Population-scale movement of coastal cutthroat trout in a naturally isolated stream network

To identify population‐scale patterns of movement, coastal cutthroat trout Oncorhynchus clarkii clarkii tagged and marked (35 radio‐tagged, 749 passive integrated transponder [PIT]‐tagged, and 3,025 fin‐clipped) were monitored from June 1999 to August 2000. The study watershed, located in western Oregon, was above a natural barrier to upstream movement. Emigration out of the watershed was estimated with a rotating fish trap. Approximately 70% of recaptured coastal cutthroat trout with PIT tags and 86% of those with radio tags moved predominantly at the channel‐unit scale (2–95 m); fewer tagged fish moved at the reach scale (66–734 m) and segment scale (229–3,479 m). In general, movement was greatest in April as spawning peaked and lowest in October, when discharge was at its lowest. Only 63 (