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Abundance reductions for many native fishes between the 1994 to 1996 and 2002 to 2004 sampling periods led us to examine if seasonal differences in catch rates or differences in environmental factors such as turbidity influenced capture rates: Changes in seasonal capture rates among the two sampling periods were postulated because two of the four sampling trips in the 1994 to 1996 period were in spring and one in each of summer and autumn. Conversely, in the 2002 to 2004 period only summer and autumn electrofishing sampling (one per year, total of three summer and three autumn samples) were conducted. Thus, fifty percent of samples were taken during spring in the 1994 to 1996 period, a time of relatively low capture rates, and 50% of samples in the 2002 to 2004 period were taken in the autumn season, a time of relatively high catch rates. Because of these differences, we believe that relatively low catch rates in the recent period were not a function of differences in sampling seasons among the studies. Differences in the two periods may even be conservative because more samples in the 1994 to 1996 period were collected in spring when capture rates were relatively low. We also do not think catch rate differences were due to crew or gear differences, because similar personnel, gear, and methods were used in each of the two time periods. Comparison of seasonal differences in catch rates from the 2002 to 2004 period suggested CPUE was substantially higher in autumn than in summer for most species. Higher capture rates in autumn suggested that monitoring sampling for most species may be best conducted at that time. A negative aspect of autumn sampling is that detection of ripe Colorado pikeminnow would not be possible. Higher species richness in autumn electrofishing samples from 2002 to 2004 is additional support to conduct adult fish monitoring in autumn. We expected capture rates of fish to decline when water was turbid compared to when water was clear, because fish presumably would be more difficult to see and capture. When all available data in both 1994 to 1996 and 2002 to 2004 periods was analyzed, we found this was not true because capture rates were similar in turbid and clear water. Comparison of capture rates for some of the more common species (brown trout, flannelmouth sucker, and bluehead sucker) and ones of particular interest (Colorado pikeminnow, smallmouth bass) were also similar in turbid and clear water. This suggested that monitoring sampling should not be 39