The campaign to protect 30 percent of the world’s oceans by 2030, supported by more than 70 nations, is known mostly for soaring ambition and scant achievement so far. Just 7 percent of the seas are protected and only 2.7 percent are highly protected.
“It is very optimistic to think we’ll reach ‘30 by 30,’” says Patricia Majluf, a Peruvian fisheries scientist who has worked to create a deep-sea protected area off Peru in the face of strong resistance from the fishing industry. Peru has protected less than half a percent of its offshore waters. The proposed Nazca Ridge Marine Protected Area, on an undersea mountain range that stretches out into the Pacific from the Peru coast, is expected to be finalized this spring. It would boost Peru’s protected waters to 8 percent.
Setting aside nearly a third of the oceans, the fishers say, is an idea developing nations in South America and elsewhere can ill afford. That argument against a large expansion of marine protected areas (MPAs) is heard around the world, and the chasm between conservationists and fishing interests has grown wider as fishing stocks decline and the appetite for seafood grows along with the global population.
Research published today in Nature aims to dramatically change that narrative. The study suggests that protecting 30 percent of the oceans not only could restore biodiversity to ocean habitats, it could increase the annual global catch by eight million tons—about 10 percent of the catch today. And, as a bonus, it would provide a “cheap, natural solution” to climate change by reducing the amount of seafloor carbon emitted into the seas by fishing trawlers.
“The only way to get more food from the ocean is to protect more,” says lead author Enric Sala, a marine ecologist and explorer-in-residence at the National Geographic Society, which in part underwrote the study. “The catch has been declining since the mid-1990s and this would provide a benefit forever.”
In the study, an international team of 26 scientists analyzed the world’s unprotected ocean waters to calculate which are threatened by overfishing, habitat destruction, and release of carbon. The team, which included economists and marine and climate scientists, then mapped locations globally where protections would provide the greatest benefits to fish stocks, biodiversity, and climate.
The findings created a framework that the scientists say can be used by nations to address the three related challenges separately or in combination, as their national priorities dictate. Fully addressing all three would require that at least 30 percent of the oceans be protected, they say. But nations could still realize significant protections by focusing on key areas, and global cooperation to strategically locate protected areas could be nearly twice as effective as individual nations working alone, they say.
The research is the first effort to analyze the potential release of carbon dioxide into the oceans as a result of bottom trawling fisheries and dredging for invertebrates such as scallops. Marine sediments are the “largest pool of organic carbon” on Earth and a key reservoir for long-term storage, according to the study.
The carbon released as heavy nets are dragged across the seafloor, stirring up sediment, “could likely increase ocean acidification,” the study says. It could also reduce the capacity of the ocean to absorb CO2 from the air, thus adding to the atmospheric build-up that drives global warming.
Just how much atmospheric CO2 is increased by bottom trawling is unknown, Sala and his colleagues acknowledge. But because the global footprint of trawling is small, they say, protecting just 3.6 percent of the ocean would eliminate 90 percent of the risk. The areas most vulnerable to carbon release are found on the continental shelves and include China’s Exclusive Economic Zone, Europe’s Atlantic coastal areas, and Peru’s Nazca Ridge.
With an eye to an October meeting of the United Nations Convention on Biological Diversity in Kunming, China, the scientists argue for greater global cooperation on marine protection. In Kunming, the UN hopes 190 nations will finalize an agreement on biodiversity with the "30-by-30" plan as a primary tenant.
“That’s one reason we did this,” says Sala, who directs the Pristine Seas Program at the National Geographic Society. “We need to make sure the science is so clear that no political maneuvering will prevail on how much we are going to leave to nature. Right now we are at the law of diminishing returns. The ocean cannot absorb our impacts. It can’t keep up with us. We need to give the ocean more space so it can continue providing for us and the rest of life on the planet.”
The scientists say most of what they call priority locations are found within the Exclusive Economic Zones of coastal nations, the term for areas that extend 200 miles off of coasts. A handful of marine protection areas set up on the high seas—where waters are governed by international law—would also pay large benefits in recovered habitat and fish populations. These include the Mascarene Plateau in the Indian Ocean, the Southwest Indian Ridge between Africa and Antarctica, and a pair of massive underwater mountain ranges—the Mid-Atlantic Ridge and Peru’s Nazca Ridge.
The most productive waters in the world
Protection of the Nazca Ridge, which is an underwater mountain chain formed by volcanic activity, would protect biodiversity in some of the most productive waters on the planet. The Nazca Ridge is habitat for deepwater sharks, serves as nurseries for swordfish and the jack mackerel, and is a migratory stop and breeding ground for blue whales. More than 40 percent of the fish and invertebrates that live on or around the ridge are found nowhere else on earth, and the area chosen for the new marine protected area contains many threatened, endangered, or declining species and habitats that are fragile and slow to recover from human disturbance.
The proposed MPA is nearly 27,000 square miles, or 7.3 percent of Peruvian waters. Majluf, who also serves as a vice president in Peru to Oceana, a conservation nonprofit, says protecting the area would prevent possible damage to the seamounts if the area were opened to fishing for Patagonian toothfish, which is marketed as Chilean sea bass and caught using bottom-set longlines. At present, less than seven percent of the annual toothfish catch is landed within the boundaries of the proposed protected area.
Protecting the ridge would also help keep out of Peruvian waters a Chinese fleet that fishes off South America for squid, says Majluf, who was not involved in the Nature paper.
Should the Nazca Ridge marine protected area be finalized, Peru will have met all but 2 percent of its pledge to protect 10 percent of its waters. Says Majluf: “Our future is little MPAs, closer to shore, and fighting other human activities.”