Three bald eagles plucking 6-inch tui chubs off the surface of Fish Lake, to the amazement of summer campers there, illustrated the best and the worst the High Cascades lake has to offer.
The eagles are a fixture at this lake 30 miles east of Medford, where nature is never far away.
"These eagles were really putting on quite a show," says Fish Lake Resort owner Jim Blodgett. "But it was going on because of a problem."
The problem is that even after the use of trap nets, commercial fishing nets and four rounds of poisonings, illegally introduced tui chub still dominate the lake's ecosystem — to the point that the lake's famed trout fishing has tapered off and potentially toxic algae blooms mar the water each summer.
State fish biologists even released spring chinook salmon into the lake, hoping they would eat enough chub to make a difference and create a unique fishery at the same time.
The next weapon to be unleashed in Fish Lake's chub war will be tiger trout — a sterile cross between brook trout and brown trout.
The predators will be released this fall and could be large enough by next summer to start taking chunks out of the lake's estimated population of one million chub.
"This is a unique situation and we're going to respond in a unique way," says Dan VanDyke, the Oregon Department of Fish and Wildlife's Rogue District fish biologist.
Plans are to release 4,000 of the 4-inch tiger trout this fall and at least 20,000 more over the next three or four years. Another 4,000 of the trout will be dumped this fall into Northeast Oregon's Phillips Reservoir, which faces a threat from illegally stocked yellow perch.
On Friday, the Oregon Fish and Wildlife Commission is set to adopt new rules to allow catch-and-release fishing for tiger trout beginning next year.
By next summer, some of the trout should have grown to about 15 inches long by feeding on chubs.
"Our primary objective is to add to the angling diversity in the area," VanDyke says. "Any biological control is just going to be a benefit."
Newspaper accounts show that tui chub, which are native to Klamath Lake, first showed up in Fish Lake in the mid-1940s, likely brought as minnows by some angler. They overran the lake in no time, much as they did at Diamond Lake the following decade.
Diamond Lake was poisoned in 1954 to kill off the chub, and that treatment lasted until they reappeared in the early 1990s. Diamond was poisoned again in 2006, then restocked in 2007. It is now the Northwest's best trout-fishing lake and remains chub-free.
At Fish Lake, however, the chub have been harder to eradicate.
"I consider it a mini Diamond Lake, with an unfortunate twist," VanDyke says.
The twist is that Fish Lake is loaded with springs, making it impervious to poisoning with rotenone. ODFW poisoned Fish Lake with rotenone in 1951, but enough chub survived in the springs to repopulate the lake.
Similar efforts in 1966, 1976 and 1985 failed, as well, so rotenone is off the table as a chub solution at Fish Lake.
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 more expensive rate.
In 2007, the Forest Service began an aggressive netting program that removed close to a million chub through last fall. That netting program will sunset after this year, but Blodgett says he will keep at it on his own.
In an effort to find a fish that can feed on the chub, ODFW stocked the lake with excess Rogue River spring chinook and changed the angling rules to treat them as trout beginning this year.
But the real test comes with the tiger trout.
Oregon received about 50,000 tiger trout eggs from Washington for free and began rearing them at Klamath Hatchery. But the tigers are tough to raise and only about 8,000 survived, says Bruce McIntosh, ODFW's assistant Fish Division administrator for Inland Fisheries.
Plans are to watch 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, McIntosh says.
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, McIntosh says. If the experiment fails, the tiger trout will die off and it's game over, he says.
"It's a reversible reality," he says.
But chances are good that some of the stocked tigers will eclipse 20 inches long and not only feast on chub but also provide some good entertainment for anglers.
"They can definitely do some chowing when they get that big," McIntosh says. "Hopefully, we can make some kind of dent in the chub (population)."
Reach reporter Mark Freeman at 541-776-4470, or email at firstname.lastname@example.org.