Scientists find the world's largest turtles in previously unknown foraging grounds.

Reconstructed satellite tracks of leatherbacks tagged from Massachusetts (A) in summer and North Carolina (B) in spring between 2017 and 2022. Locations recorded along the Mid-Atlantic Bight and Southern New England are black boxed and enlarged in (A). In (C) the colors correspond to the latent states predicted by the hidden Markov model: restricted territory exploration with high diving intensity (ARS-H), restricted territory exploration with low diving intensity (ARS- L), wide area search (BAS), and temp. Credit: Frontiers in Marine Science (2024). DOI: 10.3389/fmars.2024.1325139

Leatherback sea turtles, the largest of all living turtles, make extensive migrations that can span several years. They travel from subtropical and tropical nesting sites to temperate foraging areas. Despite decades of tracking efforts, there are still areas—including the northwestern Atlantic—that little is known about turtle migration routes and foraging areas.

Using new and more sophisticated tracking technology, a team of researchers in the US set out to identify migratory corridors and prospects. Areas used by leatherbacks along the east coast of the United States. The results are out. published I Frontiers in Marine Science.

“Using movement-behavior models, we show that leatherbacks migrating along the East Coast of the United States forage in specific areas of the South Atlantic Bight (SAB), from North Carolina to the coastal region extending to the upper Florida Keys; the Mid-Atlantic Bight (MAB), which is the coastal region from Massachusetts to North Carolina; and southern New England (SNE),” said Dr. Mitchell Ryder, a postdoctoral researcher at the University of Miami. “It appears that MAB may hold an important foraging ground for leatherbacks.”

New foraging sites discovered.

To track the turtles, the researchers fixed satellite transmitters in two groups of leatherbacks. The first group was tagged off Massachusetts in the summer, the second off North Carolina in the spring.

Scientists find the world's largest turtles in previously unknown foraging grounds.

Predicted locations of leatherbacks along the southern New England coast in 2018 (n = 4), 2019 (n = 9) and 2022 (n = 8). Colors correspond to the latent states predicted by the hidden Markov model: area-restricted search with high dive intensity (ARS-H), area-limited search with low dive intensity (ARS-L), extensive Area search (BAS), and temp. Credit: Frontiers in Marine Science (2024). DOI: 10.3389/fmars.2024.1325139

Off Massachusetts is a popular foraging area where leatherbacks migrate north after foraging. Tracking them from there allowed researchers to identify secondary forage and colder areas along the continental shelf. Tracking turtles captured from North Carolina enabled them to assess diving and movement behavior on migration routes and to identify subsequent foraging areas. Between 2017 and 2022, 52 leatherbacks were successfully tracked between 15 and 302 days.

The researchers’ results indicate that in addition to foraging areas in the SNE and Nova Scotia, leatherbacks use the SNE, MAB, and SAB regions as migratory corridors and foraging areas. “High utilization of MAB by both groups of leatherbacks is the most important finding of our study. High utilization is largely characterized by inferred foraging behavior,” Ryder said. “To date, several studies have tracked leatherbacks in this region, but we are the first to take it a step further and characterize the behaviors associated with their movement patterns.”

Knowledge for conservation

New knowledge about leatherback movement ecology and foraging areas along the northwest Atlantic shelf is likely to open new doors for future work on leatherbacks in the MAB and SAB, the researchers said. “Now that we understand the main hotspots where foraging is going, we need to focus our attention on those specific areas to apply methods that allow for direct observations,” Ryder explained. . “For this, we need to implement more in situ styles of research such as animal-borne video surveillance.”

Despite their now deep understanding of leatherback movements and foraging, there is still work to do, the researchers said. This includes studying leatherbacks in the SAB, as the region serves the turtles in winter, nests in spring and forages in summer.

The researchers said their findings are also important for the conservation of endangered species. Leatherbacks are vulnerable to bycatch and attacks from fishing vessels. The new findings can be used to highlight important areas for safety and help prevent these accidents. Additionally, the MAB and southern New England are poised to see a large amount of offshore wind farm development and conservationists can use this knowledge to help mitigate impacts on endangered turtles.

More information:
Mitchell J. Ryder et al., Where leatherbacks roam: movement analysis reveals new foraging sites along the northwest Atlantic shelf, Frontiers in Marine Science (2024). DOI: 10.3389/fmars.2024.1325139

Reference: Scientists track world’s largest turtles to previously unknown foraging grounds (2024, February 21) https://phys.org/news/2024-02-scientists-track-world-21 February 21, 2024 Retrieved from largest-turtles.html

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