Laserfiche WebLink
Abstract.-Age-O Colorado squawfish Ptychocheilus Lucius (N = 11,379) \ <br />were captured in drift nets and seines in the Green and Yampa rivers 1979- <br />1988. Larvae were captured in stream drift (N = 601) in June and July, and <br />small postlarvae were captured in shoreline habitats (N = 3,079) in July <br />and August. The young fish appeared in drift nets about 47 d after the <br />peak spring discharge, and thereafter for about 2-6 weeks. Larval <br />Colorado squawfish moved downstream soon after hatching. By autumn, <br />postlarvae were most abundant (N = 6,459) in lower gradient reaches of the <br />Green River, about 150 km below the Yampa River spawning area (River km <br />(RK) 335-450); and about 130 km below the Green River spawning area (RK 50 <br />-160). Postlarvae were most abundant in shoreline embayments (backwaters) <br />and they occurred most frequently (80%, N = 5,043) in backwaters that were <br />relatively warm (z = 15.OoC upper; x = 19.0°C lower Green River), deep (x <br />= 42 cm lower; z = 34 cm upper), large (x 1,158 m2 upper; x = 494 m2, <br />lower) and turbid. Abundance and size of young Colorado squawfish in the <br />Green River were inversely correlated with high releases from Flaming <br />Gorge Dam, which inundated backwater habitats. We were unable to detect <br />overwintering mortality by comparing seine catches of the fish in autumn <br />and the following spring. <br />2 <br />