Public Release: 

Sea Turtles Have Favorite Oceanic Routes

Cornell University

ITHACA, N.Y. -- While radio station traffic reporters track the annual migration patterns of Thanksgiving holiday celebrants, somewhere in the Pacific Ocean -- off the western coast of South America -- there are some leatherback turtles who have just begun to share their traffic information.

Sea turtle number 1109-B and some of her fellow leatherbacks have given humanity a fascinating glimpse into the long-distance migration patterns of vertebrate marine life. Scientists have learned that the turtles prefer specific ocean routes as if traveling an aquatic interstate highway. "They're all going along the same corridors," said Stephen J. Morreale, Cornell University doctoral candidate in zoology, who did the research for Cornell's New York Cooperative Fish and Wildlife Research Unit. "The existence of ocean corridors for sea turtles is important to the development of effective international conservation strategies."

The research, "Migration Corridor for Sea Turtles," published in the journal Nature (Nov. 28) was done by Morreale; Edward A. Standora, associate professor of biology, State University College, Buffalo; James R. Spotila, professor of bioscience at Drexel University; and Frank V. Paladino, chair, department of biological sciences at Indiana University-Purdue University, Fort Wayne, Ind.

At the nesting beaches in Costa Rica, Morreale and his colleagues tagged eight female leatherback turtles with small satellite transmitters designed to survive the crushing pressure of the ocean's deep water and buoyant enough to transmit a signal when a turtle reached the water's surface.

Attaching the transmitters to the turtles was not easy: the pliable, yet oily carapace -- the sea turtle's shell -- made attaching the tethered transmitter difficult. Attached transmitters lasted between three and 87 days, but that was enough time to provide the researchers the first record of the turtles' preferred path.

Efforts to save the leatherback turtle -- an endangered species -- have focused on their nesting areas and, hence, nesting females. Morreale said scientists have very little information on the males or the young of the species, or on where the females go after they nest. Tracking their movements by satellite could be one step that leads investigators to the rest of the leatherback population.

"We've put most of our energy into protecting their nesting beaches, but there is little we can do elsewhere unless we know where they are," Morreale said. "They are not highly visible at sea."

The corridor in the case of these particular turtles turns out to be at most a few hundred miles wide. It extends from Central America in the direction of the Galapagos Islands, and the researchers managed to track some of the turtles well beyond the Galapagos before the transmitters expired.

Even though the turtles have vast areas of ocean in which to thrive, humanity may be threatening the turtles' survival. International commercial fishing fleets venture well into the turtles' corridor. It is important to consider not only this species' nesting places and feeding grounds, but perhaps the interconnecting corridors as well.

"People might say, 'Oh, at least they have the whole ocean to live in.' With the discovery that turtles are concentrated within narrow corridors, what we're finding is that this may not be true," Morreale said.

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