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Eddies, like shorelines, were an important habitat type and also contained more adults than young or juveniles. This habitat was preferred by adult roundtail chub and adult channel catfish. Occasional shallow eddies (less than 1.5 ft deep) contained large numbers of young and juvenile roundtail chub and adult red shiner. Backwaters usually contained more young than either juveniles or adults. Small cyprinids (speckled dace, red shiner, fathead minnow, redside shiner, etc.) of all size classes, and young and juveniles of larger species such as flannelmouth sucker, bluehead sucker, and round- tail chub were commonly collected. Adults of species other than small cyprinids were uncommon. Pools and side channels were not important habitats for most species, based on total number of fishes collected, but appeared very; important to adult Colorado squawfish (analysis of all CRFP fish collec- tions for the Yampa River in 1981 there were 16 adult Colorado squawfish captured in pools). Also, 15 of 23 species in the Yampa River were collected in pools, though total numbers were low (Figure 9). Side channels were not present in the Little Snake River during sampling. In the Green River, side channels were primarily in the upper Island Park (Stratum 2) area. Although side channels were found in the Yampa they contained only a moderate number of fish species (Figure 9). Riffles were most important for adults of the two native suckers and for speckled dace and mottled sculpin. Nine of 11 species collected in the Little Snake River were found in this habitat as were 12 of 19, species in the Green and 11 of 23 in the Yampa (Figure 9). Main channels and runs contained 16 and 19 species, respectively in the Yampa River, but contained few species in the Green River. This apparent difference was due to absence of sampling in such habitat in Green River rather than any actual difference in habitat utilization by fishes. Rare Fishes The major objective of the Yampa River fishes study-was to deter- mine the biological significance of the Yampa, upper Green, and Little Snake rivers to endangered Colorado River fishes including the Colorado squawfish (Ptychocheilus lucius), humpback chub (Gila cypha)'and bony- tail chub (G. elegans . Although the razorback sucker (Xyrauchen texanus) is not a federally listed species, it has been proposed for listing twice by the USFWS and is on the Colorado state endangered species list. Individuals of all but bonytail chub were collected in the present study. General distribution information for rare fishes was presented in the preceding section on the habitat and relationships of all fish species. Specific information about movement and the life history of rare fishes is presented in this section. 46