DIURNAL SHIFTS IN USE OF SUMMER HABITAT BY AGE-0 BROWN TROUT IN A REGULATED MOUNTAIN STREAM

Diurnal shifts in habitat use by age-0 (< 50 mm total length) brown tr out (Salmo trutta) were observed from June to July 1989 and 1990 in lo w-gradient (< 1% channel slope) reaches of Douglas Creek, Medicine Bow National Forest, Wyoming. Fish were visually located during day and n ight, and water depth, water velocity, distance from the stream edge, substrate, habitat type, and cover were determined at each location. T he fish were found predominantly in locations with slow water velociti es in stream-margin and backwater-pool habitats. They were observed in slower water, closer to the stream edge at night than during the day.