No Bull: Researchers Find these "Trout"
by Allen Thomas, Columbian staff writer
Steve Gray has a slide that's a collage of an alien, a sasquatch and a bull trout in his PowerPoint presentation.
The text with the slide asks: "Have You Seen Us?"
He's not kidding.
It's part of the peril of being a bull trout researcher in the Columbia River's Bonneville pool and tributary streams.
Gray's task is to learn where the bull trout live, their movement patterns and estimated population size.
What makes this such a challenge is bull trout are extremely hard to locate and capture, so they can be fitted with radio transmitters and other tags.
Bull trout are listed as threatened under the federal Endangered Species Act. The U.S. Fish and Wildlife Service directed in 2000 that a study of the bull trout in the lower Columbia River reservoirs would be conducted.
Bonneville Power Administration is paying for the study to the tune of $305,000 annually, each year contingent upon the results.
Which brings us back to Gray.
He's trying to learn more about the bull trout that use the Columbia River between Bonneville and The Dalles dams, including the major tributaries. Those streams include the Wind, Little White Salmon, White Salmon and Klickitat rivers in Washington.
Here's what's known:
The highlight of their work this year came April 14, when an electroshocking crew from the Oregon Department of Fish and Wildlife's pikeminnow research effort captured an 18-inch bull trout in the Columbia River about a quarter-mile east of the bridge across the mouth of the Little White Salmon River.
The Oregon crew placed the bull trout in a live tube with a rope and buoy, returned it to the river, and called Gray.
By 1:30 a.m., Gray and Pyzik were on the Columbia and had the bull trout. The fish received a visual tag, a radio tag, and a had a radio transmitter surgically insert in the belly. Six days later, it was released back at the Columbia at its point of capture.
Gray's crew named the fish "Sale 182" (Sale is short for salvelinus, the genus for bull trout, and 182 refers to the transmitter code).
Sale 182's radio signal showed up near the mouth of the Wind River on June 9. She appeared to be moving. After June 20, the transmitter seemed stationary about 200 yards west of the point at the mouth of the Wind.
In mid-October, Gray recovered the tag about 200 yards west of the point at the mouth of the Wind River along the shoreline in about three feet of water.
Did Sale 182 die or somehow shed her transmitter?
Gray said, based on discussions with other bull trout biologists, he believes she shed her transmitter. "It has been found absorbable sutures do not disintegrate at water temperatures within the streams and reservoirs that these fish inhabit," he said. "The sutures eventually cut their way through the skin and the tag then falls out as the fish swims along."
Sale 182 also has a "passive integrated transponder," which sends out a signal. It is hoped her signal will be read at a monitoring station.
But the capture of Sale 182 near Drano Lake, along with other anecdotal information, identifies the backwater as a good location to sample for bull trout, known for their diet of other fish. Little White Salmon National Fish Hatchery, just up the river from Drano Lake, releases millions of young salmon a year.
"What we theorize is that the bull trout caught in Drano come here based on prey availability," Gray said. "The timing is such that fall chinook are being released, and all the coho have been released. There's a gluttony of fish out there. I think they've been conditioned due to the concentration of fall chinook in and around Drano Lake, that they will migrate to this prey availability source."
Based on that theory, Gray sampled the lake intensively in April through July. He tried beach seines, trap nets, small-mesh tangle nets and a mid-water minnow net.
Twenty-two nights on Drano, with 161 net sets, came up with lots of other fish. But no bull trout.
Another major part of the Bonneville bull trout research is monitoring fish passage at Lyle Falls on the lower Klickitat.
Modifications of the trap at the fall's fish ladder allows state and tribal biologists to monitor and record passage. A wealth of new information about spring and fall chinook, coho, and winter and summer steelhead is being learned.
But so far, no bull trout. There is a list of documented and anecdotal encounters with bull trout in the Klickitat.
For example, state workers handnetted a pair of bull trout hanging out for several days just downstream of Klickitat Salmon Hatchery.
Like netting at Drano Lake, the Lyle Falls trap appears a decent bet for intercepting bull trout, which then will get radio transmitters inserted.
Bull trout are not quite as elusive as Bigfoot, but almost.
Gray said, "There's kind of a joke amongst the bull trout society: What's the probability of finding zero and how can you, with a degree of confidence, sample and say nothing is there."
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