Underwater Refuge

Efforts are under way to greatly expand coastal no-fishing zones

Sanctuary. One definition, according to Merriam Webster’s Collegiate Dictionary, is “a refuge for wildlife where predators are controlled and hunting is illegal.”

You’d think, therefore, that the United States’ 13 national marine sanctuaries—more than 18,000 square nautical miles of underwater real estate along U.S. coasts—should be safe havens for their denizens. In fact, most are anything but.

Corals and other slow-growing seafloor inhabitants are especially vulnerable to human impacts, from pollution to run-ins with boats and their gear. Ogden / FIO

The goal of reserves is to protect all marine life, even that not economically exploitable, such as this starfish and sea slug. Kathy deWet-Oleson

Most protected marine areas include some land and adjacent coastal waters, as here at California’s San Miguel Island. Kathy deWet-Oleson

Many fish, such as these fusiliers, depend on complex seabed structures for safety and prey. Ogden / FIO

All the sanctuaries allow fishing. Most also permit recreational boating, mining of some resources, and a host of other potentially disruptive activities.

That’s why calling these regions sanctuaries “is a crock,” argues John C. Ogden, director of the Florida Institute of Oceanography in St. Petersburg. The misnomer confuses the public about how well sensitive ecosystems and beleaguered fish are being protected, he contends.

Ogden’s assertions are borne out by a national survey commissioned by SeaWeb, a marine-environment advocacy group in Washington, D.C. Of 1,000 U.S. adults polled in February, 31 percent guessed that more than one-fifth of U.S. coastal waters are fully protected from fishing and other activities, notes Vikki Spruill, the group’s executive director.

In fact, Ogden notes, only in pockets of some sanctuaries does the federal government prohibit fishing and certain other exploitative activities, such as ship salvaging. He estimates that perhaps only 125 square nautical miles of U.S. marine waters are such “no-take” refuges. The newest and biggest is the month-old 74-square-nautical-mile Tortugas refuge within the Florida Keys National Marine Sanctuary.

Jane Lubchenco of Oregon State University in Corvallis notes that the U.S. tally leaves out many additional no-take areas protected by state or local authorities.

Even including these, however, the total would still come to less than 0.01 percent of U.S. coastal waters, she says.

The nation’s territorial waters extend 200 nautical miles out from all coasts, encompassing a whopping 3.36 million square nautical miles. This so-called Exclusive Economic Zone (EEZ) is an area considerably larger than the nation’s land mass, notes Elliott A. Norse, president of the Marine Conservation Biology Institute in Redmond, Wash.

At a minimum, Norse argues, 20 percent of waters within the EEZ—or some 660,000 square nautical miles—should be set aside within the next 15 years as no-take refuges. Such action is necessary to allow recovery of heavily overfished stocks (SN: 2/7/96, p. 367) and to preserve seafloor communities or rebuild ones that have been wiped out by trawling (SN: 12/19&26/98, p. 388).

Some sensitive old-growth habitats may need a century to mature, Lubchenco says. She would like to see 35 to 50 percent of the EEZ set aside. Yet U.S. industries that exploit the ocean’s resources, especially its fish, have fought virtually every effort to create new refuges. These actions may have been shortsighted, new analyses indicate, because safe havens appear to boost populations of fish outside their borders.

At an American Association for the Advancement of Science symposium in San Francisco in February, Lubchenco and others reported huge benefits to areas in and around no-take refuges. Marine biologists refer to such refuges as marine reserves.

“This was really the first time that the scientific community assessed in depth what the science is telling us about marine reserves,” says Roger Griffis of the National Oceanic and Atmospheric Administration in Washington, D.C. The new findings “show [reserves] have powerful impacts,” he says.

The new analyses appear so compelling, both he and Lubchenco note, that the need for more refuges is at last starting to win grudging support—even among some fishing-boat captains.

Overfishing threat
The United States created its marine-sanctuaries program in 1972, when oil spills and treasure plundering seemed to pose the greatest threat to sea resources. Sanctuaries therefore prohibited oil drilling and salvaging but little else.

Since then, overfishing has emerged as a far bigger threat than oil pollution.

