January 15, 2016
ROSEBURG, Ore – The Oregon Department of Fish and Wildlife plans to add tiger trout to its standard Diamond Lake rainbow trout stocking this June. These brook and brown trout hybrids are reproductively sterile and known to prey on smaller fish – biologists are banking on them to help keep tui chub in check.
A single tui chub was found in a trap net this past fall, and biologists know all too well their life history of explosive population growth in Diamond Lake.
“We know what chub are capable of in Diamond Lake, and we are working with our partners to get ahead of the curve. We looked at many options, and tiger trout came out on top,” says Greg Huchko, Umpqua District Fish Biologist. “We wanted to stock a mix of brown and tiger trout, but only tigers are available this year. We will be looking into sterile brown trout for next year in addition to tiger trout.”
Huchko said he’s been meeting with the Umpqua National Forest, Douglas County, and the U.S. Fish and Wildlife Service to discuss stocking, and biologists agreed that stocking sterile tiger and/or brown trout was the best choice. Both species are known to prey on smaller fish.
“Many strains of rainbow trout have been stocked in the past, but unfortunately, our creel surveys showed that even those we thought would prey on tui chub were feeding primarily on insects,” Huchko said. “In the early 2000s, we also experimented with a stocking of North Umpqua strain spring chinook with the hope they would eat tui chub, but most of them migrated out of the lake.”
Fisheries biologists will monitor tiger trout abundance in Diamond Lake although they expect minimal numbers of these trout to migrate into Lake Creek.
“Our goal is to design and implement a stocking strategy that controls tui chub to maintain water quality and angling opportunities. 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,” said Jason Wilcox, Umpqua National Forest fisheries biologist.
Pending funding, ODFW plans to purchase up to 20,000 three-inch and 5,000 eight-inch tiger trout from Cold Springs Trout Farm, a private hatchery in Utah. The tiger trout would be in addition to ODFW’s regular stocking of 300,000 rainbow trout fingerlings and will likely be catch-and-release only to protect these fish and maintain their numbers.
ODFW and partners also outlined a stepped-up monitoring plan for Diamond Lake, including hiring two seasonal technicians to conduct additional removal of tui chub and golden shiners via beach seines, fyke nets, electro-fishing, and trap nets. Also, ODFW plans to monitor the tiger trout population by continuing creel surveys and operating a smolt trap near the lake’s outlet.
ODFW applied for grants to fund monitoring and fish stocking. The Umpqua Fisheries Enhancement Derby is also helping raise money by holding a “fish frenzy” at its annual derby banquet and auction Friday, January 29.
For every dollar donated, funds will be split to purchase both fish and capture nets for monitoring. A nights lodging in a cabin at Diamond Lake Resort and use of two large, two-person snowmobiles for the day comes with each $1,000 donation while a $500 donation receives a night’s lodging and use of two single-person snowmobiles.
In September 2006, ODFW successfully treated Diamond Lake with rotenone to eliminate an estimated 90 million tui chub at a cost of nearly $6 million, restoring water quality and the recreational rainbow trout fishery.