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Chub net idea gets the hook Biologists say most chubs too small for full eradication By Mark Freeman DIAMOND LAKE � Biologists for years have believed that Diamond Lake�s illegally introduced tui chubs eat like a swarm of grasshoppers, breed like bacteria and can take up space like a St. Bernard in a sleeping bag. On Wednesday, biologists added "skittish" to the long list of undesirable qualities that make chubs the worst of enemies to the lake�s fishermen. The estimated 26 million chubs are so skittish and scattered throughout Diamond Lake that fishing them out with nets does not appear to be a viable alternative to chemical treatment for killing off the invading chubs. A Newport herring fisherman�s three days of experimental chub-netting show that nets can catch the bigger chubs but fall far short of snatching enough chubs to reclaim Diamond Lake for rainbow trout and the anglers who stalk them. "It�s not even going to touch them," says Bob Schoans, a commercial fisherman hired by the Oregon Department of Fish and Wildlife for this week�s four-day netting experiment. "We can�t find them in big enough quantities to catch significant numbers of them. They�re too scattered around here." The experiment, which costs $25,000 and will conclude today, lends more ammunition to those who believe chemicals are the only way to effectively kill off the chubs. If mass netting could remove 80-90 percent of the unwanted chubs, the lake could be restocked with fish-eating rainbow trout that could keep the chub population low. While the different netting techniques used by Schoans� crew caught chubs each of the past three days, the nets seemed to catch only the older and larger chubs over 2 inches long. That leaves the smaller chubs, all 22 million of them, unfazed by netting � as well as the estimated 4.6 billion chub eggs now in the lake. "As it stands right now, we�re not going to kick the chubs down enough to recover the ecosystem," says Steve Denney, the ODFW�s Umpqua watershed manager. "I�d say the netting�s not going to do it." This grim realization is the latest step in the long journey toward reclaiming Diamond Lake�s title as Oregon�s most popular trout-fishing lake, a title stolen by the invading chubs. The chubs, a native of the Klamath basin, were likely introduced illegally as bait by an unknown fisherman in the late 1980s. By the early �90s, the population exploded to where the chubs out-compete trout for food and space. The chubs have chased away anglers who once logged 100,000 fishing days and spent $2 million a year on fishing this High Cascades lake in eastern Douglas County. ODFW officials want to draw the lake down and treat the water with the chemical rotenone, which will kill off all the fish but leave the insects alone. The agency would then start over from scratch by restocking the lake with the desired rainbow trout. The U.S. Fish and Wildlife Service is currently conducting a full study of the different options as well as their anticipated effects to the environment. Schoans� crew on Monday and Tuesday used a large beach seine to catch chubs from the shallow near-shore waters, then began experimenting Wednesday with a large purse-seine used to corral and capture the chubs in the lake�s deep, open waters. But the fish seemed to be scattered in small schools that were easily spooked. While the nets caught fish, they never hit the Mother Lode as Schoans expected. "We�re catching 5 percent of what I thought we�d catch," Schoans says. "Rotenone is definitely the answer." Though disappointing, the experiment is far from a failure, says biologist Dave Loomis, the ODFW�s point-man on the chub saga. One concern about using rotenone is that it leaves a large mass of dead and decaying fish in its wake. So much so, in fact, that it could overload the lake with nutrients that could flow down into the North Umpqua River system and harm the river�s water quality and wild fish. The experiment shows that nets can remove the larger, heavier fish well enough, perhaps, to cut in half the lake�s estimated 100,000 pounds of chubs, Loomis says. That could ease the nutrient fallout from chemical treatment, he says. "But as far as effectively removing a large number of chubs, we�re never going to get anywhere near total removal," Loomis says. "But this is money well-spent," he adds, "to help determine how we�re going to manage Diamond Lake in the future." Staff writer Mark Freeman covers the outdoors for the Mail Tribune. 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