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, ' .. June 1991 back chub (219 mm and 310 mm TL) collected on 8 June had breeding tubercles. The Colorado squawfish, one of the radiotagged fish (824 mm TL), was neither tuberculate nor ripe: it was collected from an eddy 1 m deep with sand sub- strate. Numerically dominant species collected were Colorado roundtail chub (53%), flannel- mouth sucker (Catostomus latiPinnis; 20%), com- mon carp (Cyprinus carpio; 11%), and channel catfish (Ictalurus punctatus; 9%). Species collected in small numbers ( < 3%) included bluehead suck- er (Catostomus discobolus), black bullhead (Icta- lurus melas), and white sucker (Catostomus com- mersoni). Fine-mesh seine (3 by 1 m, 1.5-mm mesh) and dipnet (1.5-mm mesh) collections were conducted on 28 June 1988 after radiotagged squawfish had left the Little Snake River. We collected 1,260 fishes ranging from 10 to 30 mm TL. Flannel- mouth sucker made up 82% of all young collected, and bluehead sucker made up 17%. Other species collected in small numbers included sand shiner (NotroPis stramineus), speckled dace (Rhinichthys osculus), and Colorado roundtail chub. The Little Snake River provided habitat for Colorado squawfish and humpback chub during the spring, when high discharge provided suitable habitat. Adult Colorado squawfish may move from the Yampa River to the Little Snake River to take advantage of warmer water temperatures and feeding opportunities. Juvenile Colorado roundtail chub and suckers observed in the Little Snake River may provide prey for adult Colorado squawfish. Warmer water temperatures and readily available feeding opportunities are con-' sidered important in conditioning fish for migra- tion and spawning (McKeown, 1984). Adult Col- orado squawfish also used backwaters and flooded mouths of smaller tributaries on the Yampa and Colorado rivers during spring runoff, and such use may be important in physiological prepara- tion for spawning. These habitats provide more abundant forage and warmer water temperatures than the main channel (Holden and Wick, 1982). Potential spawning habitat for Colorado squawfish near the location of radiotagged fish led us to suspect that spawning might be occur- ring in the canyon area of the Little Snake River. However, further investigations suggested that Colorado squawfish left the Little Snake River prior to spawning. Observations supporting this conclusion included lack of tuberculation or ex- pressible gametes from the one large adult Col- Notes 253 FIG. 2-Photo of 310 mrn total length suspected humpback chub captured in the Little Snake River, Colorado, on 25 May 1988. orado squaw fish collected, absence of other Col- orado squawfish collected near locations of radiotagged Colorado squawfish, subsequent contact of one radiotagged fish in Yampa Canyon at a known spawning area, and lack of collection of larval Colorado squawfish. However, these re- sults do not completely discount spawning of Col- orado squawfish in the Little Snake River. Occurrence of suspected humpback chub in the canyon section of the Little Snake River also ap- pears restricted to the spring runoff period. These chub may be seeking new habitats in which to live or spawn (since tuberculate fish were pres- ent). Suspected humpback chub observed in the Little Snake River during high water are prob- ably attracted to the relatively deep, turbulent eddies in the canyon and to warmer water. Humpback chub are typically associated with this type of habitat (Valdez and Clemmer, 1982). When discharge decreased, the suspected hump- back chub probably left the tributary because eddy habitat disappeared and was replaced by pool habitat. Photographs show that the sus- pected humpback chub collected in the Little Snake River canyon area were similar in ap- pearance to humpback chub collected in Cross Mountain Canyon on the Yampa River by Haynes (1980) and to humpback-like chub collected in Debeque Canyon on the Colorado River (Valdez and Clemmer, 1982). These three canyon areas represent the known upstream distributionallim- its for humpback-like chub in these rivers. Sus- pected humpback chub from these areas do not have the abrupt nuchal hump and fleshy snout found on larger specimens of typical humpback chub from Blackrocks or Westwater Canyon on the Colorado River (Fig. 2). These differences