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difference (p< .01) in depths recorded between the Green River and the two tributaries, but the depths recorded between-the White and Yampa were not significantly different. These results are supported by the analyses of data collected with conventional gear, i.e.: Seines, nets, electrofishing (Fig. 14). Similarly, ANOVA produced no significant difference (p V 01) between water velocity readings taken from Colorado squawfish locations in the Green River in 1980 and 1981, but there were significant differences (p x.01) between water velocities recorded for each river system. It is not known whether Colorado squawfish selected different conditions between river systems or were able to tolerate the wide range of conditions present between mainstem and tributary rivers. Habitat preference curves for adult Colorado squawfish were not generated for this report. We decided that such curves would be pre- liminary and prefer to await the conclusion of current radiotelemetry studies (Miller et al. 1983a,b). In view of the increasing amount of radiotelemetry data, we suggest the use of earlier habitat preference data from collections of Colorado squawfish with nets and electrofishing be deferred in favor of the more representative radiotelemetry data when it is finalized. At that time, further comparison of habitat use by river system and time of year can also be made, with the objective of preparing Colorado squawfish habitat preference curves for each river. Spawning Spawning habitat of Colorado squawfish was located in 1981 (Tyus et al. 1982) when eight Colorado squawfish were radiotracked from the upper Yampa and Green rivers to spawning grounds in the lower 32 km of the Yampa River. Seven Colorado squawfish migrated from 205 km to 160 km downstream in the Yampa River and one migrated 154 km upstream from the Green River to enter the spawning grounds. Radiotagged fish remained in the lower Yampa Canyon from June 26 to July 10. On July 1, 1981 a radiotagged Colorado squawfish was followed to a potential spawning area at RK 29.6 on the Yampa River. Collections in this area produced two ripe male Colorado squawfish. Efforts to locate spawning fish were increased and on July 5, 1981 three radiotagged Colorado squawfish were located at RK 26.4 in the same general area of the Yampa River. These fish were moving between a deep pool and a shallow cobble-rubble bar (Fig. 15). This behavior appeared to be associated with spawning, and was similar to that reported by Beamesderfer and Congleton (1981) for spawning northern squawfish (P. oregonensis). A floating trammel net was fished over the bar and associated pool hab- itats; 13 ripe Colorado squawfish were captured in one net, and 2 were collected in the second. All of these Colorado squawfish appeared to be ripe males except one, a large (779 mm) fish which appeared to be a spent female. All fish were heavily tuberculated and milt was flowing from some of the suspected males. 27