"We were told that we would never get the Willy in the water," said Rudy McCoy, gardener, Newt Gingrich fan and all-round Seattle character who is the creature's chief promoter. "We got the Willy in the water."
The event made for a pleasantly lunatic outing from a Seattle dock - a team of four divers, several crewmen, assorted media and hangers-on, fishing a 16ft fibreglass killer whale out of the Pacific, whose streamlined shape had more in common with a nuclear submarine than an Orca. Originally built by a Scottish fish farmer, Fake Willy was shipped to Seattle in an attempt to scare off Californian sea-lions gorging on nearby coastal salmon runs.
After a month of trials, whether he has succeeded depends on who you listen to. Mr McCoy and his supporters, who enlisted the help of a local rock radio station to raise the $6,000 (pounds 3,700) to pay his passage, say two sea-lions who recently encountered him displayed a classic "fright response" - surfacing, splashing their heads and slapping their tail flippers. Sceptics might say it was actually sea-lion-speak for a good laugh.
Though dozens of Orcas are known to live off the north-west American coast, they have almost never been known to attack fellow mammals. One diver said he had seen sea-lions swimming 20ft from Willy, just minutes after he was submerged in the water. "Unfortunately they aren't that stupid," said Shad Stovall. "I'd just shoot them."
The problem started more than 10 years ago, when a sea-lion later named Herschel was first spotted near the locks that separate the fresh waters of Lake Washington from the sea. It is there that steelhead trout, technically a breed of salmon, and other fish congregate before making the journey inland to spawn. So easy are the pickings that large numbers of sea-lions have stopped migrating south in the winter - like many other Californian emigres on shore, who are frequently blamed for crime, traffic and overcrowding in the capital of the US north-west, a growing group of young males has elected to stay.
"All of these guys are basically horny teenagers," said Brian Gorman, a spokesman for the National Marine Fisheries Service. Shut out of breeding in California, where larger males guard harems of 10 to 50 females, they have nothing else to do but hang out in Puget Sound. Mostly they eat: up to 40lb of fish a day. From about 2,000 a day, the number of adult steelhead spotted swimming up fish ladders round the locks has dropped to around 100.
The fisheries service has spent more than $1m over 10 years trying to drive them off. But foul-tasting bait, rubber bullets, trapping and even loud country music played under water have failed to dislodge the gluttonous mammals sitting on a constant supply of free food. The latest acoustic device, slung across the locks, emits an electronic chirp likened to an 800lb cricket.
Other methods have been tried - six sea-lions were captured and sent by truck to California, but they returned within weeks. One was put up in a Seattle zoo for the duration of the salmon run and others resettled in a Florida marine park, but new homes cannot be found for all the miscreants. A year ago frustrated fisheries officials finally recommended "permanent removal".
Mr McCoy and his friends hope Fake Willy, whose name is borrowed from the film Free Willy, will help remove the need to trap and kill the sea- lions, but marine biologists have scorned the experiment. "It's been extremely positive," Mr McCoy insisted after the boat trip, though he admitted: "We've had critics say it's a waste of time and a waste of money, just shoot the pesky critters."
The jury is still out on Seattle's voracious sea-lions, but it may soon return with a more final solution than Fake Willy.