Just two weeks after she nested on a Caribbean beach in Costa Rica, a hawksbill sea turtle navigated 200 miles north to shallow waters off the coast of Nicaragua. Scientists are keeping tabs on her speedy swim via satellite tracking technology. On July 20, they attached a small transmitter to the turtle's shell after she deposited eggs into a cavity dug in the black, volcanic sands of Costa Rica's Tortuguero National Park.

Another hawksbill and two green sea turtles were also outfitted with the devices. Now, each time the turtles come to the water's surface to breathe, signals are sent to a satellite in space, which beams them to receivers at the Caribbean Conservation Corporation (CCC), a Florida-based nonprofit group.

The CCC and the Florida Marine Research Institute are conducting the sea-turtle migration study in collaboration with Costa Rica's natural resources agency, MINAE. CCC has attached ID tags to sea turtles for four decades in order to collect information about where the reptiles navigate after nesting in Tortuguero. Fishermen in the Caribbean collect the tags and mail them to the CCC.

According to Roxana Silman, director of CCC's Costa Rica office, information gathered from returned turtle tags tells scientists that the animals have reached point B from point A, while the satellite data reveal their paths in between. "We then can design regional management plans that will improve sea turtle conservation through better understanding of their migrations and biology," she says.

The U.S. National Oceanic and Atmospheric Administration and the National Marine Fisheries Service (NMFS) are providing technical assistance and

funding to the satellite-tracking program. NMFS's George Balazs, who helped train researchers in Tortuguero, explains that the agencies are also training researchers elsewhere in the region how to attach transmitters to hawksbill turtles.

More green sea turtles (Chelonia mydas) nest in Tortuguero than any other of the seven species. All are endangered due to human activities, including development on nesting sites, commercial fishing, and hunting for meat and eggs. Hawksbill turtles (Eretmochelys imbricata) were hunted for centuries for their strikingly marked shells.

Silman notes that until 1999, Costa Rica allowed hunting of green sea turtles, once an important source of protein for Caribbean residents. While a limit was placed on how many turtles could be killed, it was impossible to know if turtles were legally or illegally caught. Conservationists successfully lobbied to impose a complete ban, although illegal hunting still exists. CCC launched an educational campaign and is working with local fishing cooperatives to help develop alternative income sources. Silman believes these efforts have helped lessen the poaching problem.

Ligia Montejo, co-owner of Manatí Lodge just outside Tortuguero National Park, concurs. "Years ago, people here made their livings from hunting sea turtles," she says. "Now they make more money by working in tourism, taking people out to see the nesting turtles or guiding visitors through the park."

But now Costa Rica's sea turtle population faces a new threat: planned oil exploration off the Caribbean coast. According to CCC studies, petroleum can damage sea turtle skin, lungs, stomach, and eggs. "Newborn sea turtles are particularly vulnerable to the effects of petroleum," Silman notes. Several conservation groups have filed a lawsuit against MINAE, which awarded an oil-drilling concession to the U.S. firm MKJ-Xplorations. @