Adult steelhead Oncorhynchus mykiss tagged with archival transmitters primarily migrated through a large river corridor at depths >2 m interspersed with frequent but short ( Oncorhynchus tshawytscha study, except O. mykiss experienced greater seasonal variability and were more likely to have depth uncompensated supersaturation exposure in some dam tailraces, perhaps explaining the higher incidence of GBD in this species.

Two non‐direct homing behaviours, overshoot of natal tributaries and temporary non‐natal tributary use, were evaluated for 5150 radio‐tagged spring–summer Chinook salmon Oncorhynchus tshawytscha from 40 populations in the large Columbia River system. Over 7 years, 2–44% (mean = 15%) of individuals within each group temporarily entered presumed non‐natal tributaries. In addition, many Chinook salmon from lower river tributaries...

Unusually long downstream movements totalling several hundred kilometres to >1100 km were observed during upstream homing migrations of radio‐tagged spring chinook salmon Oncorhynchus tshawytscha in the Columbia and Snake Rivers, U.S.A. Downstream migrants, identified by their repeated ascension and fallback over a series of large hydroelectric dams within the migration corridor, were primarily hatchery‐origin males.

Upstream migration rates were assessed for 1801 radio‐tagged adult spring–summer Chinook salmon Oncorhynchus tshawytscha through 12 unimpounded river reaches in the Columbia River basin from 1997 to 2002. Reaches were 36 to 241 km long (mean = 130 km) and included sections of the large Columbia and Snake Rivers and smaller free‐flowing tributaries. Median Chinook salmon migration rates ranged from −1 in the Deschutes and Clear...