Commercial ships have compensated for dwindling fish stocks by spending more time at work. As prized stocks such as cod and haddock crashed in coastal areas, some to the brink of extinction, fleets began targeting species previously discarded as junk, such as dogfish and angler fish.

Biologists have petitioned governments to put the critical spawning grounds and nurseries of valued species off limits. The fishing industry has countered that this could bankrupt many of its members.

In hopes of averting stalemate, Lubchenco and several colleagues in 1998 recruited a group of experts to launch a new program at the National Center for Ecological Analysis and Synthesis (NCEAS) in Santa Barbara, Calif. During the past 30 months, the group has pored over almost 100 studies of marine reserves, looking for specifics on how well their no-take policies protect ecosystems or let fish stocks rebuild.

By pooling data from many small studies around the world, the scientists were able to tease out some strong generalizations. They found, for instance, that reserves generate benefits quickly.

Densities of surveyed species were, on average, twice as high inside reserves as outside, Robert Warner of the University of California, Santa Barbara reported at the San Francisco meeting. The biomass, or weight of organisms within a reserve, was typically three times that found in an equal-size fished area outside the reserve. Moreover, animals were on average 30 percent bigger inside reserves and the overall species diversity about 20 percent higher, compared with populations outside reserve boundaries.

Some reserves date back to the mid-1970s. Warner’s team discovered that substantial benefits typically show up within just 3 years of a reserve being established and endure for decades. “All reserves, large and small, showed this response,” he noted.

These data also suggest that a system of small reserves may achieve  nefits equal to or greater than a single, large one, Warner says.

Home bodies
The necessary size for a reserve to flourish and to replenish the area around it depends on the flora and fauna present. Until recently, biologists assumed that reserves have to be fairly large to protect the many animal species that flow in and out with the currents and tides.

However, the NCEAS analyses, which are all due to be published this fall as a special issue of Ecological Applications, uncovered another surprise: Many species tend to be home bodies.

The young of most marine animals spend some of their development time as minute larvae—plankton that drift with ocean currents. Depending on the species, this planktonic stage can last anywhere from a few hours to months. The distance larvae float during this time can also vary dramatically—from 3 feet to 550 nautical miles, notes Louis W. Botsford of the University of California, Davis.

In animals with a long planktonic period, larvae hatched in a reserve risk floating beyond their protected home. To ensure that enough of any species with a long larval stage remains in its refuge—creating a self-sustaining population—a reserve’s diameter should be at least as great as the distance that larvae float.

However, where a reserve’s primary goal is to breed abundant fish populations that will migrate beyond the reserve’s boundaries, that diameter shouldn’t be much bigger than this critical size. A series of small reserves would provide a greater total border zone to fishers than one large no-take zone.

Though initial data on planktonic periods suggested that most reserves might need to be hundreds or thousands of kilometers in diameter, the NCEAS analyses may now explain why even many tiny no-take zones seem to build large fish stocks: Their plankton don’t wander far.

For instance, Indonesia’s manta shrimp should be able to travel thousands of kilometers per generation, given that the animal’s larvae drift for about 4 weeks in currents flowing at up to 1 meter per second. At the San Francisco meeting, Stephen R. Palumbi of Harvard University reported, however, that most of the shrimp move only 10 to 30 nautical miles in a single generation. He and his colleagues tracked the movement of eight major populations of the animals by measuring the spread of genes among them.

“And this is not an isolated example,” Palumbi says. He notes that various other marine species in Australia and along the northeast U.S. coast have been spreading at rates representing only a small fraction of what their planktonic periods suggest should be likely.

Indeed, Palumbi and others now advocate the development of national networks of no-take zones—in effect, archipelagos of underwater safe havens. The NCEAS scientists’ computer modeling suggests that networks of irregularly sized and spaced reserves could sustain a wide variety of species, including animals that begin life as long-distance drifters.

However, cautions Steven D. Gaines, director of the Marine Science Institute at the University of California, Santa Barbara, redundancy will be needed within such networks to offset the effects of occasional catastrophes, such as hurricanes, oil spills, and algal blooms. His analysis suggests that planners should increase the area to be preserved by 10 to 100 percent to account for catastrophes, depending on their historical frequency in a region.

