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I I I I I I I I I I I I I I I I I I I MOVEMENT BY ADULT COLORADO SQUAWFISH AND RAZORBACK SUCKERS UNDER FLUCTUATING FLOWS IS FURTHER AGGRAVATED BY SHIFTING AND FLOATING ICE MASSES DURING PERIODIC BREAKUPS. River ice buildup in January and Febmary can frequently become broken and transponed downstream. The buildup of ice can occur overnight during low flows and cold air temperatures. A subsequent increase in flow can dislodge and transport the ice downstream causing fish to move to dodge the ice masses. Thus, maximum flow fluctuations can cause ice buildup and transpon in January and February and cause additional movement by fish. ADULT COLORADO SQUAWFISH AND RAZORBACK SUCKERS UPSTREAM OF THE BONANZA BRIDGE ARE SUBJECTED TO FREQUENT FLOW FLUCTUATIONS AND UNKNOWN ADDITIONAL ENERGY EXPENDITURES Flow fluctuations of sufficient magnitude to cause fish to move extend as far downstream as Bonanza Bridge, about 120 miles downstream of Flaming Gorge Dam. We conclude that fish in the upper 55 miles of their distribution in the Green River can be expected to have to move more frequently than fish funher downstream in order to remain in suitable microhabitat. The effect of this energy expenditure on survival, growth, and reproductive potential is unknown. FLOW RElEASE SCENARIOS FROM FLAMING GORGE DAM THAT CREATE STAGE CHANGE RATES OF 5 CM/H OR MORE CAUSE MOVEMENT BY OVERWINTERING ADULT COLORADO SQUAWFISH AND RAZORBACK SUCKERS. Flow releases of 800 cfs followed by a maximum rate release of 4,200 cfs for 8 hours can result in a stage change sufficient to cause fish movement as far downstream as the Bonanza Bridge, 120 miles from Flaming Gorge Dam. A flow release of 800 cfs followed by 4,200 cfs for 4 hours results in a stage change of 5 cm/h or greater as far downstream as Jensen. Flow releases 01 800 to 4,200 cfs for 2 hours do not produce a stage change greater than 5 cm/h within the current known distribution of adult Colorado squawfish and razorback suckers. vii