THE HUCHEN (Hucho hucho) IN THE BALKAN REGION: DISTRIBUTION AND FUTURE IMPACTS BY HYDROPOWER DEVELOPMENT
The Huchen is one of the most enigmatic species of Europe's freshwater fauna. Historically, the species was wide‐spread across the entire Danube basin. Since the late 19th century, however, Huchen populations declined by two thirds and the remaining populations are now highly endangered by hydropower development. In this study, we review the actual occurrence of Huchen in the Balkan region. A total of 1842 river km supporting self‐sustaining populations of Huchen in the region have been identified, making it the global hot spot for the species. These populations are found in 43 rivers or distinct river reaches in Slovenia, Croatia, BIH, Serbia and Montenegro. About 65% of all Huchen rivers globally are located in these countries, highlighting the importance of Balkan Rivers for the survival of the species. The major threat to these populations is a massive hydropower development plan. A total of 93 dam projects were identified directly in river reaches supporting Huchen and a large number of additional projects are located in tributaries or headwater reaches upstream of Huchen habitat that will invariably degrade environmental conditions downstream. If these plans are carried out, we predict that at least 60‐70% of the Balkan population and about 35‐ 40% of the global population of Huchen would be lost with the remaining populations being small and severely fragmented and eventually no longer able to survive in the long term.