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areas in the middle and lower Green River, downstream from Jensen, Utah; <br />and (3) squawfish that establish residency in the Yampa River tend to <br />remain within their home range throughout the year except to spawn. <br />Twelve larvae were captured below river km 18, indicating successful <br />Colorado squawfish reproduction in the Lower Yampa River. Our collections <br />and those of others suggest that larvae tend to drift or move down the <br />Yampa River and into and down the Green River. <br />Habitat use varied seasonally based on flow and habitat availability. <br />During high flows, squawfish tend to move out of the main river into <br />low-velocity eddies and backwaters. At low flow they tend to move back <br />into the main river, using pools and runs. Flooded backwater habitats <br />used by Colorado squawfish during runoff may play an important role in <br />preconditioning fish for spawning by providing warmer water and feeding <br />or resting areas. <br />Water temperature is a primary factor influencing spawning time. <br />Migration occurred as fish temperatures approached 16°C. Fish were in <br />the spawning area as temperatures approached 19°C and spawning behavior <br />was observed after fish temperatures exceeded 19°C. Alterations of <br />Yampa River flow and temperature regimes could affect the reproductive <br />success of Colorado squawfish spawning within the boundaries of Dinosaur <br />National Monument. <br />vi