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r 23 when it was most prevalent in the river, squawfish actually appeared to be attracted to it. Habitats free of frazil were nearby but refuge was not sought there. Frazil ice did not occur in backwaters, embayments and eddys. It is possible that the food items contained in the frazil were used directly by the squawfish and/or possibly squawfish were attracted to other smaller fish which were feeding on aquatic insects suspended in the frazil. Eddy habitat was utilized by radiotagged squawfish 8.7% of total observation hours (Table 5). Fish B7 and B10 used eddys extensively throughout the winter. The typical appearance of eddy habitat at ice-over is portrayed along the right side of Figure 7. This area at RMI 76.2 was used by B7. Eddy habitat provided the greatest depth observations (8.8 feet) during the study. The velocity range was quite narrow between -0.2 to 0.3 feet/second. Silt was the predominant substrate type. Reverse or revolving water currents typified eddy habitats. These currents are usually caused by projections of rocks jutting out from the shoreline. Other habitats used by radiotagged squawfish throughout the winter included shoreline (2.7%) and side channel (1.2%). 10 Survey potential Because of their easily identifiable nature at initial ice formation, major habitats used by squawfish during the winter could be effectively surveyed. Areas similar in appearance to those presented in Figures 4-7 could be identified from aircraft or boat at initial ice formation. Later, these areas could be further examined for the appropriate range of depth, velocity, and substrate parameters determined during winter radiotelemetry studies. A method is needed to determine percent habitat change--as a result of changes discharge. To do cura a method of relating water surface elevation of discharge must be established during the winter months. Diel comparisons The 24 hour data set was used for comparing habitat measurements between different daily time periods since the data within it was evenly distributed through the four time periods. The time periods analyzed where; morning (0600-1200 hrs), afternoon (1200-1800 hrs), evening (1800-2400 hrs), and night (2400-0600 hrs). Depth, velocity, substrate, and habit=t paramatPrc appeared aimiLar between all four time periods. Mean water depths ranged from 2.25 to 2.68 feet (Table 9 and Figures 8-11). Velocity at 0.6 depth was just under 0.2 feet/second for each of the periods (Table 10 and Figures 12-15). Gravel- gravel was the predominant substrate in each period, however less frequently used substrate types differed in each time period (Figures 16-19). Backwater was the predominantly used habitat type followed by run in all periods (Figures 20-23). Depth There was ice cover over all measured depths during all trips except the last (March 16 - 21), when the river was ice free. All depths reported are the amount of ice-free water under the ice (Figures 2a and 2b). Mean water depth in the main hole was 2.4 feet with a range between 0.5 and 8.8 feet 0