The ‘lost years’ – new evidence shows young sea turtles may not be going with the flow

After hatching, young sea turtles are rarely seen for the next 2-10 years when they return to coastal waters to feed and reproduce. With so little known about these early years in a turtle’s life they have been aptly dubbed the ‘lost years’.

For a long time it was assumed that young turtles spent these ‘lost years’ drifting passively with the ocean currents, although a few are known to hitch a ride on floating beds of Sargassum. New research has, however, shown that turtles under 2 years old are actively swimming during their dispersal.

Twenty four wild caught ‘toddler’ Green turtles (Chelonia mydas) and 20 Kemp’s Ridley turtles (Lepidochelys kempii) were fitted with solar powered tags that were tracked for around 2-3 months before they shed cleanly from the turtle’s shells. Next to each turtle a passively drifting surface buoy was also deployed and tracked by satellite. When the movements of both the turtles and the passive drifting buoys were compared the paths of both differed considerably – by as much as 125 miles in the first few days. The authors believe that the active dispersal by the turtles helps them to reach and/or remain in favourable habitats.

 

Track of a turtle

Figure 1 – Showing the difference between the passive drifting buoys (blue lines) and a tagged turtle (green line)

Dr Nathan Putman  of the National Oceanic and Atmospheric Administration (NOAA), and lead author of the study says,

“All species of sea turtles are endangered or threatened under the Endangered Species Act; knowing their distribution is an essential part of protecting them. With a better understanding of swimming behaviour in these yearlings we can make better predictions about where they go and what risks they might encounter.”

Dr Kate Mansfield, director of the University of Central Florida’s Marine Turtle Research Group and co-author of the study says,

“The results of our study have huge implications for better understanding early sea turtle survival and behaviour, which may ultimately lead to new and innovative ways to further protect these imperiled animals”.

Reference:

Putman & Mansfield (2015). Direct evidence of swimming demonstrates active dispersal in the sea turtle ‘Lost Years’. Current Biology.  DOI: 10.1016/j.cub.2015.03.014

Cover image and Figure : University of Central Florida and National Oceanic and Atmospheric Administration

 

 

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A nature writer and ecological advisor with wide experience of writing about wildlife and working in freshwater, marine and terrestrial environments. Website: www.phoebecarter.co.uk. Twitter: @DrPhoebeCarter

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