New threats for leatherbacks

By Paul Koberstein

It's August 2007 and scientists are heading for the beach — but not for a swim. It is just after sunset, and they are patrolling the sand for sea turtles whom they hope will crawl out of the surf and start digging their nests. The location is Jamursba-Medi, Papua, a province of Indonesia on the western half of the island of New Guinea. Jamursba-Medi is the largest leatherback rookery in the entire IndoPacific region and a place that is vitally important to sea turtles who spend a good part of their lives near the West Coast of the Unite States, an area that marine biologists call the “California Current.”

One of the biologists on patrol at the beach is Scott Benson with the National Marine Fisheries Service. He is author of new research that served a critical role in killing a proposed commercial drift gillnet fishery in the California Current, and that may soon help to doom a longline fishery there as well. The gillnet fishery exposes critically imperiled leatherback sea turtles to potential injury or death.

“Each nesting leatherback performs an intricate set of choreographed movements to create a body pit and nest cavity, then she deposits her eggs and disguises the nest,” Benson writes in his blog at http://gtopp.org/. “The hind flippers do the digging and are remarkably dexterous. The entire performance is astonishing, and I've never met anybody that wasn't pleasantly shocked after witnessing it for the first time.”

They find a turtle that has entered a trance and is laying eggs; soon two other females emerge from the surf. Benson's team attaches satellite transmitters, and for permanent identification, inserts Passive Integrated Transponder (PIT) tags the size of a grain of rice under each turtle's leathery skin. Leatherbacks are unique among turtles in that they have no hard shells.

“We stumble back to camp tired, wet, but happy,” Benson writes. “Three more turtles tagged.”

They are some of the largest and longest living reptiles on Earth. “Having outlived the dinosaurs, the leatherback is, in effect, the last survivor of the age of giant reptiles,” says Brenden Cummings, attorney for the Tucson-based Center for Biological Diversity.

DANGERS LURK UP AHEAD, INCLUDING A GAUNTLET OF FISHING LINES

In Indonesia and elsewhere in the western Pacific, there is renewed hope for the leatherbacks. Local communities near Jamursba-Medi no longer harvest leatherback eggs and are working to control feral pigs that like to feast on them as well. But far away in the eastern Pacific, near America’s western shore, new threats are just on the horizon.  

The leatherbacks of Jamursba-Medi like to forage on jellyfish but must travel thousands of miles across the Pacific to find them. Few other reptiles migrate such a great distance for a meal. Their destination is the California Current, home of dense clusters of the bell-shaped invertebrates. The leatherbacks also provide a service to the ecosystem by helping to control jellyfish populations that otherwise grow rapidly in the presence of the abundant supplies of small fish and larvae that live in the California Current.

But to reach the jellyfish they must first swim through commercial longline fishing fleets near Hawai`i, about halfway along their migration route. That route intersects hundreds of thousands of baited hooks dangling dangerously in the water, and their targeted catch, swordfish. Every year worldwide, longliners set as many as 10 billion baited hooks attached to lines that can stretch up to 60 miles long.

In the Pacific, where leatherback populations are much smaller than in the Atlantic, commercial fishing kills thousands of turtles each year. Scientists predict that leatherbacks could become extinct within 10 to 30 years unless there is a significant reduction in adult mortality.

The killing of sea turtles by longline gear is a worldwide problem. According to researchers from Duke University, longline fisheries killed some 50,000 leatherbacks in 2000 alone. The leatherback population declined by 95 percent in the last two decades of the 20th Century, when the World Conservation Union listed it as a “critically endangered species” and the United States listed it as “endangered.”

The turtles do not normally ingest the baited hooks. Most die when the plastic fishing lines wrap around their unusually long flippers. If they cannot get free themselves, or the fishing crew fails to rescue them, they can drown.

The leatherbacks who are hooked by the longlines are labeled “bycatch,” which means the harvest is unintentional and yet can be very significant. Over the years, longline bycatch has decimated the leatherback population.

The National Marine Fisheries Service reacted belatedly to the leatherback collapse by enacting several conservation measures in the early part of this century. In 2001, it banned all swordfish longlining east of the 150th meridian, a line that nearly evenly divides the Pacific. That year, NMFS closed the Hawai`i-based longline fleet after a federal court ruled that too many leatherbacks were being killed by the boats.

In 2004, NMFS also prohibited any longline fishing within the entire exclusive economic zone that stretches out 200 miles off all coasts.

NMFS also created the Pacific Leatherback Conservation Area, a 180,000 square mile area extending from Big Sur, Calif., north to Lincoln City, Ore., and out to 300 miles offshore. The conservation area protects turtles in their jellyfish feeding grounds from longlines or drift gillnets, which are also a danger to sea turtles.

But in 2004 NMFS reopened the Hawai`i fishery after a new kind of hook was introduced that it said was safer for the turtles. Longline boats quickly returned to the fishery.

In April 2007, the federal Pacific Fishery Management Council backed a plan allowing longlining with the improved hook within the turtle conservation zone,

Mark Helvey, an assistant regional administrator the NMFS, the same agency that employs Benson, said the new fishery would be just experimental, just a test to determine whether it would be economical and safe for leatherbacks. Or, at least safer than an alternative way of catching swordfish, the drift gillnet.

But the drift gillnet fishery's excellent record of late will be tough to beat. Seasonal and area closures have reduced the drift gillnet fishery's bycatch of sea turtles to zero since 2001. Helvey said that the protective measures instituted in 2004 reduced sea turtle mortalities by about 90 percent in the Hawai`i longline fishery.  

He predicted the longline fishery would harm only a handful of leatherbacks, perhaps as few as just one. But Karen Steele of the Turtle Island Restoration Network, a Marin County-based organization, said mortality could be higher. Some leatherbacks caught in the longline fishery have been shown to die after they are released by the fishing vessel, but federal statistics have no way of accounting for these deaths.

