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Diamond Lake buzz: Trout pig out in post-tui chub era

Mari Brick's eyes pan Diamond Lake's chilly December surface, leaving her to wonder just how big of a Christmas party the trout are throwing themselves below.

With more bugs to feast upon per acre than a Fear Factor dunk tank, the trout have been busy packing on the pounds since they were released in the lake cleansed of 100 million tui chubs by a massive poisoning effort in September 2006.

By the time the spring fishing season returns to this southeastern Douglas County lake, nothing with a fin on should be shy of a foot in length.

"I think it's safe to say they should be 12 inches by then," says Brick, a biologist with the state's Diamond Lake Restoration Project. "They're averaging 10.9 inches now and, historically, they've grown an average of one inch over winter.

"So, that's what we'd expect," Brick says. "But this lake continues to break all our expectations."

The Oregon Department of Fish and Wildlife this week wraps up its final analysis of the recovery of the trout fishing and the lake's ecology in 2007, the first season after the rotenone treatment.

Under a $5.6 million program, technicians applied rotenone that killed off everything in the lake, then began a conservative fish-stocking and aggressive monitoring program that saw an explosion of fish sizes and fishing success at what used to be Oregon's most popular trout lake.

More than 72,000 angler trips there led to the catching and keeping of almost 87,000 stocked trout up to 6 pounds, with catch rates at 1.3 fish per stay on the water.

Anglers collectively spent more than $2.7 million — about three times what an environmental study estimated in 2000 for this past season, which ended Oct. 31.

The catches, trips and revenue all far out-stripped even next year's goals and inched close to historical levels of 100,000 angler trips a season.

Peggy and Gary Shontz are part of those statistics, fishing at the lake where they spent their honeymoon in the family's cabin 35 years ago. They were so pleased with the lake's turnaround that they bought the family cabin this year — something they would not have done had the chubs been around.

"It's so nice to see the fishing coming back," says Gary Shontz, of Rogue River. "It's nice to see this whole thing have a happy ending. It's positive for the community."

Despite all the talk of quantity of fishing effort and catch, the quality of the fish has created the biggest buzz and led to longer head-scratches by biologists like Brick who didn't dare expect to see such success.

The lake's benthic — or insect — load ballooned from near nothing to more than 200 pounds per acre even though the trout were acting like complete bug-gluttons.

"They ate everything they could fit in their mouths, but it didn't hurt the growth of zooplankton and insects," Brick says. "It's like they didn't even touch them."

Heading into December, the smallest trout there have grown obese enough to qualify for disability placards, packing on an average of almost 2 inches a month since they were stocked last spring while averaging just over 3 inches long.

That 10.9-inch average length might also be close to the average width. They're shaped as if you could throw a spiral with them.

"It used to be they had huge heads and itty-bitty bodies," Brick says. "Now, it's itty-bitty heads and enormous bodies."

The reason both fish and insects were able to explode simultaneously is that the first year's stocking effort was relatively light compared to the available food.

It's analogous to having all the steam tables at Hometown Buffet stocked with enough food to feed 100 people around the clock, "but only 25 of them got a pass to get in," Brick says.

That will change next year.

The ODFW plans to stock about 75,000 trout ranging from 8 inches to 5 pounds — just like last season. However, the stocking of fingerling will double to 200,000, creating a multi-tier fishery envisioned before the rotenone treatment.

"I can't wait until next year," says Rick Rockholt, the events coordinator at Diamond Lake Resort, who has spent the past 25 years there. "Those fish are pigs. Absolute pigs. I'm so tickled I can hardly stand myself."

Reach reporter Mark Freeman at 776-4470, or e-mail mfreeman@mailtribune.com.

Biologist Mari Brick lands a large rainbow trout in Diamond Lake.