Habitat measurement and modeling in the Green and Yampa Rivers: Project Report to Natural Resource Preservation Program December 2001

Populations of the endangered razorback sucker (Xyrauchen texanus) in the middle Green River have declined since closer of Flaming Gorge Dam in 1962. The apparent cause for the decline is a lack of successful recruitment. Recruitment failure has been attributed to habitat alteration and competition and predation by exotic fishes on early life stages of razorback sucker. This study was conducted to evaluate two of the potential reproductive bottlenecks that might limit recruitment of razorback sucker in the Green River Drainage; (1) reduced larvae production due to sediment deposition on spawning areas, and (2) reduced survival of larvae or juveniles due to lack of timely access to rood-rich backwater and floodplain habitats.