September 24, 2014 — 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.
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.
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