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Baby Sea Turtles Spend ‘Lost Years’ in Sargasso Sea

Researchers used tracking tags to solve the mystery of where young green sea turtles go after they hatch on the beach

A young green sea turtle with a solar-powered satellite tag that was used to track it to the Sargasso Sea. (Gustavo Stahelin, UCF MTRG; Permit number NMFS-19508)
smithsonianmag.com

The life of a green sea turtle starts off perilous. If the tiny, newly hatched turtles survive the gamut of seagulls, crabs and other animals looking to munch them on their way to the sea, the saucer-sized marine reptiles have to contend with breaking waves and an ocean seemingly filled to the brim with new potential predators. But once the lucky hatchlings have escaped the dangers near shore, scientists lose track of them until they return to beaches as the sea turtle equivalent of teenagers. Researchers even refer to this segment of sea turtle life as “the lost years.”

Now, a new study in the journal Proceedings of the Royal Society B finds that after hatching on beaches along the coast of Florida and heading out to sea, young green sea turtles spend their early lives nestled among floating tangles of amber-yellow seaweed in the North Atlantic’s Sargasso Sea, reports Nicoletta Lanese for Live Science.

The Sargasso Sea is so named because of the mats of free-floating sargassum seaweed that grow there. Unlike most seas, the Sargasso doesn’t have strict boundaries but is loosely formed by the swirling currents of the North Atlantic gyre.

To follow the young green sea turtles to this open ocean oasis of food and refuge, researchers glued tracking devices to the shells of 21 three-to-nine-month-old green sea turtles, reports Isaac Schultz of Gizmodo. Once fitted with solar-powered tracking tags about the size of a AA battery, the researchers released the turtles back into the sea about ten miles offshore from the beach they were born on.

Katherine Mansfield, a biologist at the University of Central Florida and lead author of the new paper, tells Gizmodo that this is the first time green sea turtles of this age and size have ever been tracked.

Fourteen of the 21 turtles hitched a ride north on the Gulf Stream current before breaking off and heading into the western or northern Sargasso Sea. According to a statement, previous research has also tracked "toddler" loggerhead sea turtles to the Sargasso.

The results offer new evidence that the Sargasso Sea is critical habitat for sea turtles and could guide future conservation efforts.

“These studies in which we learn where little sea turtles go to start growing up are fundamental to sound sea turtle conservation,” says Jeanette Wyneken, a biologist at Florida Atlantic University and co-author of the research, in a statement. “If we don’t know where they are and what parts of the ocean are important to them, we are doing conservation blindfolded.”

Mansfield tells Gizmodo that the big question now is how long the sea turtles stay in the sargassum—the longest-lived tag in the current study lasted just 152 days. Future studies will look to capture and tag turtles already lounging in the sargassum to see how long they stick around, according to Live Science.

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