Application of fish-based index of biotic integrity to assessment of aquatic resource of Mae Ngad Somboonchon Reservoir, Thailand

A fish-based index of biotic integrity was applied to the assessment of aquatic resource of Mae Ngad Reservoir, Chiang Mai, Thailand. Surveys of the fish assemblage were conducted in 2002, 2004 and 2019. Eighteen metrics were designed and applied, viz. species richness, diversity index, dominant index, hybrid species, native species, alien species, omnivores, insectivores, carnivores, pelagic species, water-column species, bottom species, rocky-and-stone species, sandy-and-gravel species, silty-to-muddy species, intolerant species, tolerant species and anomalies. Scores for each of the 18 metrics were summarised to provide an index value for each fish community sample, which can be used to determine the relative health of the site. In 2019 it was found that the fish data consisted of 10 families and 20 species. The overall fish-based index for Mae Ngad Somboonchon Reservoir in 2019 was 38, indicating fair biotic integrity.