It almost seems like an unfair contest – an army of up to 25,000 tiger trout against a single minnow.
For Oregon Fish and Wildlife officials, however, the swift response reflects lessons learned – at a cost of $5.6 million, Mark Freeman reported for the Mail Tribune.
One tui chub minnow was found in the lake in October, but Oregon fish managers have battled the invasive species in Diamond Lake before. They hope to catch it early by employing maximum force against it.
Officials plan to release 20,000 smaller tiger trout and 5,000 larger trout into Diamond Lake in the spring, reported Robert Deen for the Anglers Club Magazine. The lake is already stocked with rainbow trout, but they eat insects and are not likely to help the tui chub problem.
“I’m hoping it was the only tui chub, but I’m operating on the assumption that it wasn’t,” Greg Huchko of the Oregon Fish and Wildlife Department told the Mail Tribune. “I’m hoping, in a year or two, this becomes a non-issue."
Some invasive species are targeted for extermination to save a weaker native species or out of a general desire to keep a habitat natural. The tai chub situation, however, is a different case.
Fishermen using a few tui chub as live bait accidentally introduced the species into Diamond Lake in the early 1990s, and the escaped minnows flourished into a thriving population of 90 million, the Mail Tribute reported. The tui chub overran the lake and out-competed the lake's trout, which hurt the area's fishing industry.
"It's not just a fishing issue," Huchko told the Mail Tribune. "It's a huge water-quality issue, as well."
The lake also developed a scummy bloom of neon green algae that was as toxic as it was ugly, and swimmers were barred for certain seasons for their own safety. After numerous efforts to contain the invasive minnow, the chemical rotenone was employed in 2006 to kill everything in the lake.
The solution was extreme, but it seemed to work, until a 4-year-old tui chub was discovered in October. Wildlife officials hope they have caught the problem early enough to thwart disaster, but they plan to take no chances. In addition to a veritable navy of tiger trout, Huchko plans to employ two fishermen who can operate a trap at the outlet for Diamond Lake, as well as net and electroshock by night, all at a cost of $35,000.
“The playing field's a little different now because we were able to catch it early,” Huchko told the Mail Tribune. “This isn't ideal, but we want to be as proactive as we can.”
The tiger trout – a hybrid of the brook and brown trout known for aggressive fish-eating – will likely come from a private fishery in Utah and cost about $1 per fish, Huchko told the Mail Tribune.
“Any tiger trout that may leave or be removed from Diamond Lake are sterile so there is not the risk of these fish species reproducing in the North Umpqua watershed or elsewhere,” Jason Wilcox, Umpqua National Forest fisheries biologist, told Anglers Club Magazine.
The Umpqua Fisheries Enhancement Derby will fundraise for the lake-saving effort with a "fishing frenzy" auction on Jan. 29.