A statistical review of sampling of fishes in the LTRMP Gutreuter, S. 1993. A statistical review of sampling of fishes in the Long Term Resource Monitoring Program. National Biological Survey, Environmental Management Technical Center, Onalaska, Wisconsin, December 1993. EMTC 93- T004. 15 pp. (NTIS #PB94-150828) ABSTRACT Monitoring programs for freshwater fish are commonly rely on fixed-site sampling, wherein non-randomly selected permanent stations within particular habitat types are sampled repeatedly through time. The Long Term Resource Monitoring Program fish sampling sites were selected based on subjective judgments that particular sites were representative of their habitat type. Unfortunately, fixed-site sampling cannot produce data that can be used to verify whether specific sampling sites are truly representative of habitats. Because fixed-site sampling designs are not spatially randomized, they cannot support statistically valid conclusions about patterns or trends in the larger study area. Fixed-point sampling designs can only be used to make inferences about the specific set of sampling sites. Fixed-site sampling is often justified based on the supposition that, for example, fish catches are much more variable among different site locations than within any specific site. Although this supposition is commonly accepted, it has not been critically tested. To examine this supposition, I partitioned the 1990 LTRMP fish data into unique combinations of species, study reach, sampling gear, habitat class, and time period and estimated within-site and among-site variance from each partition. Among-site variation was actually less than within-site variation in over 50% of the partitions. The hypothesis that among-site variation was less than or equal to within-site variation could not be rejected. The LTRMP therefore adopted a stratified random fish sampling design in 1993. KEYWORDS sampling, variance components, fish, monitoring, rivers, statistics, randomization, design