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Daily movement budgets were also calculated for five fish over four separate days each (one day <br />for each of the summer months). These data suggest that northern pike spent approximately <br />52 % of their time in the main river channel in relatively deep water. Fish moved to the <br />upstream edges of sandbars at night and remained motionless. These areas had very low mean <br />velocities (0.01 m/s). Flow fields in these areas were typically composed of recirculating <br />currents with little or no net downstream movement. During the 24 observation days, 11 % of <br />the fish showed no movement during the day and 26% did not move during the night. The <br />maximum movement over a 1-h period was 225 m. On average, pike moved 43.7 m/h during <br />the day (56.6 S.D.) and 5.9 m/h at night (28.4 S.D.). <br />Temperatures were measured at least weekly throughout the year in habitats where pike were <br />observed. Mean daytime temperatures were 22.5, 18, 8 and 12 for the summer, fall, winter and <br />spring respectively. Mean, nighttime temperatures were 14.1, 12.2, 4.6 and 7.7 for the four <br />seasons. <br />Diet Composition <br />Twenty-six northern pike were captured and examined for stomach contents from the Ouray <br />subpopulation during spring, summer, and fall 1993, and spring 1994. Only one. of eight pike <br />captured in October (fall 1993) contained prey (common carp). Sixteen of the 18 pike sampled <br />in spring contained prey. Juvenile Colorado squawfish (total length = 45-54 mm) were only <br />found in stomachs of age-4 northern pike (500-600 mm fork length), and represented 13 % of <br />their diet by wet weight (Figure 1). -When averaged across ail ages of pike, the diet consisted <br />of 5 % j uvenile Colorado squawfish, 72 % other cyprinids (red shiners, redside shiners, common <br />carp, and unidentified cyprinids), 6% suckers (Catostomus spp.), 6% crayfish, and 11 % mice. <br />