“Wilderness” might bring to mind sprawling forests in national parks like Yosemite and Yellowstone, but there is a second wilderness—the world’s seas. Now, for the first time, researchers have systematically mapped out that wilderness (in blue, above) by identifying what fraction of the ocean remains largely unaffected by humans. Their answer? Just 13%.
To produce the map, the team didn’t conduct on-the-sea-floor surveys, but instead investigated the regional impacts of 15 human-caused ecosystem stressors, including pollution, fishing, and commercial shipping, all of which have been shown to degrade habitats by disrupting food chains and reducing biodiversity. Areas that were the least affected by all 15 stressors qualified as wilderness. When the numbers were in, just 13% of the ocean—or 54 million square kilometers—met that definition, the researchers report today in Current Biology.
These relatively pristine areas are generally found in remote regions at high latitudes—places where relatively little fishing and shipping occur. There are also some patches near the coasts of New Zealand, Australia, and Chile, likely thanks to low human populations there. But coastlines within the exclusive economic zones of most countries (in red, above)—and heavily trafficked regions like the Atlantic Ocean and northern Pacific Ocean—have next to no marine wilderness left.
Protecting these regions, which are often hot spots of biodiversity, will take a concerted international effort, the researchers say, as less than 5% of marine wilderness now falls within special zones of conservation and management (green, above). And because humans are literally pushing deeper into the sea with deep-sea fishing and oil and gas wells, conservation efforts must extend beyond the water’s surface all the way down to the sea floor. But, the team argues, to preserve something “irreplaceable,” the effort will be well worth it.