As you may have read about in our previous blog, Upwell collaborated with tag manufacturer, Lotek Wireless Inc., to develop prototype micro-satellite tags weighing just 2.5 grams. The tags will enable Upwell researchers to piece together the various routes juvenile turtles of different species and populations follow as they cross ocean basins for the first time. Once we know where little turtles go as they grow, we can better mobilize the targeted protections they need in the wild. This blog focuses on two of Upwell’s ongoing collaborations in our Lost Years initiative.

Tagging Juvenile Leatherbacks with the Florida Atlantic University (FAU) Marine Lab

FAU Marine Lab Director Dr. Jeanette Wyneken and her team take pride in being the only research facility in the United States that rears juvenile leatherback sea turtles. Leatherbacks are an extremely sensitive species and they require special care, so the FAU Marine Lab has a highly trained team of caregivers who are assigned to feed, clean, observe, and record abnormal or normal behaviors of these special turtles throughout the day.

When the leatherbacks are ready to be released, Upwell and partners give the tags a final test to ensure that all tags are properly transmitting, and then attach the tags in accordance with turtle species and size parameters. At every stage of captive rearing and tagging, the turtles are monitored by a team of researchers and veterinarians to ensure their health and fitness. After the tags are applied, they are observed in captivity to ensure they exhibit natural behaviors like swimming, diving, and feeding.

As part of our ongoing Florida-based research, we are examining the influence of current velocity on initial dispersal trajectories of juvenile leatherbacks and loggerheads within the Gulf Stream. When the turtles are released into the ocean, a member of the team (wearing snorkel gear) is assigned to each tagged turtle and tasked with observing its behavior in open water. When we are accompanied by a videographer using SCUBA, the snorkeler is also tasked with monitoring the position and safety of the diver, who, in turn, is recording the initial post-release movements and behaviors of the tagged turtles. Thanks to the innovative attachment technique designed by FAU Marine Lab Director Dr. Jeanette Wyneken (publication forthcoming) the tags will fall off the turtle's carapaces as they grow.

So far, the longest transmission duration of a micro-satellite tag on a juvenile leatherback is 31 days. (We hypothesize that the rapid growth of early-stage leatherbacks may result in faster tag-shedding and, therefore, shorter tracking durations as compared to other species.)

This is a novel study; our research with FAU is the first time leatherbacks have been tagged at this early life stage. We aim to collect data across multiple seasons and continue to refine the tag design to extend transmission durations.

In our most recent deployments we have found that these little leatherbacks (< 10cm) routinely dive to depths of up to 80 meters! Our findings have proven incredibly informative as we work to chart the dispersal trajectories of juvenile turtles. The dive data has encouraged us to consider subsurface current influences in our dispersal modeling.

Below you can see a map showing where sea turtles from previous releases have gone. The analysis we have done so far corroborates our hypotheses that little leatherbacks use both currents and active swimming movements to find safe and productive waters as they grow.

Tagging Juvenile Loggerheads with the COSTA Project, Aquário do Porto Pim, and Okeanos Center at the University of the Azores

Dr. Archie Carr, who is credited with coining the term the Lost Years, theorized that juvenile loggerheads in the Azores were arriving from nesting beaches in Florida. But, what are they doing in the Azores? And when do they leave and where do they go next?

Since 2021, Upwell has partnered with the COSTA Project, Aquário do Porto Pim, and Okeanos Center at the University of the Azores to tag juvenile loggerheads to try and answer these questions.

The loggerheads tagged in the Azores are estimated to be between six months and 2 years old. While some of the turtles are rescued and brought to the aquarium for rehabilitation, others are collected through partnerships with local fishers and whale watch companies. Before tagging, the turtles are cared for at the Porto Pim aquarium, where they also play an important role in education and outreach with the local community. Releasing both wild-caught and rehabilitated turtles with satellite tags enables the aquarium to assess the success of the rehabilitation practices used.

The COSTA Project’s Coordinator, Dr. Frederic Vandeperre reflects, “The first thing we learned is that it is possible to take these little turtles, and that's already a huge step forward in our research because it is just something that was never done before at this scale. Now we know how we can improve and how we can better structure our experimental design and target questions more clearly and more precisely.”

Upwell aims to identify important habitat hotspots for juvenile loggerheads as part of this collaborative research. The open ocean habitat around the Azores is not thought to be a highly productive environment for young loggerheads. This research helps us learn more about how they are finding food, avoiding predators, and optimizing growth during their long oceanic stage.

So far, Upwell’s longest transmission period recorded by a micro-satellite tag is 192 days. That tag was deployed on a juvenile loggerhead inhabiting cooler waters, which scientists hypothesize may slow rates of growth. In the graphic below, you can see how turtles from our most recent release in June of 2023 fanned out around the islands, with many heading north over the course of the tracking period.

Mobilizing the Data

After each deployment, Upwell works closely with the tag engineers at Lotek and physical oceanographers at Mercator Ocean International to refine and improve the tags performance. In addition to our ongoing partnerships in Florida and the Azores, we have deployed the tags on green sea turtles in the Cayman Islands and Kemp’s ridleys in Georgia. We are currently building partnerships on the African continent to track juvenile turtles released from the island nation of Cape Verde, and from South Africa’s Atlantic Coast

Each tag deployed and each dataset analyzed provides another piece to the Lost Years puzzle. We are fitting the pieces together with our collaborators at Mercator Ocean International, using the Sea Turtle Active Movement Model (STAMM) developed by Drs. Maxime Lalire and Phillipe Gaspar. The model enables Upwell to examine potential movement trajectories and highlight potential “hatchling highways” that are deserving of protection, for example by limiting fishing gear types, reducing vessel speed limits, or prioritizing the cleanup of plastics.

Tag derived data can be applied to improve tag performance and refine programming that optimizes detection of satellite transmissions based on prevailing field conditions. We hope that our ongoing research will yield enhanced tag performance, extended battery lifetimes, improved data compression, and increases in sensory capabilities and data resolution.

Following juvenile turtles at sea helps Upwell shed light on the important nursery habitats and migration corridors endangered sea turtle species use during their lost years. This kind of data helps to inform effective conservation strategies, and is essential to our efforts to mitigate human-related threats and better protect early stage juvenile turtles during this vulnerable period. It is said that only 1 of every 1,000 sea turtle hatchlings reaches adulthood, but Upwell seeks to improve the odds for tiny turtles!