Home  News and Press Releases Smolt by the numbers: Water traps help capture small fry as part of
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DRY CREEK -- Smolt traps look like "Star Trek"-esque spinning tops on their sides, ready to lift adjoining pontoons from creeks, yet their function is what's really futuristic. Smolt traps capture small fry and yearling smolts as part of a monitoring project to count fish production on the upper North Umpqua River and its tributaries. They give agencies information on where anadramous fish, which go upstream from salt water to fresh water to spawn, go and in what numbers since they are blocked by Soda Springs Dam, a manmade barrier that will have a fish ladder constructed around it in the future. "We need to know fish numbers, and it's a No. 1 technique to find fish populations," said Bob Kinyon, executive director of Partnership for Umpqua Rivers. Counting fish with smolt traps is part of PacifiCorp's 35-year relicensing settlement agreement with the U.S. Forest Service, the Oregon Department of Fish and Wildlife, and other state and federal agencies for its 185-megawatt North Umpqua Hydroelectric Project. A fish ladder at Soda Springs Dam will provide access for fish to at least six more miles of upstream spawning habitat. But before a ladder is built, smolt traps will provide years of fish monitoring in areas that fish biologists suspect may be partially abandoned by fish once they have access to higher spawning grounds.
The fish passage is one of three major elements in PacifiCorp's relicensing agreement that includes habitat improvement and flow improvement. Smolt trap monitoring will continue after the fish ladder is in place to conclude whether fish choose higher North Umpqua waters over lower tributaries and whether the fish ladder is a success. Sam Moyers, ODFW's assistant Roseburg district fish biologist, said many smolt traps exist in the Umpqua watershed for other agency studies, but the PacifiCorp agreement places three traps high on the North Umpqua. They are located in the North Umpqua, just beneath Soda Springs Dam, and in Calf Creek and Copeland Creek, close to where they empty into the North Umpqua. Trap monitoring began in late March and will continue either through October or the rest of the year. "It's a pretty effective fish-catching machine," Moyers said of the smolt traps. Since fish ladder construction is still years away, smolt traps in Copeland and Calf creeks will serve an experiment in fish habitat rehabilitation. Copeland Creek will receive log placement this summer, followed by boulder placement. The extra bulk is expected to slow downstream-moving debris such as pebbles and logs during high flows so they deposit in stream pools and create more spawning habitat.
The smolt traps in Copeland and Calf creeks are 5 feet in diameter, while the trap in the North Umpqua is 8 feet in diameter. They are rotating funnels of steel mesh with their openings facing upstream. A live well is placed at the end of the funnel for collecting trapped fish. The funnels turn clockwise by swift-moving water pushing paddles that screw down the inside of the funnels. Fry and smolt migrate downstream tail first, so essentially they float unaware into the traps and are whirled down the funnel and into the live well. "By the time a fish figures out it's in a trap, it's too late," Moyers said. The traps are checked every morning by a rotating crew of three workers who work in pairs and are employed by Partnership for Umpqua Rivers. They count fry and smolt collected in each trap and take measurements. So far, it's mostly coho salmon fry and fingerling steelhead smolt that the traps are collecting. Trap workers mark the tail ends of fry and smolt with a slight clipping for future accountability. They are then released upstream of traps so workers can count clipped fish and new fish caught each day. Clipped fish caught twice are re-released downstream so they don't figure back into the trap's creel count. By counting new fish caught each day, fish biologists can determine a percentage of clipped coho, chinook and steelhead fry and smolt in a creek's run and get that run's overall number. "If we catch 100 (clipped coho), and that's only 10 percent of what's through, the run is about 1,000," said trap worker Alex Farrand. You can reach reporter Adam Pearson at 957-4213 or by e-mail at This e-mail address is being protected from spambots. You need JavaScript enabled to view it . |
Adam Pearson
PacifiCorp spokesman Dave Kvamme said by 2010 a fish ladder is expected to be built at Soda Springs Dam, which is located about 60 miles east of Roseburg. By 2012, a screen will be placed in front of the generator to block downstream migrating fish from getting sucked into its turbines.
Calf Creek will serve as the control and won't receive any log or boulder placement. Biologists will later look at the two creeks' fish runs and determine the effectiveness of stream rehabilitation.