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sources (Yampa and Little Snake rivers) were reported not to have changed <br />significantly in sediment discharge. <br />Grams and Schmidt (1997) reported continued channel narrowing in <br />meandering reaches (unconfined reaches) downstream from Lodore Canyon on <br />the middle Green River. This process occurs in mid-channel, bar-depositional <br />facies and involves progressive filling of side channels and eventual attachment <br />of islands to an adjacent bank. <br />Recruitment failure related to poor reproductive conditions <br />Because sand deposition has been noted over the main spawning site on <br />the middle Green River (Tyus and Karp, 1990), concern was raised by fish <br />biologists regarding possible effects of sedimentation on spawning success. <br />This concern prompted initiation of this study of the primary spawning site to <br />determine the dynamics of sediment movement. The majority of observations <br />of spawning have been associated with gravel and cobble substrates, and <br />razorback appear to work spawning substrates to clean them of sediments based <br />on observations of worn caudal and anal fins during the spawning period. <br />Sedimentation of primary spawning bar sites may be a key factor contributing <br />to recruitment failure during some years. <br />Successful recruitment of razorback sucker through their first year of <br />life has two major steps. <br />1. successful spawning, egg deposition, and hatch of larvae from <br />primary spawning sites <br />2. larvae must have access to suitable nursery sites with adequate food <br />connectivity duration for growth and cover to avoid predators <br />Obviously, good production of larvae from spawning sites is an <br />important first step to recruitment success. It is important to match good <br />nursery habitat conditions in terms of timing and duration with flow years in <br />which spawning and hatching of larvae are successful. This successful match <br />27 <br />l_