Internal tagging confirms long-term survivability of rehabilitated sea turtles

Boston Globe

08-03-2025

For the first time, researchers finally have the tools to track these turtles beyond a few months after their release, thanks to a breakthrough application of technology never before used on sea turtles.
In 2021, the aquarium obtained federal permits from the US Fish and Wildlife Service to surgically implant acoustic transmitters in rehabilitated loggerheads. The transmitter, that's battery life ranges from three years for smaller turtles and seven to 10 years for larger ones, allows researchers to track survival and migration patterns. This data was previously unattainable with shorter-lived external tags, which often detached due to natural shell shedding and physical wear.
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'They're basically sending out ultrasonic pings that are uniquely coded to each transmitter. It's kind of like an E-ZPass system—each tag has a unique code that pings, and in this case, the listening station is an acoustic receiver," said Dr. Kara Dodge, a research scientist at the Anderson Cabot Center and a lead on the project.
Fourteen loggerheads that were rehabilitated at the
aquarium's Sea Turtle Hospital in Quincy, Massachusetts, were
tagged and released between 2021 and 2022. Four years of data confirm that not only are these turtles surviving, but they are consistently returning to the waters of southern New England—especially Nantucket Sound, off Cape Cod's south coast.
Monthly loggerhead sea turtle detections from August 2021 to July 2024. Data was derived from New England Aquarium acoustic receiver arrays and institutions participating in data sharing networks from Massachusetts to Florida.
New England Aquarium
These findings have far-reaching implications for better understanding loggerhead migration patterns,
confirming that rehabilitated sea turtles can thrive long-term, proving
that internal acoustic tagging is viable for studying other species, and gathering data that could help shape future conservation policies.
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'This is helping us understand that the turtles are surviving past that first year after they're released. Before, we really didn't have any information beyond a year, so this is huge,' Dodge said.
The permitting process for sea turtle tagging varies based on a species' conservation status—the more endangered the species, the stricter the requirements.
'This was a pilot study, and we specifically chose loggerheads because they are listed as threatened, not critically endangered. Now that we have results, we're applying for permits to expand this work to Kemp's Ridley and green sea turtles,' Dodge said.
The data also highlights the growing ecological importance of New England's coastal waters for sea turtles, which have been straying farther north and staying there longer, likely due to multiple factors, including warming ocean temperatures.
Mary Beth Tims, biologist moved a loggerhead onto the table so that it could be x-rayed at the New England Aquarium's Sea Turtle Hospital.
Jessica Rinaldi/Globe Staff
'New England is really the northern extent of their range, and the reason they come up here is to feast on the abundant shellfish and crabs we have. They're here for the buffet,' Dodge said.
Between November and January, more than 800 turtles stranded on Massachusetts beaches. About 15 years ago, only 100 strandings per winter were common, but the average number has more than quintupled over that time, Dodge said.
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'If we continue to gather data for larger numbers of turtles in New England waters, we will likely have a better understanding of when they are typically present and where they spend their time, both of which may inform future protective measures,' Dodge said.
Nathan Metcalf can be reached at