Jason Hussa, a volunteer with the Oregon Marine Mammal Stranding Network, pulls aside a piece of blubber from the whale.

SEASIDE — The dead 24-foot humpback whale that washed ashore on the north end of Seaside’s beach Sunday caused quite a stir.

A couple of dozen onlookers stopped to watch Tuesday as a team of marine experts from Portland State University and Oregon Marine Mammal Stranding Network volunteers performed a necropsy on the animal, which had been moved slightly inland and north on the beach. Some came to town specifically to see the whale.

The team collected biological samples that will be used to help determine a cause of death. If there are no “smoking guns,” such as bullet holes or something stuck in the mammal’s throat, then it can take days or weeks to determine a cause of death, said Keith Chandler, the general manager of Seaside Aquarium.

It was clear the animal did not die from old age, as it was only about a year old, Chandler said. He said it is not unusual to see a whale wash ashore on the North Coast, but they tend to be gray whales. Humpbacks are rare — Chandler said he has only see a few in his 20 years with the stranding network — but the species was spotted in nearby waters recently.

“There were a few humpbacks hanging out in the mouth of the Columbia River last year,” he said. “They are usually further offshore. It could have died offshore and with the storm, washed in.”

The whale was one of at least five cetaceans to wash up in the area in three days. A harbor porpoise and two striped dolphins were found Saturday. One dolphin was found in Cannon Beach and the other in Ocean Park, Washington. A third striped dolphin washed ashore in Seaside Monday. Chandler said it is “quite unusual to get them all together,” especially the striped dolphins.

The Ocean Park dolphin showed signs of being entangled in a net and had a hole in its tail that appeared to be from a gaff, Chandler said. The dolphin from Seaside had a similar hole in the same area, but it had not undergone a necropsy by Tuesday. Chandler said it could be a single event — getting caught in the net — that caused the unusual occurrence of killing multiple dolphins at once. If a single event is the cause of death, Chandler said, then “we know it’s just an accident,” as opposed to persistent conditions impacting a species, like disease.

City crews planned to bury the whale at the beach by Wednesday morning.