Where Sea Turtles Spend Their ‘Lost Years’
ERIK STOKSTAD | Science NOW
Now, researchers have published the first satellite tracking data from young sea turtles, charting a leisurely voyage under the sun. The youngsters idly float north along the Gulf Stream, then head toward the Azores. Along the way, they spend most of their time riding the waves, and the sun helps raise their body temperature. “The data from this handful of turtles could lead to some really important developments” in understanding turtle populations, says Nathan Putman, a turtle biologist at Oregon State University, Corvallis.
The early life of loggerheads and other sea turtles used to be called “the lost years,” because no one knew exactly where they went. But over decades, researchers pieced together the animals’ natural history from ship observations, the pattern of ocean currents, and other data. More recently, other scientists have studied isotopes from turtle tissue to analyze their diet and past locations and created computer simulations of their journey. The basic picture is this: Hatchlings head out to sea to avoid fish, sharks, and other predators. Once off the continental shelf, they eventually end up in a current, called the North Atlantic subtropical g. A few years later, they come back to their birthplaces on the East Coast of the United States.
The transmitters survived between 27 and 220 days, during which some turtles roamed as far as 4300 kilometers, the team reports today in the Proceedings of the Royal Society B. As expected, the turtles all headed north with the Gulf Stream, then most turned eastward around Cape Hatteras in North Carolina. The paths were consistent with what Putman’s computer models had predicted. The turtles weren’t single-mindedly heading toward the Azores, but looping around in small eddies and trying to avoid the coldest water. They also spent almost all of their time on the surface, and Mansfield suspects that this is to help stay warm. “It’s kind of a common sense thing,” Mansfield says. (They may also be waiting to develop the lung capacity for diving.)