Shillinger is the first author of a paper published in the July 15 issue of Public Library of Science Biology and part of a large team of biologists and physical and biological oceanographers from the United States, France and Costa Rica who worked on the multiyear study.
The leatherback tagging study is part of the Tagging of Pacific Predators (TOPP) program, which has tagged other animals including the white shark, bluefin tuna, black-footed albatross and elephant seal. TOPP is part of the Census of Marine Life, a global network of researchers in more than 80 nations engaged in a 10-year scientific initiative to assess and explain the diversity, distribution and abundance of life in the oceans.
Over three field seasons, from 2004 to 2007, Shillinger, co-author Bryan Wallace (Duke University and Conservation International) and a team from Playa Grande National Park outfitted 46 females on the beach with small tags that emitted signals that were picked up by satellites, enabling the team to track the turtles' location.
Shillinger and his colleagues worked with research oceanographers and co-authors Steve Bograd and Helen Bailey at the National Oceanic and Atmospheric Administration and Daniel Palacios, also at NOAA but from the University of Hawaii. They examined turtle speeds and movements in relation to the distribution and strength of the equatorial current system and found that the turtles increased their speeds as they moved through high-energy areas.
But how much of the turtles' trajectory was from being pushed around by the currents and how much was the result of their own free will, they couldn't tell until French oceanographer and co-author Philippe Gaspar analyzed the data using a method he had developed to make that distinction. Once the effect of the currents had been factored out, the turtles were found to be consistently heading in a south-southwesterly direction.
Year after year, the
|Contact: Dan Stober|