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<br />much of the substrate during low flow. Investigation and <br />refinement of suitable spawning locations in the target <br />reaches will continue annually up to release of the chemical <br />attractants for the experimental fish if necessary. <br /> <br />Task 2: Biological assessment in the unoccupied river reach <br />for non-native impacts, genetic stock management alternatives <br />and risks. <br /> <br />Sampling in the study reach would include characterization of <br />the existing fish community in the reach with emphasis on the <br />relative abundance of native and non-native species, the use <br />of spring and summer backwaters by potential predator or <br />competitor species, and the availability of suitable fish prey <br />for juvenile and adult Colorado' squawfish. Impacts to <br />Colorado Squawfish and razorback sucker from non-native fishes <br />would be analyzed through comparisons of length frequency <br />distributions, body and gape measurements, and d.iet assessment <br />for fish prey ingestion. <br />Concurrent to onsite collection of physical habitat data <br />by boat, the number of fish species, their relative abundance, <br />size structure, and piscivorous diet would be measured at each <br />habitat type as it is encountered in the target reach using <br />various sampling techniques in each habitat. Gape size on <br />potential predator species and body width-depth measurements <br />on potential prey species will be recorded. Ingested fish <br />prey will be characterized by species and size relative to <br />predator species and size, and compared to available fish prey <br />per habitat type. <br /> <br />Deliverables: No deliverables were planned for 1993. <br /> <br />VIII. Accomplishments and Shortcominqs: <br /> <br />Efforts were made in the summer and fall of 1993 to <br />characterize aquatic habitats, and the channel condition <br />between RM 240 and 196 (Rifle to Plateau Creek), All <br />backwaters observed (over 60 total) were enumerated and <br />measured during July and August. Also to assist in the <br />quantification of spring and summer backwaters a video flight <br />of the river reach was made on July 7, 1993. The flow of <br />8,014 cfs was recorded on this date for the gage near <br />Palisade, Prints from the video will be used to identify <br />bottomland and backwaters which appear suitable as nursery <br />habitat, or for nursery habitat (flooded-bottomland) <br />development. <br />Fall and winter pool/deep run habitats were quantified in <br />October and November as part of a general survey of four major <br />habitat types in this river section, Habitat units were <br />grouped into pools {backwater, eddy, trench, and lateral <br /> <br />4 <br />