In a challenging year for salmon and steelhead returns, Idaho’s most endangered salmon fared a little better than expected with 157 of them trapped in the Sawtooth Basin this summer.
“We are very pleased with this return given the estimate of only about 400 Idaho sockeye made it to Bonneville Dam this summer based on PIT tag estimates,” said Eric Johnson research fisheries biologist for Idaho Fish and Game.
Biologists were concerned about so few fish crossing Bonneville in early summer, which is the first dam in the Columbia River, and whether they would complete the 900-mile migration from the Pacific that includes crossing through eight dams and climbing 6,500-feet elevation to the Sawtooth Basin.
But Johnson said migration conditions were good for Idaho sockeye because rivers did not warm until most of the sockeye had already reached the Salmon River. Cool water from a higher-than-average snow pack helped their final leg from Lower Granite Dam about 30 miles downstream of Lewiston to the Sawtooth Basin.
“This year, we observed higher-than-average conversion rates between Lower Granite Dam and the Sawtooth Basin,” Johnson said.
The run is well-below last year’s return of 595 fish, and the second-lowest in a decade. The 10-year average is 690 sockeye trapped annually in the Sawtooth Basin, which ranged from a high of 1,579 to a low of 91.
While recent sockeye runs are tiny compared with other salmon runs, they’re a vast improvement over the 1990s. When Idaho sockeye were listed in 1991 under the federal Endangered Species Act, only four adults returned to the Sawtooth Basin. The combined annual returns from 1991-99 was 23 fish, which included two years when no Idaho sockeye returned.
Idaho has a three-prong strategy to recover sockeye. Adults returning from the ocean are collected annually in the Sawtooth Basin at Redfish Lake Creek and the nearby Sawtooth Fish Hatchery.
Some of those returning adults are spawned in the hatchery, and others released to spawn naturally in Redfish Lake. Fish and Game also raises in captivity a small population of adult sockeye that are spawned to augment those returning from ocean.
Those three sources provided about 740,000 young sockeye that were released, or naturally migrated from Redfish Lake, during spring.
Johnson said it’s still possible, but unlikely, more fish will return this fall.
“We will operate the trap until around the first of October in hopes of getting another fish or two, but I would not be surprised if this is our final count for the year,” he said.