Water quality improvements following political changes, enhanced fish communities, and fisheries in the Czech Republic

Political and economic changes in 1989 in the Czech Republic (a part of the former Czechoslovakia) led to the collapse of several large industries (e.g., sugar refineries, paper mills), which utilized old technology that negatively affected water quality. Simultaneously, the financial resources available to the agricultural sector were considerably reduced, which was manifested by a decrease in the use of fertilizers and pesticides. In addition, old waste-water treatment plants were modernised and new ones constructed. Together these activities substantially increased the water quality of Czech rivers. In the River Morava (Danube basin), one of the largest rivers in the Czech Republic, we observed substantial changes in the fish community over this period. Fish species richness has increased continuously over the last 10 years and has almost reached the situation that existed 100 years ago. Anglers' statistics also document an increase in fish catches. Improvements in water quality and the absence of formerly regular seasonal acute fish poisoning have come about despite the physical structure of the river remaining unchanged. Further enhancement measures will necessitate river system revitalization measures, such as longitudinal reopening of the river channel and reconnection of the main channel with its floodplain and associated water bodies.