DIAMOND LAKE, Ore. (AP) - With Diamond Lake free of the invasive tui chub, fishermen say the trout they are catching are fatter and longer than they have been in decades.
     
It is the first time in 15 years the lake has been free of the tui chub, often used illegally as a bait fish. Trout fingerlings stocked last spring have leaped to the top of the food chain.
     
"They had just tremendous growth this year," said Laura Jackson, acting fisheries biologist for the Oregon Department of Fish and Wildlife's Umpqua District.
     
Not since the 1970s have fingerlings shown up in such sizes, averaging 12 inches long, in the ODFWs annual Oct. 31 end-of-season survey.
     
Between 1992, when tui chub first reappeared in the lake, and 2006, when more than 100 million were eradicated by a massive rotenone poisoning program, fingerling trout grew at a rate slower than they had since 1960.
     
The tui chub proliferation had destroyed the food chain in the popular lake. The chub devoured bugs and microorganisms and fed algae blooms with their waste, destroying much of the lake's recreational value.
     
Other than worms and nightcrawlers, live bait is banned in Oregon.
     
Tui chub are native of the Klamath Basin. Biologists say they believe they were carried from there to Diamond Lake as bait.
     
In the 14 months since the massive poisoning, which killed all fish in the lake, samples have turned up more than 200 pounds of bugs and small animals for every acre of lake bottom. In 2006, before the rotenone treatment, samples turned up just six pounds per acre.
     
It is the second time rotenone has been used to wipe the chub from the lake.
     
"It just goes to show how well the lake has rebounded," Jackson said, since there weren't millions of chub to graze everything off.
     
Rick Rockholt, events coordinator at Diamond Lake Resort, said midge and mayflies returned this summer in swarms thicker than he can remember and that the shoreline was chock full of snails, all of which trout eat. "They were stuffed full of bugs," Rockholt said.
     
The number of fishermen visiting the lake this year nearly tripled to 63,000.
     
Rockholt said it will take time for the lake to produce trophy-size fish and attract more than 100,000 fishermen each year, as in the 1960s and 70s.
     
But he says the fish are on pace.
    
"They're just pigs," Rockholt said.

(Copyright 2007 by The Associated Press.  All Rights Reserved.)