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The differences in abundances of carp and suckers between the braided channel area and canyon area, were a reflection of the obvious difference in habitat variability/availability between the two areas of the river. The braided channel area contained variable substrates (cobble, gravel, sand, boulder, and bedrock) and in varying propor- tions depending on location and discharge. Some in-stream structure in the form of snags was observed in the braided channel area. A wide variety of depths and velocities were present in the braided channel area. Deep, fast runs were present along shorelines, and occasionally eddies and backwaters were encountered. Few backwaters were observed until low flow conditions occurred in late summer and f all. At the upstream and downstream ends of the numerous islands, riffles were usually present. The habitat diversity in the canyon area appeared much less. The river is confined to a single channel which appeared to have relatively fast, uniform velocities across the channel; substrates of mainly sand or boulder/bedrock (although our observa- tions of substrates in the canyon were limited by velocities and depths which prevented us from doing as much wading as in the upper area). Few backwaters and a limited number of noticeable riffle - pool sequences were found in the canyon area. Large, deep eddies, such as those found in Westwater Canyon of the Colorado River and in Desolation Canyon of the Green River, were not noted in the canyons of the San Juan River. Discussion of the occurrence and suitability of habitat in the San Juan River, Utah for Colorado squawfish focuses on three life history stages: spawning; YOY and juvenile, and adult. The Colorado squawfish spawning area identified in the Yampa River provides clean cobble in deep water (3-7 ft) with velocities of 0-2.8 ft/sec (Miller et al. 1982). There does appear to be potential for Colorado squaw- fish spawning habitat to exist in the San Juan River, Utah. The grad- ient of the river is relatively high and our observations indicated cobble substrate to be common in the braided channel area of the river. The high flows of 1987 also appeared to provide suitable depths. Sedimentation and smothering of embryos may, however, be a limiting factor. Holden et al. (1980) found the proportion of sand substrate in the San Juan River increased downstream, especially below the Animas River confluence. Further investigation is required to identify spawning areas and gain a better estimate of the amount of squawfish reproduction occurring in the San Juan River, Utah. Assess- ment of the suitability of spawning habitat (including thermal as well as physical characteristics) in the San Juan River needs further in- vestigation. Identification of squawfish spawning areas in the Upper Colorado River Basin have been made through biotelemetry monitoring of mature, wild adults. At this time it appears that this technique may be of limited value in the San Juan River because of the apparent low density of adult fish; it may be difficult to capture wild adults for radio tag implantation. The collection of YOY Colorado squawfish did occur, but apparently to a limited degree. of backwater formation, basically controlled - 40 - proves that reproduction The seasonal dynamics by discharge, may cause r .-~ ~.