(Doledec and Statzner, 2010). In North America, Karr (1981)
initiated the first studies based on the multimetric index (MMI)
approach, in which attributes of fish assemblages (metrics related
to species richness and composition, trophic composition,
abundance, and health status) were used to evaluate anthropo-
genic pressures on a stream and its watershed ecosystem. Metrics
are scored according to reference conditions