|all articles latest | past | articles by topics | search wildnews|
wild news on wildsingapore
Francisco Chronicle 26 Sep 06
Rare giant turtles roam San Francisco
Glen Martin, Chronicle Environment Writer
Sea turtles the size of sports cars are swimming off the Marin County coast, chowing down on jellyfish and thrilling boaters lucky enough to spot them.
Leatherback turtles typically visit the California coast in the fall and congregate around Monterey Bay. This year, however, the turtles could be zeroing in on the Marin Coast instead.
The leatherback, an extremely rare reptile that tolerates waters too chilly for other sea turtles, can grow up to 9 feet long and weigh a ton.
It's unclear why it's showing up so far north. Scott Benson, a research biologist with the National Marine Fisheries Service who specializes in leatherbacks, said he hoped to search for turtles soon in the waters off Marin County. Benson and his crew plan to put a satellite telemetry tag on at least one of the highly migratory creatures to track its travels around the Pacific Ocean.
"You usually start hearing of sightings sometime in late summer or early fall," he said. "Last year, they were off the San Mateo coast, and now they appear to be north of the Golden Gate. Wherever they go, they're looking for jellyfish."
At least one large leatherback recently was spotted fairly close to the Point Reyes Peninsula, gobbling jellyfish the size of dinner plates.
"It was huge," said San Francisco resident Lisa Mullerauh, who spotted the animal while fishing from a Boston whaler with her brother, John Rauh of Muir Beach. "It had maybe a 5- or 6-foot shell," said Mullerauh, who took pictures of the turtle. "It was so low-key -- just floating there, eating these big, brown, footwide jellies like they were going out of style. We were only 20 feet from him, and he didn't seem to even notice us."
Leatherbacks are placid and seldom show much alarm at being approached, and they can be difficult to spot. "These are cryptic animals," Benson said. "They don't really have a pronounced profile in the water, and they can be hard to find."
Leatherbacks are found around the globe, but their numbers have dropped drastically in recent years.
The Pacific population is especially at risk, said Karen Steele, the campaign coordinator for Save the Leatherback, a Marin County-based group. "Pacific leatherbacks have decreased by about 95 percent in the past 20 years," Steele said. "There may be as few as 2,300 breeding females left."
The decline of the species is largely due to human collection of their eggs on their nesting beaches and the killing of adults by drift net and long-line fisheries, she said.
Benson hesitated to put a figure to the Pacific leatherback population but acknowledged that the species has dwindled precipitously. In a good year, he said, perhaps 300 leatherbacks visit coastal waters north of Point Conception in Southern California.
Benson said there are two stocks of Pacific leatherbacks: one nesting on beaches in the Indonesian province of Papua and the other at sites in Costa Rica and Mexico. The turtles that show up in California waters come from Asia, he said; the Costa Rican and Mexican leatherbacks typically head to South America.
Benson said researchers have worked with Papua Indonesian villagers during the last few years to protect the turtles' nesting sites.
"We think we're going to have to make a bigger commitment," he said. "The villagers need money. They're getting offers from timber companies to log their land, and that would definitely damage the nesting habitat. It's a real race between natural resource demand and the turtles."
Some turtle deaths are also linked to trash -- particularly plastic bags, which the turtles mistake for jellyfish.
Steele said another potential threat to the leatherbacks is the fisheries service's consideration of a drift gill net fishery for California and Oregon from mid-August through mid-November.
Drift gill nets are large mesh nets suspended in the water to catch swordfish and other large predator fish by their gills. In 2001, the marine fisheries service banned such fishing for those months after agency staffers determined leatherbacks could be harmed.
Mark Helvey, an assistant regional administrator for the fisheries service, said any new drift net fishery would be limited in scope. Only about five boats would be allowed to fish at any one time, he said, and fishing would stop if two turtles or one whale of any of three species -- short-finned pilot whale, sperm whale or humpback whale -- were killed.
The agency should make a final decision on the proposed fishery by Oct. 2, Helvey said. Steele said the drift net ban has been effective in protecting leatherbacks, and she said it should remain in place.
"There hasn't been a single observed leatherback death attributed to fishing since the closure went into effect," she said. "With leatherbacks remaining in such serious jeopardy, this isn't the time to loosen regulations."
The leatherback turtle
Scientific name: Dermochelys coriacea
Size: Leatherbacks are the largest turtles. They can grow to 9 feet and weigh more than a ton.
Description: Adults are usually black with a pinkish, white belly and pink and white spots on the top of their head. Their front flippers are larger than other sea turtles' and lack claws.
Range: Leatherbacks are found throughout the globe, although the Pacific populations are found in Asia and along the coastline of North and South America. They're very migratory animals. They can stay underwater for 30 minutes and dive up to 4,000 feet.
Diet: They favor jellyfish but also feed on sea urchins, squid, algae and seaweed. Their throats have spines that prevent prey from escaping.
Reproduction: Only an estimated 2,300 reproducing Pacific females remain. They lay about 100 eggs on sandy, tropical beaches. The nesting period may last between one and two weeks. Two-inch hatchlings emerge after about two months.
Threats: Nesting sites are increasingly destroyed by pollution and development. Longline fishing - which employs 60-mile lines of baited hooks - and drift gill net fishing also ensnare the turtles. They were listed as endangered under the Endangered Species Act in 1970.
Mini Cooper: 11.9 feet, 2,524 pounds
Leatherback turtle: Up to 9 feet, 2,000 pounds
Key leatherback nesting sites remaining in the Pacific
1 Terrenganu, Malaysia
2 War Mon, Papua, Indonesia
3 Jamursba-Medi, Papua, Indonesia
4 Papua New Guinea
5 Solomon Islands
6 Baja California, Mexico
7 Michoacan, Mexico
8 Guerrero, Mexico
9 Oaxaca, Mexico
10 Las Baulas, Costa Rica
Sources: U.S. National Oceanic & Atmospheric Administration; U.S. Fish and Wildlife Service; Mongabay; MiniUSA.com - compiled by Johnny Miller, Chronicle Research Librarian
Related articles on Wild shores and Sea Turtles
|News articles are reproduced for non-profit educational purposes.|
website©ria tan 2003 www.wildsingapore.com