Development of the fish assemblage on the river Kněhyně with focus on the revitalization section in PLA Beskydy (Czech Republic)

Abstract

Most rivers and even streams in Europe are regulated. Current ways of revitalization aims opposite the former practice. There is still a lack of information about the impact of a revitalization on ichthyofauna. The River Kněhyně (right tributary of the Rožnovská Bečva River) is located in the Protected landscape area Beskydy in the northeastern part of the Czech Republic. In 1997, a massive flood hit the Kněhyně catchment area. In 2003-2004, 300 m section of the river was revitalized. The aim of this study was to evaluate to development of the fish assemblage on the River Kněhyně with focus on the revitalization section. The study was conducted in five locations in the River Kněhyně. Alpine bullhead and Brown trout were captured by twopass electrofishing using a backpack electroshocker straight DC], Bednář, Czech Republic). Results of the work can be summarized as follows: (1) The revitalization did not influence species diversity of ichtyocenosis (Alpine bullhead -Cottus poecilopus and Brown trout -Salmo trutta m. fario); (2) During the research, the highest abundance and biomass of brown trout was found in the revitalized section; (3) The highest historical abundance and biomass of alpine bullhead was recorded in the upper part of the revitalized section. The lower part of the region was not significantly different from other sites.