Barrier Reef is open to extractive activities like trawl fishing and deep-sea dredging.
Only 2 percent of the ocean is currently covered by some sort of MPA. (In contrast, 12 percent of the world's land is protected in national-park systems and wildlife preserves.) And only half of that 2 percent—a mere 1 percent of the ocean—is classified as "no-take," or completely closed to fishing and other extractive activity.
The international conservation community has long heralded the role of MPAs in protecting ocean resources. But amid growing concern over how to save the seas from overfishing, acidification, and "dead zones," ecologists and economists are beginning to ask a fundamental question: Are these special conservation zones actually achieving anything?
Such queries are especially important in light of news that Palau, a small island nation in Micronesia, intends to turn its entire territory into one giant marine reserve. Commercial fishing would be banned from Palau's coasts to the outer reaches of its Exclusive Economic Zone—in sum, an area of about 230,000 square miles. Palau, it seems, has decided that attracting more tourists and scuba divers is worth shunning the commercial fishing industry.
In March, two economists at Columbia University put some numbers to the upside of MPAs, arguing in a paper for the National Bureau of Economic Research that these zones are only worthwhile if they make up at least 8.5 percent of a country's Exclusive Economic Zone. That's the tipping point at which the costs of implementing MPAs are outweighed by the benefits they confer through boosts to the country's tourism and fishing industries.
But thinking about conservation only in terms of percentage of area covered may not be the best strategy. In February, the marine geographer Rodolphe Devillers and other researchers published a study asserting that the majority of MPAs are "residual"—established in locations of convenience rather than in places where they could actually do good. Creating a "no-take" marine reserve sounds like a significant action, unless you choose to locate it in a corner of the ocean where no one wants to fish or drill, and where there are few species in need of protection.
According to Devillers and his co-authors, this is a consequence of politics, industry influence, and the widely accepted use of "area size" as a measure of success. When governments like Australia's try to enact MPAs in a way that pleases everyone, their goals are are to minimize costs, avoid conflict with commercial interests, and still be able to boast about protecting "x" square miles of habitat. A Case in point: In early April, the Australian government "created Australia’s largest fully protected marine reserve near two far-flung islands, in a move which environmental groups say will help safeguard rare whale species." As The Guardian reported:
The reserve now spans 71,200 sq km of ocean. Heard and McDonald Islands, an Australian external territory located 4,100 km south-west of Perth, are barren, uninhabited outposts considered among the most remote places on Earth.
All this isn't to say that the Heard and McDonald Islands are devoid of natural resources. In fact, according to the MPAtlas database, the territory serves as an important breeding habitat for seabirds and seals, and the surrounding waters act as a "nursery" for commercially harvested fish species. It's just that the biggest threat these barren, uninhabited Antarctic islands appear to be facing isn't exploitation by commercial fishermen or oil companies, but rather climate change. And that's not something a marine reserve can protect against.