Needed: Underwater ‘national parks’
Set-asides can restore ocean balance and diversity – but all stakeholders must buy into them.
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MPAs have other, less-direct effects. In California’s Channel Islands, for example, lobsters have grown in size and abundance since closure. Bigger lobsters eat more sea urchins. Sea urchins eat kelp, so fewer urchins means more kelp. The end result of more lobsters is a healthier kelp forest, which provides more habitat for seaweed-loving fish like kelp bass.
Increased biodiversity is another gain. Like diverse stock portfolios, biologically diverse ecosystems tend to fail less often than simpler ones. They’re more resilient to disease and extreme weather.
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Intact ecosystems are thus more likely to survive the predicted disturbances of human-induced climate change. And for fisheries biologists, closed areas serve as a reference, a way to determine what percentage of observed changes are due to local human impacts versus natural variation or global climate change.
“Climate change is going to affect inside and outside, but now you can actually use [MPAs] to decouple the relative effects of climate change from the effects of fishing,” says Mark Carr, a professor of marine ecology at the University of California, Santa Cruz, and science adviser to California’s MLPA Initiative.
Confronted with the prospect of losing fishing grounds, fishermen often assume they’ll lose income, too. But Chris Costello, an associate professor of resource economics at the University of California, Santa Barbara, says MPAs’ economic impact depends on placement. If they are placed wisely (closing remote areas that are costly to fish, anyway, rather than heavily fished ones that are closer), economic losses can be minimized. In closing some 20 percent of California’s north central coast, for example, he estimates only a 6 percent loss to fishermen. Modeling indicates that if MPAs are placed in alignment with ocean currents, they can continually flood adjacent areas with larvae, having a net positive effect on nearby fisheries.
“This is not intuitive to policymakers or fishermen,” Dr. Costello says. But “at least in theory, you can have your cake and eat it, too.”
Scientists conceived California’s MPAs as a network. Each area has to be larger than the distances that target organisms wander, 6 to 12-1/2 miles along the coastline and extending three miles out to sea. They have to be spaced close enough (no more than 62 miles apart) so that larvae from one MPA can drift and settle into another. Designed with the greater whole in mind, in theory the network’s benefit will be greater than the sum of its parts.
Not everyone agrees with all the assumptions guiding the process.
Ray Hilborn, a professor at the University of Washington’s School of Fishery and Aquatic Sciences in Seattle, and a science adviser to the north central coast process, thinks the presumed benefits to fisheries are questionable. The MPAs are only large enough to protect the least mobile of species, which leaves out commercially important ones like hake, squid, and sardines – open-water species that swim hundreds of miles during feeding and spawning cycles.
Also, he says, traditional management schemes are working fine in California waters. (Many fault poor oceanographic conditions and water use in the Sacramento River, not overfishing, for this year’s dramatic West Coast Chinook salmon collapse.)
“The MLPA was basically sold on the … ‘ecosystem is in trouble’ perspective,” he says. “And I think that’s a serious exaggeration.” The network should be called what it is, he says: a biodiversity tool.
Indeed, the Marine Life Protection Act explicitly declares conservation as a primary goal, a fact not lost on either scientists or stakeholders.
“We went in there knowing we were going to have to give up some [fishing] grounds,” says Michael McHenry of Half Moon Bay, Calif., who has fished for nearly 40 years. “We just tried to go in and soften the blow.”