John Day Origin PIT Tagged Steelhead, Where Are They Going

John Day River Steelhead: In Through the Out Door

Tim Unterwegner and Jim Ruzycki - Oregon Department of Fish and Wildlife, John Day, OR

The John Day River is one of the longest free flowing rivers in the lower 48 states and is managed exclusively for wild anadromous fish production. Although no releases of hatchery fish occur in the basin, recent evidence suggests a relatively high percentage of returning adult steelhead are of hatchery origin. Detections in the migration corridor also suggest that John Day fish stray afrom their natal watershed. We began tagging wild juvenile steelhead in 2001 with Passive Integrated Transponder (PIT) tags in an effort to determine smolt to adult survival (SAR) and track movement of juveniles and adults. Tracking was accomplished using the Columbia River PIT tag information system (PTAGIS). This system allows us to track the movement of tagged fish as they are detected at antennas throughout the Columbia River basin. To date, 13,910 wild juvenile steelhead have been tagged in the John Day River and 307 returning adults detected at Bonneville Dam, the lowermost dam on the Columbia River. In September 2007, a prototype antenna array was installed by Biomark Inc. on the John Day River, with the primary purpose of determining the incidence and origin of stray steelhead. SAR of John Day River steelhead to Bonneville Dam has varied from 1.4% to 2.9%. Observations from recent surveys in the basin indicate that 29– 41% of adults throughout the basin are of hatchery origin. Greater than 50% of returning John Day origin steelhead pass over McNary Dam which is 74 miles upstream of the mouth of the John Day River. Hatchery steelhead straying into the John Day primarily originate from Snake River releases and so far, these stray fish were primarily transported as smolts in barges down the Snake and Columbia River corridors. Our evidence indicates clear exchange of steelhead among populations of the Columbia River basin.

2008 Pacific Coast Steelhead Meeting Boise, ID March 4-6, 2008