This pilot study was initiated to investigate movement patterns, habitat utilization, and velocity preferences for young of the year coho salmon (Oncorhynchus kisutch) during the spring in Western Washington and to examine potential factors controlling redistribution timing in the fall.
Water velocity appeared to be an important factor in predicting juvenile coho (<55 mm) distribution. Mark-recapture studies indicated that upstream movement by juvenile coho through culverts is low. Timing for fall redistribution of juvenile coho from main channels into off-channel habitat was investigated in relation to water temperature, stream flow, date, and moon phase. The majority of movement by juvenile coho in the Skagit, Suiattle, and Stillaguamish River basins occurred during new and half moon phases. Movement into off-channel habitat by juvenile coho in the Hoh River basin corresponded with floods where flow increased by 2000 cubic feet per second and coincided with a new moon. Studies at Remote Site Incubators indicate that recently emerged coho fry move upstream and downstream. Upstream movement ranged between 100 and 200 meters from April through June. After June, coho fry were found over 500 meters upstream.