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35 years' data may be needed to raise the reliability of seasonal data to the excellent category for juvenile and adult fishes. The question remains whether lack of preferred habitat is a limiting factor for the rare fishes. For example, why were fewer juve- nile squawfish caught in the middle portion (Ouray-Sand Wash) of the study area than at either end? Was it because adequate habitat was not available and the fishes were therefore not present in that river reach, or were fish actually present but just not concentrated because of a lack of preferred habitat? McAda (personal communication, 1977) sampled from Sand Wash to near Green River in June, 1977, He found juvenile squawfish distributed throughout the entire area. The present study sampled the same area roore intensively in September, but found juveniles only in the lower por- tion. McAda caught most of the young squawfish in the mouths of small backwaters, which he indicated were fairly common. Few such areas were found during the present study in the upper part of Desolation, as the water had receded approximately 3 feet by September. In both cases, ju- venile density appeared to follow the availability of preferred habitat, This same pattern was noted in August in the Jensen-Ouray area, Juvenile squawfish were seldom caught in sections of the river that did not contain adequate habitat, i.e. backwaters of more than a foot in depth. Also, juvenile squawfish were often found in relatively large numbers in some backwaters. On two occasions, five juvenile squawfish were found in a backwater, and one time three were found. This evidence /