Longitudinal zonation of the river based on the presence of fish species (Case study: Jajroud river)

The physical, chemical and biological characteristics of rivers are gradually changed from upstream to downstream of the river, and one of the obvious consequences of these changes is the creation of limited and specific reaches along the river for fish species. In the present survey, the Jajroud river was sampled and surveyed from the upstream tributaries to downstream using the Huet classification method. In this study, 783 specimens of fish belonging to 3 families, 8 genus and 10 species were caught. The cyprinidae with 54.4% and salmonidae with 4.3% were the highest and the lowest percentages of native species, respectively. The results showed three major zones from four zones of the Huet's classification including trout, barbel, and bream. In addition, four distinct local zones were recognized along the river based on the presence of fish species. The trout zone with a length of less than 10 km and is of important conservation and management measures. This research addresses the longitudinal reaches of the Jajroud river that helps to conduct future ecological research in this river and also could  be an onset of using this method in other rivers in Iran to identify the longitudinal zones and the distribution pattern of fish fauna.