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DRAFT25 In order to establish that the backwater fish community is adequately represented by ISMP sampling, a separate Sampling Efficiency study was performed. Sampling efficiency may have been affecting our ability to analyze the data for habitat preferences. Acapture-removal study was conducted using seines in backwaters in the Green and Colorado Rivers in 1994 and 1995 in four sampling trips. A portion of each backwater was blocked off and all fish within removed and counted in a series of 10 seine hauls. The first seine haul was comparable to a standard ISMP seine haul. A thorough treatment of the study is given in the appendix. Briefly, the results of the sampling efficiency study indicate that ISMP sampling is representative of the more common species collected in the backwater, including Colorado squawfish. Colorado squawfish, if present, were almost always collected in the first seine pass. Relative abundance of common species in the first seine pass was not significantly different from that of the total number offish present, except for channel catfish which were consisterrtly underestimated. Significantly more species were present in total than in the first seine pass, but the additional species were usually represented by a single individual. There were no significant differences in capture probability of Colorado squawfish or ~o~..-°~ b"v other species lei b~t~r types (based on seining difficulty due to substrate types, not n habitat). Significance was low because there was a great deal of variation in capture probabilities .g be nand within all types of backwaters. The variation in sampling is not an artifact of sampling efficiency. Although we have shown that ISMP is representative of the fish community in squawfish- preferred habitats, this effort did not address the small fish community outside oflow-velocity habitats. In addition, because the diversity offish is lower in the Lower Green River nursery -25-