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' the fall and relocated apparently recovered from any disorienting effects and were subsequently monitored through each winter. After ice formation, in late November and early December, fish stayed within very specific river reaches (home sites or averwintering areas). Fish did not move outside of their overwintering areas until ice-out. In addition, fish used very specific areas within a given habitat. They often stayed in these areas Uumghout the winter or repeatedly returned to then after using other areas for a short time. This suggests homing and fidelity to very specific overwintering habitats. During the period of ice cover, movement averaged 0.3 mile each year with ranges of 0.0 - 1.1 miles in Winter 1 and 0.0 - 0.5 mile in Winter 2 (Table 5). The three fish that used the backwater at RMI 95.7 consistently utilized that habitat on every monitoring trip in Winter 1, and one fish (A10) used it both winters. In winter 1, five fish used the embayment at RC 81.1 in conjunction with main-channel habitats; only B09 used t b aymen it each trip. The other four fish (A09, B08, B10, and B11) used the em with occasional forays into the main-charnel pool and run area at RMII 81.4. Fish B11 returned and used this embayme t, in the fall and winter during the second year of the study. Fish in the Lily Park area tended to remain within a given pool throughout the winter, but there was some movement between pools within the river reach. All other fish were found in main channel habitats or shoreline; these fish tended to move the greatest such as eddy run , , distance during the winter. During Winter 2, A91, A70, and C91 could not be located during the winter period but were found after ice Off. Ice break-up (ice-off) occurred on March 7-9, 1987 and March 19-22, 1988. Radiatagged fish were located downstream of over-wintering areas within a week after ice-off both years, except the four fish (B08, B09, B11, and A09) that were within the enbayment at RMI 81.1 in Winter 1. In Winter 1, all fish in the backwater (RMI 95.7) moved out during ice-off. This would be expected since the backwater was dramatically changed by the hydrologic events of ice-- off and the resulting scouring and flooding of the dislodged ice and water. ' Downstream movement of 17 fish averaged 0.8 miles for both years. One other fish (BB7) was located 7.4 miles upstream after ice-off. It is likely that this fish did the majority or all of this movement after the ice-off event. Eight transmitters in fish from the first year were operable during the fall of 1987. All eight of these fish were located within the same study site in which they were tagged during fall 1986. Three additional fish were tagged during 1987 in the Lily Park Study area for fall monitoring. Average movement ' of these eleven fish during the fall from September 21 through November 20, 1987 averaged 0.9 mile and ranged from 0.0 to 4.4 miles. Six fish moved between 0.1 and 0.7 mile and three showed no change in river mile location ' during the fall (Table 5). Movement during ran-spawning times was greatest in the spring, averaging 6.5 miles (range 0.0 - 43.2 miles) in spring 1988 with most fish mowing in a ' downstream direction. No data were collected in spring 1987. Fish A00 moved 43.2 miles in April 1988 (24.6 miles occurred in a 2-day period from April 19 to April,21). The next farthest-moving fish moved only 8.5 miles. If A00 is not considered in the calculation, the average spring movement was 2.9 miles for the mining 10 fish. Two fish (C00 and C87), in addition to moving downstream, moved up into the Little Snake River, 1 and 6.7 miles respectively, in may and June, These movements were probably in response to increased flows which altered habitats that had been suitable in the winter. Fish probably moved to habitats more suitable for high water conditions. ? ,s 1