Tracking a Giant Leatherback Turtle’s Meanderings May Lead to New Strategies for Its Species’ Survival

Duke marine biologists hope signals from a satellite transmitter harnessed to a nesting leatherback turtle named Beatrice will help them identify habitats critical for the endangered species’ recovery.

Tuesday, June 15, 2004/ JUNO BEACH, FL. – Each year, dozens of leatherback sea turtles, the largest turtle in the world, come ashore between March and July to lay their eggs under cover of night in the sand at Florida’s Juno Beach, the most important leatherback nesting colony north of St. Croix in the Virgin Islands.

Scientists know that the endangered turtles will return to the beach every 10 nights to lay new clutches of eggs, with each turtle laying six clutches a year on average.

But where they go between and after the nestings is still something of a puzzle – one that scientists from the Nicholas School of the Environment and Earth Sciences at Duke University are working to piece together.

With the help of two conservation groups, a high-tech telemetry-equipped harness and a far-roaming giant leatherback named Beatrice, the Duke team hopes to identify offshore habitats critical for the endangered turtles’ survival.

“Determining where leatherbacks like Beatrice go – where their foraging grounds, migratory corridors and inter-nesting areas are – is vital to our efforts to develop a management strategy for their recovery,” says Scott A. Eckert, assistant research scientist at the Nicholas School and director of science for the Wider Caribbean Sea Turtle Conservation Network (WIDECAST), a network of Caribbean sea turtle scientists, conservationists and policy analysts based at the Duke University Marine Laboratory in Beaufort, NC.

The Nicholas School and WIDECAST are collaborating with the Marinelife Center of Juno Beach on the tracking project.

Duke PhD student Kelly Stewart, studying Florida leatherbacks for her dissertation, and her colleague Chris Johnson of the Marinelife Center started The Leatherback Project at Juno Beach in 2001. Sighting of leatherback nests on Florida beaches had risen dramatically over the past decade, and Johnson and Stewart wanted to know why – and what the increased sightings might mean for conservation efforts.

To track the turtles leaving Juno Beach, they teamed with Eckert, one of the world’s top experts on turtle monitoring technologies.

Based on Eckert’s earlier studies, scientists believe that most Florida leatherbacks stay fairly close to the shore, rarely going out past the continental shelf during the time between nestings. After nesting, scientists believe they swim north along migratory corridors up the Atlantic seaboard, a route that takes them repeatedly into the path of commercial fishing fleets.

But physically observing and documenting the migratory routes and other critical habitats had until recently been virtually impossible, since the turtles are only infrequently visible, when they surface for air. “It’s like trying to track a lightning bug through a forest at night,” Eckert says.

To solve the problem, in the early 1980s he devised a flexible turtle harness which could hold data-gathering instruments that transmitted location signals each time the turtle surfaced. In the early 1990s, he improved the harness’ functionality through the use of satellite telemetry. Versions of the harness, which looks like a belt and suspenders and can be fitted snugly under a leatherback’s belly and over its skin-covered carapace, have now been fitted on more than 300 turtles.

Johnson and Stewart fitted Beatrice with hers on May 21, and have been monitoring her whereabouts ever since. Daily updates are posted on the Web at www.floridaleatherbacks.com.

Made of nylon webbing similar to the material used for backpack straps, the harness is designed to stay on the turtle for two years, Eckert says, although there is always the danger it will snap or slip off, or that the transmitter will be damaged if the turtle is entangled by fishing gear.

He and his colleagues have had some success using the harnesses to track other leatherbacks from the Juno Beach colony, he says, “but we are still far from having the complete story. The sample size to date is still relatively small, so any data from Beatrice will add very significantly to our knowledge.”

Ideally, scientists will be able to track Beatrice for the full two years between nesting seasons, he says, and then get similar data from at least 25 other Florida leatherbacks. “That would allow us to present some fairly conclusive findings about their critical habitats and better anticipate the impact fisheries or other human activities may have on them,” Eckert says.

Stewart’s faculty advisor, Larry B. Crowder, is the Stephen Toth Professor of Marine Biology at the Nicholas School and studies the effects of longline fisheries on leatherbacks. Shana Phelan, a Duke coastal environment management student, also works of the Leatherback Project.

To document turtle activity, Stewart, Johnson and Phelan patrol Juno Beach from 9 p.m. to 6 a.m. nightly during nesting season, watching for the turtles to emerge from the waves and marking their new nests.

Able to recognize individual turtles by flipper tags or microchip ID tags, the spotters maintain detailed logs of the turtles nocturnal activity and often given them human nicknames, noting, for example, that “Christina came back tonight and nested successfully. We have seen her four times this season.”

To increase public awareness of the project, and of the plight of the leatherbacks, their field notes are posted each morning on the project’s Web site. Visitors can also print out maps and track Beatrice’s movements, like they might do with a hurricane.

Patrolling nightly for nine hours at a stretch can be grueling, but Stewart is confident their efforts will pay off. The data gathered by the spotters and from the tracking harnesses will help scientists and conservationists develop a strategy for safeguarding breeding-age leatherback adults from the June Beach colony.

“Beatrice is just the beginning. Next season, we will equip several leatherbacks with transmitters and monitor their every movement during that 10-day period between nests,” she says.

The bottom line, she adds, is the hope that Beatrice and the colony’s other migrating matriarchs will live long enough to breed again, in two to three years, on the warm beaches of Juno Beach.

Stewart can be reach at kelly.stewart@duke.edu. Eckert can be reached at (252) 504-7598 or seckert@widecast.org. For help reaching them, contact Tim Lucas at (919) 613-8084 or tdlucas@duke.edu.