Little is known about a turtle’s life at sea. Conservation efforts and studies of sea turtles have largely focused on nesting beaches. Upwell aims to learn more about how sea turtles travel the oceans. By understanding where they go and how they use different habitats, we can better advance protections for turtles at sea.
Turtle hatchlings enter the ocean and travel great distances before returning to their natal beach to nest, and only the females return to shore. This period between hatching and maturity is referred to as the “Lost Years” because researchers have limited data on a turtle’s life at sea.
Upwell’s Executive Director, Dr. George Shillinger, alongside Upwell Project Coordinator, Aimee Hoover M.S., first traveled to Pacuare Nature Reserve, one of the most productive leatherback nesting beaches in Costa Rica, to perform two hatchling tracking studies in 2016. They equipped Atlantic leatherback hatchlings with removable acoustic tags and tracked them for their first hours at sea. The data gathered was used to understand which direction the hatchlings instinctively swim toward. The tracking data was compared with ocean currents and revealed that the hatchlings actively swam against nearshore currents.
In 2018, the Upwell team, working closely with Dr. Helen Bailey (University of Maryland Center for Environmental Science) and first-year graduate student Nicole Barbour, returned to initiate another phase of the hatchling tracking project to explore the impact of environmental conditions (tides and wind) on hatchling speed and direction.
How do you track a baby turtle?
Researchers hire a local with a boat to motor past predators in the surf zone and reach calmer seas.
A non-invasive acoustic tag is attached to the hatchling’s back, using Velcro. The tag is detectable by a hydrophone attached to the boat. The acoustic receiver provides GPS data points, which can later be plotted on a graph. Two brightly-colored lightweight bobbers are attached to the tag with a tether; the bobbers help researchers see the hatchling in the water (Figure 1). They also drop a drifter in the water, which serves as a “control” indicating how the current pushes a passive object.
Researchers then follow the hatchling by motoring at a very slow speed. They must keep trained eyes on the baby turtle at all times. This is particularly hard in rough seas and requires extreme precision, patience and a stomach of steel. For a first-hand perspective, read, “Nausea and Curiosity: An Account of Real Sea Turtle Fieldwork,” from research assistant, Max Gotts.
The research team records the environmental variables important to the study. At the end of the study, Upwell researchers remove the acoustic tag and Velcro attachment. They release the hatchling to swim away freely, now safely beyond the predator-rich surf zone. Researchers also need to hunt down and retrieve the drifter.
Throughout the course of the study 52 hatchlings were tracked. Researchers found that in faster currents, hatchlings had bursts of higher speeds and swam away from shore, indicating attempts to correct position. Thus far, the results suggest that hatchlings may be purposeful in their direction as they enter the ocean, following a relatively consistent orientation during their first hours at sea.
“The Lost Years” remains one of the biggest mysteries of sea turtle biology, but with better knowledge of where hatchlings are going, we will be able to help advance protections for sea turtles during this critical life history stage.