Riffle spawning white bream Abramis bjoerkna (Cyprinidae) in a regulated river‐a case of unsuitable habitat choice?

Abstract

The choice of spawning sites, winter habitat and longitudinal distribution of white bream Abramis bjoerkna was studied in an epipotamal river. Spawning was observed exclusively in riffles habitats. Adults (in winter) and age 0+ fish (throughout the year) were found only in backwaters and at low abundance. Adults were distributed in a longitudinal cline resulting from the occurrence of only three suitable backwaters for over‐wintering in the downstream part of the river. The abundance of 0+ age fish and the age structure of the adult stock suggest that white bream only recruit irregularly in the River Sieg.

Key words:

• Cyprinidae
• Habitat choice
• Spawning behavior