Tiger trout -- a cross between brown and brook trout -- are making their reputation as bare-knuckle brawlers and a hot new challenge for Washington anglers Photo courtesy of Terry W. Sheely

On that hot July day, fishing in a coldwater bowl between crackling sagebrush and black volcanic rock, Dennis Werlau Jr. set the hook on a beautiful 6.26-pound Lenice Lake trophy trout and rewrote history.

The fish that Werlau caught on July 6, 2006 was tough, aggressive, with the strange vermiculated markings of both Salmo trutta and Salvelinus fontinalis. It was a brook and brown trout mix -- a tiger trout!

Offspring of female browns and male brookies, tiger trout are a genetic mix -- a sterile hybrid that is neither trout nor char, but a combination of both. And it’s staking out a reputation as a bare-knuckle brawler and a hot new challenge for Washington State anglers.

Werlau’s trophy stands as the certified state record. But fish managers will be surprised if that record isn’t shattered several times in the next fishing season. Tigers are thought to be a lot more aggressive than either of their parents -- an endearing quality for sportfishermen.

Growth rates depend on the fertility of the host lake. But if there’s not too much competition for food from other species, tigers stocked as fingerlings will reach 14 to 15 inches by their second year.

Tiger trout are strikingly colored. Light brown and gold with ribbons of vermiculations -- or worm tracks -- cover their backs and sides. Their bellies are yellow-orange.

How big will tiger trout eventually grow? That’s one of the great mysteries of this crossbreeding that biologists hope to answer as the hybrid stockings spread across the state.

Because the fish are sterile, they put no energy into reproductive behavior and channel it all into fast growth and long lives. The larger fish that result could develop into a fishery similar to the state’s popular triploid trophy trout program.

If there’s a shadow on this project, it’s that as predators, tiger trout may be just too efficient for the good of rainbow fisheries.

Jeff Korth, a Washington Department of Fish and Wildlife biologist, is spearheading the state’s tiger trout infusion. He said that in some lakes, tigers are too much of a good thing, if eating your neighbors is a bad thing.

“If tiger trout numbers get too high in a fingerling-stocked trout lake, they can put a damper on fingerling survival,” said Korth.

The fish biologist said he hasn’t yet seen evidence of competition because tigers are stocked at relatively low numbers compared to rainbows.

The Evergreen State’s first tigers were raised in the Department of Fish and Wildlife’s hatchery at Ford in eastern Washington. In 2001, they were planted in 16 select Grant County waters that already held either browns or brookies. That first plant was an experiment, and included only about 40,000 fish.

Now Korth’s experiment is growing legs and crossing the state, and gathering popularity with every expansion. This year, that original 40,000 stocking confined to the Columbia Basin has jumped to almost 115,000 and has crossed the Cascade Mountains.

Trout waters from Spokane to the west slope of the Cascades are now strongholds for tiger trout. On the east side of the state, the one area not being stocked with tigers is WDFW’s Region 3, which includes lakes on the east slope of the Cascades and a liberal splattering of Columbia River tributaries.

WDFW Yakima fish biologist Jim Cummins said that fish managers in his region worry that the aggressive tigers will have negative impacts on other sportfish species like native trout, char, steelhead and salmon, several of which are already under Endangered Species Act protection.