Alternative Fish Assemblage Sampling Methodologies for Standard IBI (MMI) Metrics in Lakes, Rivers & Streams: Examples from Six Continents

Increasingly, fisheries biologists are being tasked with assessing entire fish assemblages at many sites because of the value of those assemblages in making regional and national ecological assessments.  Whether or not those assessments are based on species richness or some sort of fish assemblage index, it is important to determine cost-effective standards regarding sampling gear, site extent, number of individuals sought, study designs, and number of sites sampled.  In this presentation, we describe sampling gears used for developing multimetric indexes by scientists in 10 nations and 6 continents. We then use results from sampling effort studies conducted in temperate (Pacific Northwest) and tropical (Brazil) systems to document feasible approaches.  Depending on water body conditions and objectives, we found that electrofishing or nets, site extents of 40 to 100 wetted channel widths, >150 individuals, probabilistic study designs, and 15 to 40+ sites per reporting unit were appropriate for making assessments.