Conservationists are looking for clues into the disappearance of the “B-run” steelhead trout headed back to Idaho waters for spawning. Idaho Fish and Game biologists reply the late run is not over yet.
Despite an early prediction of a strong return, the hefty fish that are the backbone of the Clearwater River steelhead production have yet to arrive.
Out of a total of 73,000 which passed Lower Granite Dam near Lewiston by Nov. 2, only 6,900 or 9.5 percent were B-run, Idaho Rivers United said. Most of the returning B-runs are hatchery-reared. The wild B-run return is even more disappointing at 1.3 percent of the total, or less than 1,000 fish.
“The Clearwater River is famous for its big B-run steelhead,” said Charles Ray of Idaho Rivers United. “But the fish aren’t showing up this year.”
Sharon Kiefer, anadromous coordinator for Idaho Fish and Game, updated the B-run over Lower Granite to about 8,000 fish, although the wild numbers are accurate.
Barging juvenile fish around the dams and warm temperatures in the reservoirs are the most likely causes for the problem, Ray said.
The Oregon Department of Fish and Wildlife noted in an Oct. 21 letter to the National Marine Fisheries Service that Oregon’s Deschutes River is overrun by steelhead which “stray” during their upstream migration.
Many of those fish are collected as juveniles at state and federal dams on the Columbia and Snake River dams, and barged downstream around the reservoirs.
Fish and Wildlife attributes the straying to the loss of the steelhead’s homing instinct, caused by being captured and barged.
In recent years, up to 75 percent of Idaho’s juvenile steelhead have been barged, rather than kept in the river.
“It’s no wonder the barged steelhead can’t find their way home,” Ray said. “They’ve imprinted on a barge instead of on the river.”
High water temperatures in the reservoirs compound the problem, he said. The reservoirs slow the water and allow it to warm up to temperatures which are harmful to cold-water fish.
The steelhead seek relief from the warm water and mistakenly flock up colder tributaries like the Deschutes. Some may eventually backtrack up to Idaho, but others do not make it. Ray said the reservoir temperatures this summer violated federal guidelines for anadromous species.
Kiefer said 100 to 300 fish are still passing the dam each day, so the late run is not over yet.
xxxx THE B-RUN B-run steelhead usually spend two years in the ocean before entering the river system in August. They are larger than A-run fish and spawn in the Clearwater. A-run fish spend one year in the ocean before returning to the Columbia in June, July and August.