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1 they did not need to leave it often. Fish remained within this backwater during the entire winter and left it only a few times for only brief periods. Most embayment use was at RMI 81.1. This embayment remained relatively unchanged after ice-off and spring runoff. In addition to this embayment, one ' at IM 71.6 was used in Winter 2 and another at Government Bridge (MAI 98.8) was used early in both years. Fish used embayments throughout the winter, but they would occasionally leave to use run and other associated main-channel habitat. All pool habitat use was within a mile section at the Lily Park study site, a river segment characterized by eddy and pool habitat. This area has no backwater and very little embayment habitat available during law flow, winter conditions. All three fish (C87, C89, and coo) in this area used pool and occasionally run and/or eddy habitat during the winter. In areas where a variety of habitats was available, fish appeared to select certain habitat types over others. There was pool habitat within 0.3 mile of both the backwater (RMI 95.7) and the embayments (RMI 98.8, 81.1 and 76.2,) but no fish were observed to use these during the winter. Fish using main-channel habitats changed habitat more frequently than fish using off-channel habitats. Main-channel habitats may not provide as many of a fish's winter needs. Advantages to the use of off-channel (backwater and embayment) habitats may include: 1) low or zero velocity for energy conservation, 2) increased concentration of food, 3) easier identification of home range area thresh consistent visual or olfactory cues, and , 4) protection from moving frazil ice Off-charnel habitats may also provide other indirect benefits, e.g., increased oxygen and primary productivity. The lower flows present during Winter 2 either made these off-channel habitats less suitable or made main- channel habitats more acceptable. Squawfish evolved within a system that provided variability of flows between years. Natural yearly variability would be important to avoid food supply depletion during low-flow periods that would tend to concentrate prey within the main channel where less cover may be available. If low flows continued over several years, populations of prey species could be reduced since they would be subject to increased predation by the squawf1sh and introduce northern pike and have fewer highly productive feeding areas available during the winter. Predominant habitat used in the fall, 1987, was pool; followed by run, shoreline, and eddy. Backwater and embayment habitats were used the least in contrast to high use of these habitats during the winter. Most pool use was within the Lily Park Study Area where this habitat dominates over other types. Habitats used in the fall within the Maybell area were equally distributed among almost all habitat types (Figure 9). In the spring, eddy was the predominant habitat used followed by ' backwater and shoreline (Figure 10). Embayments were not used during this period probably since they tended to be flooded by the high floras. Run and pool habitats were used very little. Backwater habitat was used in all three , study areas. 24