How Researchers Track the 'Lost Years' of Baby Sea Turtles

Biologists Kate Mansfield and Jeanette Wyneken have come up with an ingenious method to keep satellite tags attached to the shells of young loggerhead turtles as they grow. (Photo: Jim Abernethy).

Biologist Kate Mansfield has spent much of her career meticulously charting the life histories of endangered Atlantic sea turtles the way a master genealogist pieces together a complex and unwieldy family tree.

Sea turtles have existed for more than 100 million years, helping maintain a balanced marine ecosystem, but until recently researchers knew little about them. One thing in particular remained a mystery: Where do hatchlings go after disappearing into the deep ocean waters off the East Coast of the U.S. and South America before returning years later as large juveniles?

“The oceanic stage has been very understudied,” Mansfield says, “in part because the turtles are too small to see by aerial survey, and the technology hasn’t been there to track them. Knowing where they go, what they do and how they interact with the environment can help us really target conservation efforts.”

Determined to chronicle these “lost years,” Mansfield, who works for the Marine Turtle Research Program at the University of Central Florida in Orlando, and Florida Atlantic University biology professor Jeanette Wyneken recently stumbled upon an unlikely solution to help them track baby loggerheads departing from Florida beaches. Call it high-tech innovation meets low-tech ingenuity.

Mansfield and Wyneken knew they wanted to monitor the hatchlings via a satellite tracking device and were excited to find a solar-powered tag small enough to fit on the tiny shells. But there was one problem. Because turtle hatchlings grow so fast — eventually reaching about 36 inches and weighing some 250 pounds — nothing stayed glued to their constantly peeling and expanding shells longer than a couple of weeks.

The women began searching for ways to keep the satellite tags in place long enough to collect more data. They tried various adhesives, to no avail. They outfitted the babies with tag-holding harnesses, and even experimented with special swimsuits dreamed up by a research assistant who’d studied fashion design. But the hatchlings burst out of both in no time.

Kate Mansfield

Then the women had an epiphany. Turtle shells are made from the same material as fingernails: keratin. Anything that stops fingernails from peeling would likely do the same for turtle shells.

“Jeanette is known for her painted toenails decorated with little waves and stuff,” Mansfield says. “Once we made the keratin connection, she called her manicurist, who recommended trying acrylic nail filler.”

Mansfield and Wyneken headed to their local drug store to buy some, then proceeded to paint it on the hatchling’s shells to prevent peeling. Afterward, they secured the satellite tags using strips of old wetsuit, toupee glue and waterproof aquarium silicone sealant. It worked like a charm.

“Instead of staying on for only two or three weeks, the tags held for several months,” Mansfield says. “We were pretty excited.”

So where do they go?

Loggerheads live in many of the world’s oceans, and each group follows its own migration patterns. Scientists have long believed that hatchlings living along the eastern U.S. journey around the North Atlantic Subtropical Gyre, a circular system of ocean currents that move up the U.S. coast, northeast toward Iceland, down the west coast of Europe and Africa and back around again.

But after following their satellite-tagged hatchlings for many months, Mansfield and Wyneken were surprised to find a different scenario. Turns out loggerheads actually take a lengthy break from the gyre merry-go-round to chill in the Sargasso Sea, a giant patch of ocean at the center of the gyre currents named for its floating mats of brown algae called Sargassum.

“Sargassum provides food, shelter and also a thermal benefit as the turtles bask in the sun on the sea surface,” Mansfield says. “That’s important for little cold-blooded animals trying to kick-start their metabolisms and grow quickly so they don’t get eaten.”

Mansfield and Wyneken hope their findings lead to better protection for North Atlantic loggerheads and their favorite floating habitat. But the study also adds a new geographic wrinkle. Sargassum actually originates in the Gulf of Mexico before looping around Florida and riding the gyre currents to the Sargasso Sea. So any loggerhead conservation efforts must also now include protecting the Gulf of Mexico from environmental threats like oil spills.

Turtle treasures

Mansfield, who once dreamed of becoming an underwater archaeologist, also studies other sea turtles. Right now, she’s researching where Brazilian loggerheads go after disappearing into a similar gyre in the South Atlantic.

She’s also preparing a paper on the lost years of green turtles and studying baby leatherbacks — both of which require different satellite-tagging methods because their shells are made of other materials.

“I really wanted find shipwrecks and gold doubloons when I was growing up,” she says. Instead, she’s uncovering treasures of a different sort — knowledge that could help save some of the planet’s most vital and enduring marine reptiles.