Leatherback Sea Turtle Tagging at Playa Grande, Costa Rica

by Diane Richards

 George Shillinger kneels in the soft sand of Playa Grande beach, his eyes fixed on a huge female leatherback that is scooping a depression nearby with her flippers. It's nearly dawn and Shillinger has waited diligently with his TOPP tagging teammate, Bryan Wallace throughout the Costa Rica night for just this moment.

The eco-tourists have finished observing the evening's nesting, and this turtle's excavation is – so far – going well. Everything must remain just so however, for if the sandy walls of her nest give way, the leatherback will abandon this attempt, which may be her last for the night. It is always a waiting game, and the nights are long, but Shillinger is patient. For him, the task is a labor of love.

"You tend to be sleep deprived because the tagging is done at night, and you have to work in the dark," explained the 37-year old Stanford Ph.D. student in a recent interview. But the rich black nights offer meteor showers, and camaraderie with other researchers and locals, the "wonderful people" who are all working to save the threatened sea turtle. And there are other rewards, as well.

"Leatherbacks are special," says Shillinger, who has also helped apply TOPP tags to tunas and sharks. "It's beautiful to see them crawl out of the water onto the beach to lay their eggs." They are huge and timeless and when they are ready to fill their nests, "they grunt and excrete salt water from glands under their eyes, which makes them look like they are crying. It is very moving."

Back on the beach, the excavation is complete. For a moment, the two men hold their breaths. Success! The crater holds and the turtle will lay her eggs, depositing her precious cargo in the perfect, fresh cavity she's created. Now is the time for the taggers to spring into action. While the turtle is in a state of egg-laying torpor the two men can affix the tag to her back with relative ease. The big female is so immersed in depositing her eggs, the application process barely seems to register.

The tag is a sophisticated device; one of TOPP's CTD satellite-communicating data loggers. It will transmit tracking data to an overhead satellite, ultimately allowing Shillinger and his colleagues back at Hopkins Marine Lab in Pacific Grove to monitor the subsequent beach visits during the remainder of the nesting season, and the female's long sojourn in the open ocean that follows.

By tracking the movements of female sea turtles to and from the beach during nesting season, researchers will document the times and zones where the nesting leatherbacks are most vulnerable to off-shore fishing nets. Similarly, elucidating the migratory corridors in which the animals travel between nesting seasons will help protect them in the open ocean.

"If we don't take steps, the leatherback sea turtle could go extinct on our watch," notes Shillinger. With TOPP data, resource managers have the opportunity to take concrete steps right now. "When you watch the turtles return to the ocean after nesting," says Shillinger, "you're seeing something ancient. It's like touching a bit of the past."

HI DIANE

Your article brought back that wonderful experience of being on the beach watching the egg laying process and on one occasion being with George and Bryan when they were attaching the telemetry. It will be hard to beat that!
Marie