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. . Based on these two transects, the number of carp carcasses ranged from 137 to 178 per 100 m of single shoreline, or 274 to 356 per 100 m of both shorelines. This phenomenon was observed from the base of Big Drop 3 (RM 202.0) downstream to about Waterhole Canyon (RM 198.5); a distance of 3.5 miles or about 5,630 m. Assuming that the number of carcasses in the two transects reflected their abundance throughout the area, we estimate from 15,426 to 20,043 carp died in this area from winter ice conditions. The number of channel catfish carcasses in the same area is estimated at 113 to 450. These numbers may be considered high, since the transects were taken in areas with concentrations of carcasses. However, numerous such concentrations were noted. Also, the number of carcasses already washed away by the relatively higher water level is not included in our estimates. We have confidence that these estimates of fish carcasses are realistic. . . These are our first observations of this nature in Cataract Canyon, perhaps because it is the first time we have been through the entire area in the spring before runoff. It is possible that this phenomenon of "death by ice" occurs in other years, but the evidence is inundated and scoured by spring runoff. Nevertheless, what remains of the physical force wrought by the ice jams of this past winter indicates that certain species of fish (carp and channel catfish) are subject to substantial mortality from winte rice conditions. The mechanism which brought about their death is unknown, but it is speculated (based on observations during The winter Habitat study of Fishes in the Green River) that the fish which frequented shallow water were entrapped by the evergrowing ice and eventually became entombed. Death probably occurred from lack of oxygen and freezing of tissues. The entombed fish were then transported downstream as the ice became broken and jammed by fluctuating flows and air temperatures. The fish were finally freed from their icy caskets and deposited along the shoreline, in greater concentrations along the flat lowlying areas. . . . Yet, this does not fully explain the occurrence of these carcasses in a 10 to 15-m wide band above the current water level, considering that the flow on April 15, 1988, was 11,440 cfs--probably twice the volume of water during winter base flows. How, then did the fish and silt-laden ice end up 3 to 5 vertical meters above the current water level? Since this phenomenon was seen only from the base of Drop 3 to Waterhole Canyon, it is speculated that a huge ice jam occurred at Waterhole that backed up ice and water for 3.5 miles to the base of Big Drop 3. This is confirmed by the presence of huge 3 to 4-m high piles of floatsam entrapped in the shoreline rocks overlooking Big Drop 3. The silt band and fish were apparently deposited as the water subsided from breakup of the ice jam. . . DIFFICULTIES OR PROBLEMS . No major difficulties or problems were encountered during trip no. 2. A 16-foot Dory (whitewater wood boat) was used as a support craft, and it was noted that its capacity to carry cargo was limited. The craft was suitable for this short trip with the small crew, but would not be suitable to provide support for longer trips with more people. . 9