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1 t 1 t 1 t I Launch, and the lower 2.2 miles of the Gunnison River (the reach down- stream from the Redlands Diversion Dam). The search area was expanded upstream to the Price Stub Dam and downstream to the Utah state line when some fish could not be located in the immediate study area (Fig. 1). Radio-tracking was conducted from boats; however, immediately below the Price Stub Dam, searches from shore were necessary because of inaccessi- bility by boat. Locations of fish in the Colorado River were specified as river mile (RM) distance from the confluence with the Green River, and in the Gunnison River as distance from the confluence with the Colorado River. There is some confusion regarding river-milage at the Gunnison confluence; thus, a brief explanation of the circumstances there is warranted. Prior to this study, the Gunnison confluence (Gunnison RM 0.0) was considered to be at the site where the Gunnison first met the Colorado main channel at RM 170.2; the distance from there to the Grand Valley Diversion (CO RM 185.2) was therefore approximately 15 miles (thus the term '15-mile reach'). However, waters of the Gunnison actually first mix with those of the Colorado in a side channel at CO RM 171.0. Subsequent to the floods of 1983 and 1984, this Colorado side channel became the new main channel. The designated 'confluence' therefore shifted 0.8 miles upstream from the former site. The Gunnison mouth now occurs at CO RM 171.0 and the lower 0.8 miles of the Gunnison, as previously mapped, became part of the Colo- rado River. For the sake of consistency, however, we retained the origi- nal river-mile designations (Fig. 1). Thus, the Gunnison river now ends at GU RM 0.8 and not GU RM 0.0, and there are 2.2 miles of river between the confluence and the Redlands Diversion at GU RM 3.0. In addition, the '15-mile reach' is now 14.2 miles long. 5 1