A Novel Surgical Tagging Approach Shows Promise for Long-Term Detections

In 2021 and 2022, our Animal Health and Rescue and Rehabilitation teams and researchers from our Anderson Cabot Center for Ocean Life took a novel approach to their acoustic telemetry research by surgically implanting acoustic tags in fourteen rehabilitated loggerhead sea turtles from our Sea Turtle Hospital. The tags—which act like an “EZ-Pass of the sea”—send a unique ultrasonic ping to receivers throughout the ocean, which are part of collaborative telemetry networks covering waters from Canada to the Caribbean. When the turtle swims within range of a receiver, it sends a “ping,” giving researchers data about a tagged animal’s survival and movements.

Researchers hypothesized that the surgically implanted tags would provide a longer duration of detection compared to external transmitters, which are susceptible to biofouling, damage, or simply falling off the turtle after a period of time. In 2023, when we last shared updates from the project, the data showed promise. Almost two years later, we have heard from every tagged turtle, with 400+ days of detection data for most and multi-year data for several turtles.

“It’s like Christmas morning every time we receive a new set of data,” said Dr. Charles Innis, one of the researchers on the study. While the batteries of some of the 2021 tags may soon expire, the team expects to continue receiving data from other tags that may last an additional five years—proving not only their hypothesis of improved detection duration but also showing that rehabilitated turtles continue to do well several years after their release.

“Thanks to satellite tag data, we know that the vast majority of our rehabilitated turtles are surviving in the wild and showing behavior typical of their species,” said Dr. Kara Dodge, who is also leading this study. “However, that data has been time-limited to around six months to a year. The acoustic transmitters are telling us these turtles can survive beyond that first year, and they are showing up in well-established feeding areas.”

Researchers are also learning new information about the turtles’ behaviors thanks to the extended longevity of the tags. “I have been surprised by how many loggerheads returned to New England one year later—and even two years later for one individual!” said Dodge. Aside from the rare cases of turtles that have re-stranded on Cape Cod in subsequent years, not much is known about foraging site fidelity to New England waters. “It will be interesting to see if this is specific to loggerheads or if it’s also true for Kemp’s ridley and green sea turtles,” Dodge added.

The team is expecting to receive data from most of the tags through 2025; a select few with larger batteries could potentially return data through 2032. They’re also seeking permission to duplicate this work on other species of sea turtles in the hope that the longer-lasting tags can provide more insights into turtles’ behavior that can’t be gained through other types of tags. “For some turtles that have been double-tagged with internal acoustic and external satellite tags, we’ve been able to determine satellite tag failures,” Dodge said. “Without the internal acoustic transmitter, that turtle’s fate would have been unknown.”

Eventually, this long-term data could be used to inform future protections for sea turtles in New England waters. “We know from strandings that turtles are using this area annually,” Dodge said, “but the lack of data for these species in New England means it’s often left out of consideration as a critical habitat.” It takes time to build the data sets that inform protections and habitat management practices. “That’s exactly what we’re doing with our satellite and acoustic tagging work,” Dodge said.

Follow Our Sea Turtle Tracker

Explore our interactive map of sea turtles that have been satellite-tagged by the New England Aquarium and our Anderson Cabot Center for Ocean Life and follow their journeys!

Thanks to the ACT Network and the owners of the arrays who provided data and make this work possible: the Atlantic White Shark Conservancy and Massachusetts Division of Marine Fisheries; the Atlantic Shark Institute; Equinor Wind, LLC; Orsted Wind, LLC; SouthCoast Wind, LLC; NOAA Fisheries Northeast Fisheries Science Center; Rhode Island Department of Environmental Management Division of Marine Fisheries; Connecticut Department of Energy & Environmental Protection; Stony Brook University; New Jersey Department of Environmental Protection; Rutgers University; Monmouth University; NOAA Chesapeake Bay Office; Benjamin Marsaly; University of Maryland Center for Environmental Science; The Nature Conservancy; the Applied Ecology Lab at North Carolina State University – Center for Marine Sciences & Technology; South Carolina Department of Natural Resources; Georgia Department of Natural Resources; and Florida Fish and Wildlife Commission.