HORIZONTAL AND VERTICAL MOVEMENTS OF ADULT STEELHEAD TROUT, ONCORHYNCHUS-MYKISS, IN THE DEAN AND FISHER CHANNELS, BRITISH-COLUMBIA

Steelhead averaged 17.2 ± 2.2 (SE) km/d to travel 96.4 km from the capture/release site to the Dean River mouth. Gross and net travel rates averaged 2.0 and 0.8 km/h, respectively, indicating considerable milling by the fish. Gross movement during daylight (mean 2.2 km/h) was twice that during the night (1.1 km/h); most movement at night was attributed to tidal currents. The steelhead swam primarily on the surface throughout the fjord, regardless of salinity and temperature stratification. Geometric mean depth was 1.6 m and the fish spent, on average, 72% of the time in the top 1 m (the warmest and least saline water available). Median time between dives to 5 m (near the halocline) was 9 min, although 14% of the surface intervals exceeded 1 h. -from Authors