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ISMP backwater sampling evaluation We did not compare the relative efficiency of ISMP sampling to DMR sampling to detect presence of red and sand shiners and fathead minnows. This was because these abundant species were found in nearly every backwater sampled, regardless of the technique used. The lower effort ISMP technique tended to consistently underestimate the density of largemouth bass in backwaters compared to estimates derived from higher effort DMR sampling (Figs. 12 and 13). Averaged over 1997 and 1998, density of largemouth bass estimated from ISMP sampling was only 30 % (0 to 181 %) of the density of largemouth bass estimated by DMR sampling. In only 4 of the 30 backwaters where bass were found did ISMP density estimates exceed DMR estimates. For the 15 backwaters for which 95 % confidence intervals could be calculated for largemouth bass DMR density estimates, only one ISMP estimate fell within the confidence limits and the remainder fell below. Similar to largemouth bass, the lower effort ISMP technique tended to consistently 1 0 underestimate the density of green sunfish in backwaters compared to estimates derived from higher effort DMR sampling (Figs. 14 and 15). On average, density of green sunfish estimated from ISMP sampling equaled only 34 % of the density of green sunfish estimated by DMR sampling (0 to 260 %). In only 5 of 41 cases did the ISMP density estimate exceed that from DMR sampling. For the 22 backwaters for which 95 % confidence intervals could be calculated for green sunfish DMR density estimates, only three ISMP estimates fell within that interval. The ISMP abundance estimates for non-native cyprinids were generally less biased relative to DMR estimates than for centrarchid estimate comparisons. On average, density of red shiner estimated from ISMP sampling equaled 79 % of the density of red shiner estimated by DMR sampling (0 to 343 %, Figs. 16 and 17). Twelve out of 37 ISMP density estimates -15-