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peak in early to mid-April (Figure 4). In May and June, water temperatures fluctuated 2-4 C while eventually warming up to 12-14 C. In July and August 1988-1989, water temperatures increased steadily to peaks near 25 C by the end of August. In 1991, peak water temperatures just under 25 C were not attained until late September. Water temperatures began to cool steadily in 1989 from mid-August through October. In 1988 and 1991, water temperatures did not start this steady decline until mid-September. Water temperatures in 1991 were consistently cooler from April through September than 1988-1989. Northern pike Five hundred fifty-six (556) northern pike in total were sampled from 1986 to 1991 (Table 1). Only seven northern pike were collected in 1986 and 12 in 1987 for the exclusive purpose of acquiring fish for radio tag implantation. In the following four years, more extensive sampling for northern pike in backwater habitats was initiated, and resulted in the capture of 91 northern pike in 1988, 175 in 1989,143 in 1990, and 128 in 1991. From 1992-1994, recaptures of northern pike tagged during the study provided seven additional data records (Appendix A, Table A-8). The most northern pike sampled per year consistently occurred in the Craig reach with the total being at least 140% greater than the other reaches. This was apparent even though this reach was not extensively sampled throughout as were the Juniper, Maybell and Lily Park reaches. Though only one sampling trip was made through Yampa Canyon in 1990, clearly fewer northern pike were present in this reach compared to the upper reaches in that year. Sampling effort in terms of number of backwaters sampled was dissimilar among the Juniper, Maybell and Lily Park reaches, and among the four years from 1988 through 1991 (see Table 18). Only in the Juniper reach and in 1991 was the sampling effort notably greater, but this had no apparent corresponding effect on fish sample totals by year or reach. Considering only the Juniper, Maybell, and Lily Park reaches due the extensive sampling that occurred in each, the number of northern pike captured in each year in these three reaches combined totaled 60 in 1988, 69 in 1989, 62 in 1990, and 72 in 1991. These sample totals show no correlation with the pattern of flow magnitude for the corresponding years. Numbers of northern pike collected in these three middle reaches differed in patterns over the four years. Northern pike numbers in the Craig and Juniper reaches peaked in 1989 after relatively low abundance in 1988, then declined consistently through 1991. Northern pike numbers in the Maybell reach appeared similar throughout the study period. In Lily Park, northern pike numbers declined notably from 1988 to 1989, but then increased in 1990 and again in 1991. As such, the patterns in northern pike numbers sampled among the river reaches show no consistent correlation with flow magnitude. An inverse correlation is apparent between northern pike numbers and flow magnitude in the Juniper reach; no correlation exists in the Maybell reach; and a positive correlation is apparent only in the Lily Park reach. It is uncertain whether the greater abundance of northern pike in the Juniper reach in 1989 and Maybell reach in 1988 contributed to the peak observed at Lily Park in 1991. 13