Friday, December 4, 2009
The rare olive ridley turtle was first spotted Nov. 25 in the Sea Drift area of the beach. The 60-pound female with a 2-foot-long shell was taken to the Marine Mammal Center in the Marin Headlands, where it was stabilized with fluids, vitamins and antibiotics.
"This is definitely a rare find, one of only three live olive ridley turtles I know of reported in the scientific literature since 2001 along the Central California coast," said Todd Steiner, a biologist and executive director of the Sea Turtle Restoration Project, based in Marin County.
Steiner said the turtle was suffering from what is known as cold-stunning, a unique state of suspended animation that can allow a turtle to survive for months in cold water. The big green reptile was covered with algae, barnacles, shore crabs and ghost shrimp, indicating that it had been floating for a long time. Subsequent blood tests revealed it was malnourished.
"I don't know if it would have had enough strength to get back into the water," Steiner said. "It would have died on a cold night if it didn't get back in the water."
Olive ridleys, whose shells can grow to 2 1/2 feet long and which can reach 100 pounds, are one of seven species of giant sea turtle, but their extraordinary nesting habits separate them from the others.
During the mating season between July and December, large groups of them gather offshore of nesting beaches in Mexico and Costa Rica. Then, all at once, they come ashore to lay eggs in what is known in Spanish as an arribada, or arrival.
Their nesting habits have historically made them easy prey. Steiner said ocean voyagers used to collect turtles because they could keep them alive for months without feeding them, giving sailors an endless supply of fresh meat. Starting in the 1960s, as many as 75,000 turtles a year were being killed until laws were passed to prevent the practice. Their numbers were also greatly reduced by development.
Sea turtle sightings in the Bay Area are not unheard of. Steiner, whose organization was instrumental in closing down a sea turtle slaughterhouse in the state of Oaxaca in 1990 (sea turtles have since been protected in Mexico), said leatherback turtles have been seen in Monterey and around the Farallones.
Twenty-six sea turtles in all have been treated at the Marine Mammal Center since the early 1970s, said Bill Van Bonn, the staff veterinarian.
The last time an olive ridley was seen was on Thanksgiving Day 2002, when one suddenly ambled out of the chilly waters onto Shell Beach, in Tomales Bay, to the amazement of several witnesses, including one of the Bay Area's foremost sea turtle biologists who happened to be at the beach with his family.
Just like in 2002, an El Niņo weather pattern is building up this winter. Steiner said turtles are uniquely susceptible to climate changes in the water and on land. Gender is determined by the temperature at which sea turtle eggs hatch, he said.
The olive ridley is so rare in Northern California that the long distance traveler found on Stinson Beach had to be transported to SeaWorld in San Diego, where biologists are more familiar with sea turtle rehabilitation techniques. She was listed Thursday in stable but guarded condition, but aquarium staff said she was getting stronger.
"It's hard to say where her journey started, but she was certainly a long way outside her expected path," Van Bonn said. "Fortunately she showed up where she was spotted."
Olive ridley turtle
Olive ridley turtles have historically been abundant in tropical regions of the Pacific, Atlantic and Indian oceans. Prior to 1950, an estimated 10 million olive ridleys nested on the Pacific coast of Mexico. In the mid-1960s, an olive ridley fishery developed in Mexico and Ecuador, and the taking of eggs and females also increased, which devastated the population. Nesting populations were severely depleted until 1990, when the Mexican government banned the taking of olive ridleys. La Escobilla, Oaxaca, is now Mexico's primary arribada nesting beach.
Source: NOAA Fisheries
E-mail Peter Fimrite at firstname.lastname@example.org.
This article appeared on page C - 1 of the San Francisco Chronicle