Only one boat, owned by longtime fishermen Pete Dupuy, would use up to 60-mile-long main lines, with hooks set at an approximately every 40 meters. In all, he would use some 67,000 hooks. His proposal called for four trips from September 15, 2007 through December 2007, but they now have been delayed.  

Dupuy's permit would allow the harvest of up to 18 tons of swordfish, but swordfish would represent only about 40 percent of the total catch. Non-target species, including sea turtles, blue sharks, seabirds and marine mammals, would make up the other 60 percent of the catch. The only currently practiced fishery for swordfish that avoids significant bycatch of any kind is harpoon fishing. Some restaurants specify on their menus that they feature harpoon-caught swordfish.  

But the council's science advisors refused to endorse the new fishery. They said, “no experimental design is proposed to test the hypothesis that longline gear would offer an improvement in bycatch rates over drift gillnet. Data collected from a single vessel” would not be adequate for this purpose. But the council disregarded that piece of advice and approved the plan to allow longlining in the turtle conservation zone, anyway.

Pacific Fishery Management Council votes several times to weaken sea turtle protections.

 

Steele says her organization has consistently opposed longline fishing along the West Coast, and not just due to its impacts on the leatherbacks, but also because of harm to loggerhead sea turtles, marine mammals and sea birds.  “These extensive bans by NMFS, primarily to protect endangered sea turtles, demonstrates the vulnerability of these species to the impacts of longline fishing,” Steele says.  

Cummings of the Center for Biological Diversity said the Bush administration would violate seven environmental laws, including the Endangered Species Act, if it issued the permit to Dupuy. He said banning longlining has strong international support among scientists.   

“Over 1000 international scientists from more than 100 countries and 300 non-governmental organizations from 62 countries (are) calling on the U.N. to institute an immediate moratorium on pelagic longline fishing in the Pacific until measures can be put in place that protect the leatherback,” Cummings said.  

In September 2007, the Center for Biological Diversity, Turtle Island and Oceana petitioned NMFS to provide stronger protection under the Endangered Species for the sea turtle, asking the agency to declare foraging areas off the Oregon and California Coast as the leatherback's “critical habitat.”

The Endangered Species Act defines critical habitat as “areas essential for the conservation of the species.” The Pacific council has voted several times in the last 18 months to weaken protection for the leatherback. It approved a drift gillnet fishery in the leatherback conservation zone — a fishery that would have been even more damaging to protected species than longlining, according to NMFS.  

In the summer of 2007, NMFS rejected the drift gillnet plan. It said Benson's research. spanning over a decade, “documents the importance of near-shore waters off the U. S. West Coast for foraging leatherback turtles.” The Pacific council's votes for these fisheries featured the usual conflicts of interest as council members' own business interests tangled with council business.

Council member Kathy Fosmark, of Carmel, Calif., would have directly benefited from the drift gillnet fishery. Her family owns a drift gillnet boat that would have participated.  Another council member who strongly advocated the experimental fisheries was Rod Moore, the executive director of the West Coast Seafood Processors Association, a trade association whose members could financially benefit from the fisheries. Moore, in fact, made the motions to open both fisheries in the sea turtle protection zone.

 

More support for the fisheries came from Curt Melcher, deputy director of the Oregon Department of Fish and Wildlife. Unlike California and Washington, Oregon has raised no objections to the potential harm they could do to the leatherbacks. State representatives from Washington made sure the longliners came nowhere near Washington waters. California aggressively pursued a challenge to the longline fishery.

The proposal went before the California Coastal Commission, which voted to object after a hearing in August 2007. “Considering the status of this species, even one mortality would represent a significant impact,” the California Coastal Commission said.

The coastal commission has historically urged the fullest possible protection for leatherbacks. “The status of leatherbacks in the Pacific Ocean is so precarious that some scientists believe they will become extinct within one or two human generations,” the commission said.  

Studies by Benson and others serve to reinforce that conclusion. Declines have been documented at nesting beaches in the eastern Pacific and throughout the Indo-Pacific region. Scientists have documented a complete loss of the Malaysian nesting population, severe declines at nesting beaches in Costa Rica and Mexico, and lesser declines at western Pacific nesting beaches, according to Benson's study, published by NMFS in its Fisheries Bulletin in 2007.  

Another report, a review of the leatherback's status, published NMFS and the U. S. Fish and Wildlife Service in August 2007, says the incidental bycatch in commercial fishing operations, including longline fisheries, “is a major impact that is far from being resolved.”   

The status review, published every five years, said the most recent population size estimate for the North Atlantic alone is a range of 34,000-94,000 adult leatherbacks, an increase over earlier estimates.  Satellite telemetry studies described by Benson linked leatherback foraging in the California Current with turtles nesting at Jamursba-Medi.

An average of about 16 percent of the JamursbaMedi females use the California Current's near-shore foraging areas. Benson reported that aggregations of jellyfish off Oregon are denser and larger during summer. In addition, the broad shallow area in the Gulf of the Farallones National Marine Sanctuary consistently exhibits greater abundances of leatherback turtles.

The Pacific council even voted to allow longlines within the Monterey Bay National Marine Sanctuary, where large congregations of leatherbacks feed, but NMFS blocked the idea. Benson's study concluded, “nearshore waters off California … represent an important foraging region for the critically endangered Pacific leatherback turtle.” He said they are especially important for the Jamursba-Medi turtles, “one of the largest remaining Pacific nesting populations.” 

The Pacific council now has its eyes on opening more ocean areas to longlines. These areas would be outside the 200-mile exclusive economic zone, but still within the leatherback's migration routes. Further action by the council is scheduled for March 2008

Paul Koberstein