A new study provides the clearest evidence yet that blacktip sharks (Carcharhinus obscurus) prey on grey seals off Nantucket. Researchers from the Atlantic White Shark Conservancy, New England Aquarium, and the Massachusetts Division of Marine Fisheries documented an aerial image for the first time showing the killing and consumption of a seal. A finding that enhances understanding of the species and its role in the coastal ecosystem of Massachusetts.
From assumption to confirmation
As early as July 2023, photos and videos of seal predation at Great Point circulated. Initially, the attackers were thought to be great white sharks, but later analyses identified them as blacktip sharks. Previous evidence (such as a single stomach content find from South Africa) was considered a scavenging scenario rather than active hunting behaviour. The now-published study in Environmental Biology of Fishes confirms: blacktip sharks actively hunt seals.
“These observations change our view of the blacktip shark’s feeding ecology – and the interactions between sharks and seals off Massachusetts,” says study leader Megan Winton (AWSC).
Ecological return of old relationships
The researchers do not believe this is a new behaviour. Rather, the findings suggest that predator-prey relationships interrupted for decades are returning as shark and seal populations recover. When marine mammal and shark protections took effect in the 1990s, populations began to grow. Science is now documenting behavioural patterns that were likely common historically but could hardly be observed after the population collapse.
“It is quite possible that this relationship was historically significant – and we may see more such ecological surprises in the future,” says Winton.
Significance for management and safety
The blacktip shark is globally classified as endangered; its populations suffered greatly in the 20th century but are now showing signs of recovery. The results provide starting points for conservation and coastal management: as apex predators return to historical habitats, they influence food chains, fisheries, and beach activities. The researchers also emphasise the value of citizen science: it was public reports that first drew attention to the hunting scenes.
“The return of recovering shark populations can significantly shape coastal ecosystems – with implications for wildlife management and public safety,” says co-author Gregory Skomal (MA DMF).
In summary, the study strengthens the evidence for effective conservation policies and highlights the importance of continuous monitoring, education, and public engagement.
