Upwell and Aquarium La Rochelle released an initial cohort of 10 juvenile loggerheads in July of 2024. The tag of the turtle named Charles Darwin set a record by transmitting for over a year! As you can see in the map below, Charles seemed headed for the Azores at the time the tag stopped.

Some of the other turtles released with Darwin, all of which were named after European scientists, also had impressive tag transmission durations. The tags on turtles Archimede and Nicolas Copernic continued to transmit for an astounding 334 and 311 days respectively, beating the previous record of 188 days set by the tag of Peniche, a loggerhead released in the Azores in 2021.

At the end of June, Upwell Executive Director Dr. George Shillinger joined our Aquarium La Rochelle collaborators to tag and release 9 more rehabilitated juvenile turtles. With increasing sample size, we are able to generate more robust statistics and develop stronger hypotheses. We can then integrate environmental datasets to examine correlations in turtle’s horizontal and vertical movements in relation to environmental factors such as sea surface temperature, productivity or concentrations of chlorophyll, the speed of currents, sea surface height, or bathymetry.

The tracking data and analyses give us rare insight into the time juvenile loggerheads spend foraging and growing (up to 15 years) at sea, which is often referred to as their “Lost Years.” We use this insight to calibrate various models that can help us predict sea turtle habitat use or even population trends - models that aim to support effective and targeted conservation efforts.