Dead Sperm Whale Washes Ashore on Nantucket

November 16, 2025: Dead Sperm Whale Washes Ashore

On November 16, NOAA Fisheries stranding network partner Marine Mammal Alliance Nantucket (MMAN) was alerted of a dead whale. It had washed up onto the north shore, near 40th Pole Beach, in Nantucket (island off Cape Cod), Massachusetts. The trained responders documented the whale in the surf zone and determined that it was a large sperm whale, 40-50 feet long, estimated at 104,000 pounds. Sperm whales are the largest of the toothed whales.

Over the course of the week, NOAA Fisheries and MMAN worked closely with officials from the Town of Nantucket and our local stranding network partner, the International Fund for Animal Welfare. First, we asked if they could perform a necropsy (animal autopsy) to assess the animal's overall health and help find out what might have caused or contributed to the whale's death. Second, we discussed what would be done with the whale's body afterwards.

Completing a necropsy on a large, adult whale can be logistically challenging, as it can take dozens of biologists and multiple pieces of heavy equipment. However, the beach where the whale was located could not be reached by the necessary heavy equipment. Teams agreed that moving an animal this large over land to a different necropsy site was not possible. Therefore, we planned a limited necropsy, meaning they would perform as much of the necropsy as they could in place. Municipal officials then assessed their options to dispose of the whale after the necropsy. Due to the high wave action, instead of burying the whale on the beach, we planned to tow the carcass far offshore to naturally decompose.

During stranding events, NOAA Fisheries also attempts to work closely with local Tribal Nations to facilitate cultural practices, as whales can play an important role in their beliefs and culture. At some strandings, Tribes seek to lead ceremonies to honor their beliefs.

November 21, 2025: Necropsy Performed

Early on November 21, biologists from the International Fund for Animal Welfare and New England Aquarium led the examination, measurements, and sampling of the whale. They cut "windows" into specific organs and a large wound on its dorsal surface (back). They used this method so they could tow the whale offshore in one piece. There was also a limited amount of time to access the carcass at low tide. The biologists found most organs to be heavily decomposed, but will send samples of the wound and surrounding tissues to a pathologist for further analysis. No conclusive cause of death can be determined at this time, which is sometimes the case.

Once the necropsy was complete, the towing company took over. The whale was towed about 40 miles east of Cape Cod, to decrease chances that it would wash back onshore. A solar satellite tag was attached so the position of the carcass could be monitored.

How to Help a Stranded Marine Mammal

Many people want to help stranded animals, but only trained responders should approach them. Even if a stranded animal is dead, attempting to touch or move them can be dangerous. We appreciate the many concerned onlookers who remained a safe distance from the whale, giving response teams room to work.

All dolphins, porpoises, and whales are protected by the Marine Mammal Protection Act , and some (including sperm whales) are also listed under the Endangered Species Act. It is illegal to touch, feed, or harm them. The best way to assist these animals, and keep them and yourself safe, is by immediately calling trained and authorized responders and maintaining a 150-foot distance. To report injured, entangled, or dead marine mammals and sea turtles in the Northeast, call NOAA's stranding hotline to be directed to a trained responder in your area: (866) 755-6622.

We are grateful to all partners involved, who made this undertaking possible:

• Marine Mammal Alliance Nantucket
• IFAW
• New England Aquarium
• Town of Nantucket
• United States Coast Guard, Sector Southeast New England
• NOAA Office of Response and Restoration
• NOAA Office of Law Enforcement
• MA Environmental Police
• EPA Region 1
• Private property owner and manager