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A yellowmargin triggerfish patrols Palmyra Atoll, part of the expanded marine monument.

A yellowmargin triggerfish patrols Palmyra Atoll, part of the expanded marine monument.

Laura M. Beauregard/USFWS

Will 'lazy' fish benefit most from new U.S. marine megareserve?

President Barack Obama has moved forward with a plan to vastly expand three remote U.S. reserves in the central Pacific Ocean into a massive national monument.

In June, White House officials announced that they were considering expanding the Pacific Remote Islands Marine National Monument (PRIMNM), which covers about 225,000 square kilometers. On Wednesday evening, the White House announced that Obama will sign a proclamation expanding the monument to about 1.27 million square kilometers. Obama is acting under authority granted by the Antiquities Act, which allows a president to create a national monument with the stroke of a pen, and without action by Congress.

The total is somewhat smaller than a proposal to protect some 1.8 million square kilometers that the White House floated in June. Obama will extend fishing bans and other monument protections to include the entire U.S. exclusive economic zone around the islands of Jarvis, Johnson, and Wake (the zone extends to up to 200 nautical miles offshore). But the White House did not advance plans to greatly expand protections around the islands of Palmyra, Howland, and Baker, which are targeted by tuna fishing boats. Making that move would have allowed the new U.S. monument to bump up against another megareserve, the Phoenix Islands Protected Area, and create the world's largest swath of ocean closed to fishing. Fishing groups had opposed closing the tuna fishing areas, saying it would have created economic hardship.

Still, conservation groups are applauding the move. “This marks an important day for ocean conservation in this country,” said Matt Rand, the leader of the Pew Charitable Trust’s Global Ocean Legacy project, which has advocated for the expansion, in a statement. “We hope the steps taken today by the U.S. government will accelerate similar actions by a growing list of coastal nations to protect more of the world’s great ocean treasures.”

Marine researchers predict the move will benefit a vast array of marine creatures by helping protect relatively remote and intact ecosystems. But they note any benefits could be decades away for some of the region’s most heavily exploited fish, including certain species of tuna. And how fast those populations recover could depend partly on just how “lazy” some of the fish are.

In general, relatively little fishing occurs in the remote waters covered by the new reserve. Few fishing boats ply the waters around the atolls of Wake and Johnston, east of Hawaii, where fish abundance is naturally low. A fleet does target the more tuna-rich waters around the islands of Howland, Baker, Palmyra, Kingman Reef, and Jarvis. But those areas produce less than 4% of their total catch (mostly bigeye and skipjack tuna), according to figures from the National Oceanic and Atmospheric Administration (NOAA).

Tuna species that don’t stray far from the reserve during their lives could see quick benefits. For example, recent studies suggest that more than 90% of yellowfin tuna found around the main Hawaiian Islands remain in the region. (Yellowfin populations are estimated to be at 38% of historic levels.)

The reserve’s immediate impact could be more muted, however, for fish species that routinely travel vast distances, and so spend relatively little time in the new preserve, biologists say. In particular, recent tagging studies suggest that bigeye tuna—prized for sushi and down to just 16% of historic populations—“do not exhibit any prolonged residency in this or any other area of the equatorial central Pacific,” wrote John Hampton, director of the Oceanic Fisheries Programme at the Secretariat of the Pacific Community in Nouméa, in an e-mail. (The group advises Pacific states on how to fish sustainably.)

Even within mobile species, however, the reserve could help, researchers say. That’s because fish are like people: Some like to travel, and others are homebodies. For bigeye tuna, the proportion of lazy fish is unknown, but “the point is that some will [stay within the reserve, and] they will produce more offspring during a longer life than those who don’t,” says fisheries scientist Daniel Pauly of the University of British Columbia, Vancouver. The lazy fish may also “pass on their short-travel habits to their offspring, who will grow in numbers.”

Indeed, over many years, modeling studies suggest the reserve could even encourage the evolution of “lazier” but healthier fish populations, says fish geneticist Jon Mee, a former colleague of Pauly’s who is now a postdoctoral fellow at the University of Calgary in Canada. “We have lots of evidence that mobility has a genetic basis and is inherited to a fairly high degree,” he says. And if fish “that move more, die more, you will get evolution.” In simulations that Mee is developing, lazy individuals living in protected areas can have higher reproduction rates than their more mobile—and more vulnerable—relatives, leading to larger but less mobile populations.

Another long-term benefit provided by the new reserve could be to make fish populations less vulnerable to climate change, says Patrick Lehodey, an oceanographer at the French satellite company CLS in Toulouse, France. In a recent study published in Climatic Change, he and colleagues found that by 2060, waters in the Central Pacific, where the reserves are located, will become warm enough to attract more skipjack tuna from the Western Pacific, where populations are now usually denser and fishing is more intense.

Such results suggest there are few downsides to expanding marine reserves, says Jane Lubchenco, a marine ecologist at Oregon State University and NOAA administrator from 2009 to 2013.  “It makes sense to protect an area before it’s seriously degraded,” she says.

See here for more on conservation science.

*Update, 25 September, 7:30 a.m.: This story has been updated to clarify how the final White House plan differs from the proposal presented in June.

*Update, 25 September, 11:46 a.m.: The lead has been corrected; the new additions will fall short of doubling the total area of the world's marine reserves. The details of the expansion have been clarified. Jane Lubchenco's quote has also been updated.