Now, thanks to the tracking data, “the Sargasso Sea is emerging as an important habitat for sea turtles in their early life stages,” marking the region as critical for conserving the species, she said.
The Sargasso Sea, named for a free-floating genus of brown algae called Sargassum, is the only sea whose edge is defined by ocean currents, rather than land boundaries, according to the National Oceanic and Atmospheric Administration .
These observations, as well as sightings of the Florida-borne turtles in the east Atlantic, hinted that turtles may just make a big loop around the gyre before heading back to the U.S.
But Mansfield and her colleagues wanted to get hard evidence of this migration, while also pinning down how long the turtles typically stay offshore.
Satellite tags designed for adult turtles “looked like a brick” about the size of a cell phone, Mansfield said; but with the advent of small tags, about the length of a finger segment, the team could start tracking young turtles, she said.
The team initially attempted to attach the tags using the same adhesive they had used for the loggerheads, a kind of manicure acrylic that eventually peeled off as the animals grew.
The team tried many adhesives — those used to cement fillings in teeth, those used to attach theatrical prosthetics to skin, you name it — before finding one that would stick to the slippery turtles.
After ensuring the adhesive was safe and sticky enough, the team released their turtles into the western Atlantic and tracked them for an average of 66 days; they were able to follow several turtles for more than 100 days, and one for 152 days.
The seaweed provides camouflage for the teeny turtles, while also slowing the flow of water and thus allowing the sun to heat its surface.
But while a proportion of young sea turtles flock to the Sargasso, there’s still the question of why some swim toward the sea while others remain in the current, Mansfield said.
“I would guess those animals would be out there for maybe two to three years,” Wyneken said, but that’s a “pure guess,” she added.
Now that they’ve tracked turtles on their way to the Sargasso, the team could potentially search for turtles already living there and attach tags to them on-site, she said.
“It’s probably not just a green turtle story,” given that other juvenile marine animals also grow up among the seaweed, she added.