Boat-strike likely killed humpback whale that washed ashore near Manzanita

A necropsy completed on a dead humpback whale that washed ashore earlier this week south of Manzanita indicates the animal likely died after being struck by a boat.

“The team found bleeding, bruising and swelling along the right side of the whale’s head and sides,” NOAA reported in a news release. “The injuries suggest a blunt force impact such as a vessel strike.”

Vessel strikes are one of the more common causes of death for humpback whales stranded on the West Coast, according to NOAA Fisheries’ most recent estimate of whale population numbers. NOAA estimates some 5,000 humpback whales live off the coasts of Oregon, Washington and California – and their numbers are growing.

The 34-foot juvenile male humpback was first reported floating off the coast on Sunday, May 26, near Nehalem Bay State Park. The whale carcass washed ashore Monday, when samples were first taken. A full necropsy, led by Portland State University, was completed Thursday. Staff from Oregon State Parks, Oregon Department of Fish and Wildlife, U.S. Fish and Wildlife Service, Cascadia Research Collective and Seaside Aquarium also assisted with the necropsy.

Dead whales are often left to decay on the beach, as the carcasses provide food for eagles and other scavengers.

The public is urged to avoid the area where the whale washed ashore to avoid further disturbing threatened western snowy plovers that nest nearby. Dogs and bicycles are prohibited in the area, which is a more remote part of the state park.

To report a dead, injured, or stranded marine mammal along the West Coast, the public can call the West Coast Region Stranding Hotline at (866) 767-6114.