New Study Finds Cape Cod & Islands are a Hotbed for Leatherback Sea Turtle Vessel Strike Fatalities

A recently released study published in Biological Conservation identified the waters off Cape Cod as an especially deadly area for leatherback sea turtles which are fatally struck by boats and other watercraft.

The article, “Navigating danger: Watercraft-related mortality of sea turtles in the United States Atlantic and Gulf coastal waters,” is a broadscale assessment of four species of federally protected sea turtles – Leatherback, Kemp’s ridley, Green, and Loggerheads – that documents clusters of turtles impacted by vessel strikes in order to prioritize conservation efforts. The lead author is Dr. Mariana M.P.B. Fuentes, Professor in the Department of Earth, Ocean, and Atmospheric Science at Florida State University.

Karen Dourdeville, Bob Prescott and Mark Faherty, of Mass Audubon, were among the co-authors on the paper. Other co-authors were members of the National Oceanic and Atmospheric Administration (NOAA) national Sea Turtle Stranding and Salvage Network.

Although most vessel-struck strandings of all four species occur in the waters off Florida, Texas, and Virginia where sea turtles are in the waters year-round, the coast of Massachusetts saw the highest number of strandings of vessel-struck Leatherback turtles. Between 2010 and 2022, 337 Leatherbacks were struck by watercraft along the East and Gulf Coasts. Of those, 88 incidents (26 percent of the total) occurred in Barnstable and Dukes Counties—the highest concentration in the study area. Tragically, 96 percent of the Leatherbacks struck in those counties died.

While Leatherbacks represented the lowest total number of strandings compared to other species, the study found they had the highest proportion of vessel strikes. That is attributed, at least in part, to this being a busy area for recreational and commercial watercraft as well as the propensity of Leatherbacks to swim and feed at or near the surface, increasing the probability of watercraft striking the turtles.

“This is an important study because it means we can better compare stranding numbers for a large geographic area and across four different species to identify stranding trends. Knowing these trends can potentially help us prioritize crucial interventions and boater outreach that could cut down on sea turtle mortality rates,” said Karen, Bob and Mark. “Some years many Leatherbacks remain farther offshore, not spending extended periods feeding in Cape Cod Bay, Nantucket Sound, Vineyard Sound and Buzzards Bay. These lower occurrence trends mirror the total number of strandings. Of special note, however, is that, although the total number of vessel-struck Leatherback strandings may be down in recent years in our local waters, the percentage of stranded Leatherbacks killed by vessel strikes has risen."

Mass Audubon urges boaters to use caution and keep an eye out for Leatherbacks and other sea turtles as they operate in the area, and to report any sightings and/or strandings to our hotline for boaters, seaturtlesightings.org.

Working under a U.S. Fish and Wildlife Service permit, Mass Audubon staff on Cape Cod maintain this sightings website and database, as well as conduct year-round sea turtle rescue, research, stranding response, public outreach, and education. 

To read the entire article, visit https://www.sciencedirect.com/science/article/pii/S000632072500518X.