Scientists have used satellite trackers to shed light on the “lost years” of young sea turtles, a period previously shrouded in mystery. For decades, researchers have puzzled over the lives of these creatures between the time they hatch and their return to coastal areas as near-adults. This period can last anywhere from one to 10 years.
A new study, published in Proceedings of the Royal Society B, offers some answers. Marine scientists, led by Kate Mansfield of the University of Central Florida, attached GPS tags to the shells of 114 young turtles in the Gulf of Mexico. The species tracked included endangered green turtles, loggerheads, hawksbills, and Kemp’s ridleys.
The process of tagging the turtles involved searching for them amongst floating algae in small boats. While the tags eventually detached due to the rapid shell growth of the young turtles, they transmitted location data for several weeks to months.
“We’ve had massive data gaps about the early baby to toddler life stages of sea turtles,” Mansfield explained. “This part of their long lives has been largely a mystery.” The data collected is challenging long-held assumptions about these early life stages. Co-author Katrina Phillips, a marine ecologist at the University of Central Florida, noted that the tags detached because “the outside of a young turtle’s shell sheds as they grow very quickly.”
Scientists long thought that tiny turtles drifted passively with ocean currents, literally going with the flow.
“What we’ve uncovered is that the turtles are actually swimming,” said co-author Nathan Putman, an ecologist at LGL Ecological Research Associates in Texas.
The scientists confirmed this by comparing location data of young turtles with the routes of drifting buoys set in the water at the same time. More than half of the buoys washed ashore while the turtles did not.
“This tiny little hatchling is actually making its own decisions about where it wants to go in the ocean and what it wants to avoid,” said Bryan Wallace, a wildlife ecologist at Ecolibrium in Colorado.
The tracking data also showed more variability in locations than scientists expected, as the little turtles moved between continental shelf waters and open ocean.
Besides the painstaking work of finding turtles, the trick was developing flexible solar-powered tags that could hang onto shells long enough to send back data.
“For years, the technology couldn’t match the dream,” said Jeffrey Seminoff, a marine biologist at NOAA who was not involved in the study.
The findings give biologists a better idea of how young turtles use the Gulf of Mexico, a critical region for four species of endangered sea turtles.
“It’s not that the sea turtles were ever lost, but that we had lost track of them,” said Jeanette Wyneken at Florida Atlantic University, who had no role in the research.
