The one million tui chub running roughshod over Fish Lake's once-proud trout fishery better start watching their dorsal fins, because there's a new predator in town.

Genetically engineered robo-fish called tiger trout are now stalking this High Cascades lake, where they are expected to start feasting on the unwanted chub while growing to epic sizes.

Tiger trout — sterile brook trout-brown trout hybrids — were bred to create an uber-predator that can thrive in waters over-run with invasive fish species such as tui chub.

The Oregon Department of Fish and Wildlife on Wednesday unleashed the first tigers at Fish Lake, the only such stocking ever in Western Oregon.

Last week, Phillips Reservoir in northeast Oregon received a similar stocking to see whether those tigers can put a beating on that lake's population of illegally stocked yellow perch.

These first tiger stockings will anchor a three-year study to see whether these striped demons will live up to their reputations as the new bad boys of water bodies that suffer from alien invaders.

"It's a unique fish for a unique situation," says David Haight, ODFW's assistant Rogue District fish biologist.

"I don't anticipate they'll control the chub population, but they will take advantage of it," Haight says.

With just 1,690 of the 4-inch tigers stocked Wednesday, the effort may seem a bit like marching a group of school kids to take out an army. But they carry the hopes and dreams of Jim Blodgett, whose Fish Lake Resort business suffers from reduced rainbow trout catches and chub-caused blooms of potentially nasty blue-green algae that trigger public-health advisories annually.

Tiger trout grow quickly, and some of them should be around 15 inches next summer if they mirror growth rates seen at lakes outside Oregon. In Washington, tigers have roared up to 11 pounds. The hope here is that anglers will be hungry to bag one of these 10-plus pounders, and Fish Lake will be the only local place to do it.

"We're excited about it," Blodgett says. "I think it'll be a good draw — not just for us, but for the whole area."

The spectre of a new, big quarry to stalk already has perked the interest of Phil Patterson of Ashland.

As he and Sam Campbell of Talent prepped to troll for trout Wednesday at the lake, they took note of the day's fish planting.

"We go wherever the big fish are," Patterson says. "If they were real good-fighting fish, I'd hope we'd make it up here."

While Patterson might some day know what the tug of a tiger feels like, he won't get to test what they taste like.

Both here and at Phillips Reservoir, the tigers will be available to anglers only on a catch-and-release basis — at least until their populations blossom.

"I've never eaten one, but I'd imagine they'd be a good-eating fish," Haight says.

Tui chub are native to nearby Klamath Lake. They first showed up in Fish Lake in the mid-1940s, likely brought as minnows by some angler. They overran the lake in no time, decimating the zooplankton needed by stocked fingerlings to survive and grow.

The lake was poisoned with chemicals five times between 1951 and 1985. Each time, chubs took refuge near many of the lake's underwater springs and survived.

The invaders are such a problem that ODFW quit stocking fingerling trout there in 1997 because they didn't survive. The 8-inch legals stocked there now keep the fishery going, but at a much higher cost.

In 2007, the Forest Service began an aggressive netting program that removed close to a million chub, but it ended this year with the lake still sporting an estimated million chub.

In an effort to find a fish that can feed on the chub, ODFW stocked the lake with excess Rogue River spring chinook. Success has been modest.

So they turned to the tiger.

Oregon received about 50,000 tiger trout eggs from Washington for free and began rearing them earlier this year at Klamath Hatchery. But the tigers are tough to raise and only about 8,000 survived for stocking this fall.

For future stockings, plans are for the Klamath Hatchery to take brook trout from its Wizard Falls Hatchery near Camp Sherman and spawn them with brown trout collected either at Wickiup Reservoir or East Lake, Haight says.

At Fish Lake, biologists will watch closely to see how the fish grow and do creel checks to see how well they contribute to Fish Lake fishing. Biologists will pump the stomachs of tigers they catch to see whether they are, in fact, eating chub.

Tiger trout are a good choice because the sterile fish won't be able to wander off and start a new population of exotics on their own. If the experiment fails, the tiger trout will die off and it's game over.

"By 2013, they should be of a size where they'll be very desirable to catch," Haight says.

By no means are these robo-fish expected to eliminate Fish Lake's chubs. But the tigers could add a new, effective and entertaining way to have better fishing without chemicals.

"Given the costs of chemical treatments these days, it's not very practical to use rotenone anymore," Haight says. "So we need to find ways to provide fisheries with tui chubs in lakes.

"I hope they do well," he says."

Reach reporter Mark Freeman at 541-776-4470, or email