NadpisFunctional role of environmental stimuli for the spawning migration in Danube nase Chondrostoma nasus (L.)
Publication TypeJournal Article
Year of Publication2008
AutořiRakowitz, G, Berger, B, Kubečka, J, Keckeis, H
JournalEcology of Freshwater Fish

In spring 2004 and 2005, an online monitoring by horizontal split-beam hydroacoustics complemented by trap net catches and electro fishing was conducted to investigate the spawning migration of nase Chondrostoma nasus (L.) into the Fischa River, a tributary of the Danube River east of Vienna, Austria. Upstream-moving adult nase could be counted hydroacoustically based on their dominance (93%) of fish in the range 45-55 cm total length. Significant correlations were observed between the number of migrants and three environmental factors (water temperature, water level and turbidity), with special focus on their fluctuations. Thresholds of water temperature, water level and turbidity were revealed as general environmental cues on a seasonal scale. On a fine temporal scale, the fluctuations of the environmental factors over days, especially in the main river, represent relevant stimuli; they initiate and control the fine-scaled temporal pattern as well as the intensity of the spawning migration. In addition, a combination of increasing water temperatures and decreasing water levels, corresponding to the period after a flood peak, offers high predictability of favourable spawning conditions at the spawning place and acts as a stimulus for the right timing for upstream migration in Danube nase.