New Study Reveals Dusky Sharks Preying on Seals for the First Time off the coast of Nantucket
Chatham, Mass. – (August 27th, 2025) – The Atlantic White Shark Conservancy (AWSC) announced today a study published in the scientific journal Environmental Biology of Fishes that documents the first direct observations of dusky sharks preying on seals. In the study, a team of scientists from the Atlantic White Shark Conservancy, the New England Aquarium, and the Massachusetts Division of Marine Fisheries report the first ever aerial footage of dusky sharks killing and consuming a gray seal in the waters off Nantucket, Massachusetts.
In July 2023, multiple shark attacks on seals were reported off the coast of Great Point Coskata-Coatue Wildlife Refuge by beachgoers and boaters. Although initial reports attributed these attacks to white sharks, which have increased in abundance in Massachusetts state waters over the past fifteen years, detailed analysis of photographs and video footage confirmed they were dusky sharks. In response to these reports, the team of researchers conducted drone surveys and captured unprecedented footage of a large dusky shark killing and consuming a gray seal in shallow water. Prior to this observation, dusky sharks were not known to prey on seals, but it seems likely they are resuming a historically important ecological role as populations of sharks and seals along the east coast of the US rebound in response to protective legislation.
“Though the observations we’re reporting are preliminary, they have changed our understanding of the feeding ecology of dusky sharks, which are considered endangered on a global scale, as well as predatory interactions between sharks and seals in the waters off Massachusetts,” said Dr. Megan Winton, senior scientist at the Atlantic White Shark Conservancy and lead author of the study. “This footage provides us valuable insight into understanding the behavior of a shark species that experienced steep population declines in the mid-20th century but now seems to be recovering and reassuming an important ecological role.”
Cape Cod is considered the northern extent of the dusky shark’s range in the summer in the western North Atlantic, but little is known of its distribution and habitat use in this region. Given the lack of long-term data, it is impossible to know for certain if large dusky sharks preyed on gray seals in this area historically. However, it seems likely in light of the observations presented here. “This work opens a new chapter in our understanding of how recovering shark populations in the US Atlantic may influence the ecological structure of coastal ecosystems,” said co-author Dr. Gregory Skomal, Senior Fisheries Biologist at Massachusetts Division of Marine Fisheries and Director of the Massachusetts Shark Research Program. “These incredible observations, a first for this species, raise important questions about how these predators may impact both wildlife management and public safety as they return to their historic habitats.”
The study also highlights the increasing importance of drone technology and public engagement in advancing marine science. Based on the initial footage obtained by eyewitnesses that led to the beach closure, at least three other gray seals were consumed by dusky sharks off Great Point in July of 2023. John Chisholm, Adjunct Scientist at the New England Aquarium and a co-author of the study said, “This discovery illustrates the important roll the public can play as citizen scientists in documenting and reporting shark behavior. Eyewitness reports, paired with new monitoring tools, made it possible to capture rare predator-prey interactions that would otherwise go undocumented.”
To learn more about and to support the Atlantic White Shark Conservancy and their work to advance shark research, conservation, and public safety, please visit atlanticwhiteshark.org.