Dynamics of 24-hour Upstream Fish Migration in the Lower Course of Tundzha River, Southern Bulgaria, Based on a Fish-pass Video Monitoring

摘要

We tested a method for studying the species composition and dynamics of 24-hour upstream fish migration. We analysed a complete footage of 24-hour video recorded in the period April-May 2014-2016 in a fish-pass of a small hydroelectric power station constructed on the Tundzha River. Water flow, temperature and water levels were also registered, in order to establish the dependence of the main physical water parameters on the migration rate. Recordings from the fish-pass showed that migration occurred mainly during the daytime. For the whole period of the study, we registered 9745 fish migrating upstream (2380 individuals were identified at the species level). Seven fish species of the family Cyprinidae were recorded during the study at the pass. Dominant species were Chondrostoma vardarense (relative abundance 46.93%), Barbus cyclolepis (23.31%). Squalius orpheus (16.59%) and Vimba melanops (10.76%). The migration activity of V. melanops was positively affected by water level and water temperature and negatively correlated with water flow. For B. cyclolepis, water flow affected the fish numbers. For C. vardarense, the role of water temperature was more significant than that of water flow.