title: Influence of multiple dam passage on survival of juvenile Chinook salmon in the Columbia River estuary and coastal ocean.
abstract: Multiple dam passage during seaward migration is thought to reduce the subsequent survival of Snake River Chinook salmon. This hypothesis developed because juvenile Chinook salmon from the Snake River, the Columbia River's largest tributary, migrate >700 km through eight hydropower dams and have lower adult return rates than downstream populations that migrate through only 3 or 4 dams. Using a large-scale telemetry array, we tested whether survival of hatchery-reared juvenile Snake River spring Chinook salmon is reduced in the estuary and coastal ocean relative to a downstream, hatchery-reared population from the Yakima River. During the initial 750-km, 1-mo-long migration through the estuary and coastal ocean, we found no evidence of differential survival; therefore, poorer adult returns of Snake River Chinook may develop far from the Columbia River. Thus, hydrosystem mitigation efforts may be ineffective if differential mortality rates develop in the North Pacific Ocean for reasons unrelated to dam passage.
authors.affiliation: Kintama Research Services Ltd., Nanaimo, BC, Canada V9S 3B3. erin.rechisky@kintama.com
authors.forename: Erin L
authors.initials: EL
authors.lastname: Rechisky
authors.forename: David W
authors.initials: DW
authors.lastname: Welch
authors.forename: Aswea D
authors.initials: AD
authors.lastname: Porter
authors.forename: Melinda C
authors.initials: MC
authors.lastname: Jacobs-Scott
authors.forename: Paul M
authors.initials: PM
authors.lastname: Winchell
mesh_terms: D025041:Animal Migration; D000818:Animals; D005398:Fisheries / Q000379:methods / Q000706:statistics & numerical data*; D009922:Oregon; D010140:Pacific Ocean; D011157:Population Dynamics; D045483:Rivers; D012474:Salmon / Q000502:physiology*; D016019:Survival Analysis; D013686:Telemetry; D014861:Washington