SEATTLE -- Luna, the juvenile killer whale from Washington state waters who got lost in Canada's Nootka Sound five years ago, apparently died Friday when he was accidentally struck by a tugboat propeller, Canadian authorities said.

Luna, known to scientists as L-98 and a member of one of Washington's three resident orca pods, or family groups, wandered into Nootka Sound on the west side of Vancouver Island in 2001 and stayed, worrying activists and annoying boaters and seaplane pilots with his friendly curiosity.

We don't know 100 percent but we do believe it's Luna," said spokeswoman Lara Sloan with Canada's Department of Fisheries and Oceans.

Transient killer whales, which range along the coast preying on seals and other marine mammals, occasionally come through the long, twisty sound, but tend to avoid human traffic.

The dangerously friendly Luna was part of the region's "resident population," which spends much of the year in U.S. and Canadian inland waters. They live and hunt in family groups and mostly eat fish, especially salmon,

The 1,700-horsepower seagoing tug had pulled into sheltered waters near Conception Point to escape rough weather in the Pacific. Luna, known to enjoy playing in boat wakes, "was swimming under the vessel and was hit by a propeller," Sloan said.

"It was a really big tugboat -- 104 feet," she said.

The vessel was idling when Luna approached.

"Luna came over as he does and was interacting -- disappearing under the hull and so on. ... He must have gotten drawn into the propeller," said government research scientist and orca expert John Ford.

The tug's big propeller, contained in a cylinder, "generates a lot of current. ... It would have been a sudden death."

"The skipper is reported to be greatly distressed. He called the coast guard immediately after it happened," Sloan said from agency offices in Vancouver, British Columbia. "A lot of people here are pretty shocked and saddened."

"It was one of our fears about what might happen to Luna," Ford said. "Of course he's been engaging in these risky interactions with boats for several years now."

Luna likely was not familiar with the size and power of this vessel. While the carcass was not immediately recovered, "it seems almost certain to me that this is indeed Luna," Ford said. "And it's almost certain it was fatal."

Ford last saw Luna in January, when Ford visited the sound in a 200-foot research boat. "He came over. He was always curious."

"It's a very tragic ending," he said.

Luna was about 6 years old. Orca life stages roughly parallel those of humans, so he was the killer-whale equivalent of a young child.

"The whale has always flirted with this kind of danger," said Fred Felleman of Ocean Advocates in Seattle, who had pressed for more efforts to reunite Luna with his family. "It was like that old children's cartoon, 'Are you my mother?' Orcas are very social animals, and this was the only way to get his social needs met."

Felleman called on authorities to recover Luna's remains and learn what they could about him. "Failure to do so would be a huge missed research opportunity, as indeed his whole life had been," he said.

Lonely and apparently seeking contact, the whale had damaged and disabled several boats over the years. Lately, he had been gathering scars from increasingly frequent close calls with propellers, but apparently no serious injuries.

Canada tried in 2004 to reunite him with his pod in the Strait of Juan de Fuca, which separates Washington state from Vancouver Island.

That effort was scrapped when local Indians lured Luna away from the net pen intended to snare him. The Mowachaht/Muchalaht First Nation believed the orca embodied the spirit of their dead chief, Ambrose Maquinna, and did not want him forcibly removed.

Luna's advocates had hoped he might reunite naturally with his family as they passed the mouth of Nootka Sound.

Members of L-pod, Luna's relatives who spend summers chasing salmon off Washington state's San Juan Islands, occasionally travel on the west side of the island. But even the most ardent supporters of a natural reunion agreed it would take a lot of luck for Luna and L-pod to find each other.

In 2002, the U.S. and Canadian governments successfully reunited a Canadian orca, A-73 or Springer, with her family after her mother died and she wandered into busy Puget Sound. She had only been separated from Canada's A-pod for a period of months.

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On the Net:

Canada's Department of Fisheries and Oceans, http://www.pac.dfo-mpo.gc.ca

National Marine Fisheries Service: http://www.nwr.noaa.gov

Orca Conservancy: http://www.orcaconservancy.org/