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Wednesday, March 5, 2003 - Page updated at 12:00 AM

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Killer whales head out to sea

The Associated Press

The transient killer whales that spent an unprecedented eight weeks in Washington's Hood Canal, gorging themselves on the local harbor-seal population, have headed back out to sea.

Four of the orcas left early Monday, and the remaining seven left a few hours later, said marine-mammal biologist Steve Jeffries with the state Department of Fish and Wildlife.

Hood Canal bridge supervisor Dean Crawford saw the larger group swim north and dive under the floating bridge, which crosses the natural channel to link the Olympic and Kitsap peninsulas. About two dozen harbor seals and a couple of sea lions were hanging out on the south side of the bridge as the orcas went by and took one seal, he said.

After clearing the bridge, Crawford said, "they made a beeline for the mouth of the canal," probably bound for the Strait of Juan de Fuca and out to the Pacific Ocean.

Jeffries said the move likely slashed the local harbor-seal population, estimated at 1,200 to 1,500 in early January.

To meet metabolic requirements, the average killer whale probably needs one to two seals a day, Jeffries said. If the whales averaged just one seal daily, the take over two months would have been more than 600 seals. And the two big male orcas "probably needed two to three seals a day," he said.

He said the Pacific Coast has no shortage of pinnipeds — seals, sea lions and walruses — especially since the Marine Mammal Protection Act halted hunting by humans.

Over 30 years, researchers say they've never heard of transients staying in one place more than two weeks. In Southeast Alaska, said Marilyn Dahlheim of the National Marine Mammal Laboratory, they keep moving — presumably because their prey become wary after a time.

Jeffries figures they found their way into Hood Canal "more or less by accident" while cruising the coast for prey and monitoring the spring gray-whale migration north to Alaska from Mexico.

Grays Harbor and Willapa Bay on Washington's Pacific Coast have plenty of seals, but they also have "a maze of shallow sandbars and channels that change seasonably" and make them difficult places to hunt.

The deep waters of Hood Canal, about 100 miles inland from the ocean, make it "a perfect place" for orcas chasing seals.

So-called transient orcas live along the coast and feed mostly on marine mammals. The Pacific Northwest's orcas, which spend summers in the region's inland waters around the San Juan Islands and off Canada's Vancouver Island, feed mostly on fish. A third population, called offshores, is thought to mix mammals and fish.

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