The whale's bloodied and bruised carcass washed up just north of Long Beach, Washington.
The Royal Canadian Navy had been conducting sonar and small underwater explosive activity off southern Vancouver Island over several days about a week before the whale washed ashore, and there was speculation that navy activity could have killed the orca.
A team of veterinarians and biologists who investigated the whale's death said the navy confirmed explosive activity Feb. 4, 5, and 6. The whale washed ashore Feb. 11.
"No marine mammals were observed during the training activities," said the report released this week by the National Oceanic and Atmospheric Administration in the U.S.
"The activities were too far to the north and downwind of the stranding location to be a consideration."
The team determined the whale did not die in Canadian waters, but more likely near the mouth of the Columbia River or further south along the Washington coast.
The whale was killed by blunt trauma to its head, but the cause of those injuries could not be determined, the report said.
The juvenile female, known as L-112, was a member of an endangered orca pod resident in Puget Sound.
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