SEATTLE — Severe scars on a gray whale found dead at Bremerton indicate a killer whale attack years ago left it too weak to complete this year’s migration from Alaska to Mexico, a biologist said.
Looking for food in Puget Sound, the whale was able to find only woody debris in the sediments, said John Calambokidis of Cascadia Research, who pulled handfuls of sticks and bark out of its stomach during the necropsy.
The 29-foot immature male looked emaciated, its layer of blubber thin.
“It also had very serious older injuries suggesting things that may have led to it being in poor health,” Calambokidis said Friday. “It could have been weakened originally by being attacked by orcas.”
Killer whale scars are visible on a significant number of live animals, he said. The scars on the Bremerton whale were more extensive.
The whale was found dead Jan. 19 near the Puget Sound Naval Shipyard. The Navy towed it to Manchester for a necropsy examination Jan. 23. The examination was conducted by biologists with the Washington Fish and Wildlife Department and Olympia-based Cascadia Research with the assistance of the Navy and National Oceanic and Atmospheric Administration.
The whale was likely attacked a couple of years ago when it was a calf on the northbound migration from the breeding waters of Mexico to waters off Alaska where gray whales feed, Calambokidis said. There were healed teeth-rake marks on the pectoral flippers, the rear of the body and on the flukes, the tips of which were gone.
“That may have prevented this animal from being able to fully thrive and make the best of it,” he said.
The whale apparently joined this winter’s southern migration but only made it as far as Puget Sound because of ill health.
“It may have even been in a not fully competent state to navigate its way south,” Calambokidis said.
The whale was sighted several times in Puget Sound, including Jan. 15 in the Foss Waterway at Tacoma, where it apparently was looking for food. This is fairly common in gray whales that are not doing well.
“They’re going through the motion of feeding even as they’ve lost the ability to find productive feeding grounds,” he said.
Gray whales are sometimes able to feed on Puget Sound shrimp, especially off Whidbey Island. But there was no sign of them in the whale’s stomach contents, Calambokidis said.
This was the first dead whale found this year in Puget Sound. About six gray whales typically die each year in Washington waters. There were three deaths in 2012, one of which was in Puget Sound, Cascadia Research said. Gray whale strandings are also common in the spring when the animals migrate north to Alaskan waters.
An exact cause of death has not been determined for the Bremerton whale. Tests on tissues and organ samples are pending. The Navy towed the carcass to deep water and sunk it.
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