ABSTRACT
This chapter describes the development, validation, and testing of a metric-rich coldwater Index of Biotic Integrity (IBI) based solely on fish assemblages and designed for use within the upper midwestern United States, specifically the states of Minnesota, Wisconsin, Michigan, and Indiana. The coldwater IBI was used to compare stream sites with different types of salmonid assemblages to determine whether the type of assemblage present was related in any way to biotic integrity. Coldwater streams in regions lacking a warmwater fish fauna, or those with steeper gradients, might not display an increase in species richness with impairment. Abundance or catch-per-effort metrics are common in most versions of the IBI because degraded stream sites generally are expected to yield fewer fish than are higher-quality sites. Both coldwater and warmwater fish abundance metrics were able to discriminate between impaired and reference sites, and both responded to impairment as expected.
