Washington -New insights have been gained into the “lost years” of loggerhead turtles. Tiny satellite tags have tracked months-old animals in the uncertain period when they leave US coastal waters and head out into the wider Atlantic Ocean.

The data suggests the loggerheads can spend quite some time in the Sargasso Sea, possibly living in amongst floating mats of sargassum seaweed. The observations are reported in a journal of the Royal Society. “This has been a fun study because the data suggest the turtles are doing something a little bit unexpected to what everyone had assumed over the past few decades, and it boils down to having the right technology to be able to follow the animals,” said lead author Dr Kate Mansfield from University of Central Florida, Orlando.

Scientists have long struggled to track the earliest years of Atlantic loggerheads (Caretta caretta). After emerging from their nests on Florida’s beaches, the infant turtles, or neonates, make a dash for the water and head out on a great adventure. Precisely where they go and what they do with their time before returning as large juveniles to the US seaboard has been something of a mystery.

Genetics studies, bycatch, strandings and opportunistic sightings offshore had given broad hints - that they travel in a huge circle within the currents associated with the North Atlantic subtropical gyre, reaching the Azores and Cape Verde before heading back to the Gulf of Mexico and Florida. Tracking by satellite would give more definitive answers, but attaching data tags to turtles that are just a few months old, and growing rapidly, has been a struggle.

And it is with this new data that the scientists can see the young turtles dropping out of the gyre’s predominant currents into the middle of the Atlantic – into what is often referred to as the Sargasso Sea. The way the tags worked indicated also that the loggerheads mostly stayed at the sea surface.

This could be seen in the temperature recordings as well, although these readings were quite a bit higher than expected. This has led the team to hypothesise that the turtles are living in and around the great mats of sargassum found in the central Atlantic.