Fishing prohibitions
To date, wherever environmental activists and researchers have proposed reserves, fishers have resisted them—and “almost always vigorously,” says Callum M. Roberts of York University in England. However, he adds, evidence “from around the world indicates that fishers have nothing to fear.”

By way of example, he points to data that he collected at the Soufriere Marine Management Area, a coral-reef park off the Caribbean island of St. Lucia.

Daily patrols by park staff have enforced a fishing prohibition in four no-take zones since 1995. Within 3 years, he reports, the density of commercially important fish stocks inside the protected areas swelled and spilled over to areas just outside the park.

The commercial stocks doubled within the area outside the reserves. “Fishers now agree they are better off with the [reserves] than without,” he says.

To probe the long-term impacts of no-take refuges, biologists have been monitoring one of the world’s first: New Zealand’s 1.5-square-nautical-mile Cape Rodney-Okakari Point Reserve off Auckland. Established in 1975, its density of prized fish like snapper (Pagrus auratus) is now 40 times higher inside the reserve than in similar fished areas, Roberts notes. The biomass of spiny lobsters in the reserve has also increased phenomenally—by 5 to 11 percent annually.

Roberts says people quickly learned the advantage of fishing just outside the border of this reserve, and boats line up there daily.

This reserve’s impressive benefits have “paved the way for a national network of marine reserves that is now being built in New Zealand,” Roberts observes. Heather Leslie at Oregon State, who has been studying this network, says that as of last September, New Zealand already had 16 fully protected reserves. Together, they encompass some 2,900 square nautical miles, or nearly 0.2 percent of that country’s territorial waters.

U.S. planners are now investigating how best to begin building such networks of reserves here.

For instance, Leslie has adapted an experimental computer program to combine topographic maps of a region with plots of such features as spawning grounds, fish habitat, fisheries, coral reefs, and fragile seafloor biota. The program can generate a host of possible reserve-network configurations for analysis by local stakeholders—from biologists and oceanographers to scuba divers and squid-fishing fleets.

Leslie recently used the program to suggest hundreds of possible networks of reserves that the government might establish within the 1,252-square-nautical-mile Channel Islands National Marine Sanctuary off California. Currently, only one 0.03-square-nautical-mile reserve exists there.

A local stakeholders group commissioned Leslie and other scientific and economic advisors to suggest how much new territory should be designated no-take. The scientists recently recommended that from 30 to 50 percent of the sanctuary should be in reserves. Now, the stakeholders are studying maps of possible set-asides totaling between 8 and 50 percent of the sanctuary.

Some fishers have begun saying that the maps of proposed reserves have allayed some of their initial fears of a Channel Islands refuge network, observes Lubchenco. The experimental computer program, she argues, “is proving a powerful tool.”

Protected areas
Under an executive order issued last May—which remains in force under President Bush—President Clinton authorized federal agencies “to strengthen the management, protection, and conservation of existing marine protected areas (MPAs) and establish new or expanded MPAs.” These sites include marine sanctuaries and all other fully or partially protected parcels of underwater real estate.

MPAs can range from tidal beaches that are off-limits to visitors during sea turtle nesting periods to areas that ban fishing that disturbs the seafloor. Some MPAs prohibit disturbance of coral or forbid the anchoring of ships; others bar the extraction of sand. One, in Hawaii, outlaws any activities that might disturb young humpback whales.

No existing catalog identifies all U.S. MPAs, let alone the subset that has been granted reserve status, Griffis notes. His office is developing such a registry and will post it on a Web site for use by individuals and government agencies seeking to nominate new MPAs.

Griffis’ goal is to have by year’s end a list of all MPAs, cross-indexed by location, ecosystem, and level of protection. Knowing what’s already out there is an essential first step to building coordinated networks of marine reserves, he says.

However, Lubchenco points out, even reserves can’t prevent toxic or nutrient pollution, alien-species invasions, or climate change. Overfishing of top predators in areas outside reserves also can affect populations within no-take areas. That’s why, she warns, although “networks of marine reserves may be the single most useful tool at our disposal,” they will never, by themselves, be sufficient to protect the increasingly imperiled seas.

Janet Raloff

Janet Raloff is the editor of Science News for Students, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer.

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