An endangered whale that washed ashore in Westhampton this week likely died after being hit by a vessel, the Riverhead Foundation for Marine Research and Preservation said Friday.

During the necropsy Friday, "extensive" bleeding and bruising in the muscle was found all around the body of the 32-foot humpback whale, biologists said.

"The traumatic injuries are consistent with a ship strike," said biologist Kim Durham, who led the necropsy. "Vessel strikes are the primary cause of death for endangered large whale species examined in New York."

Otherwise, the male humpback was in good condition, with fish bones in its stomach, showing it had eaten, she said.

The male was already dead Monday when it was spotted floating 18 miles off the Southampton town's shore before beaching in Westhampton the following day, foundation officials said.

Its death was reported to the National Oceanic and Atmospheric Administration Fisheries, the lead federal agency in charge of protecting marine life and managing fisheries.

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Being struck by ships is one of the biggest threats to these mammals, NOAA said on its website. Other threats listed by the federal agency include entanglement in fishing gear and nets, harassment by whale watching vessels and hunting.

Humpback whales migrate from northern waters in the summer to southern waters in the winter and are favored by many whale watchers because of their aerial displays in "breaching" the water and flapping it with their tails or long, pectoral fins, NOAA said.

When born, the calves measure up to 15 feet and adults can grow up to 60 feet and live 50 years.