FEEDING STRATEGY AND GROWTH OF CYPRINIDS IN THE LITTORAL-ZONE OF LAKEBALATON

The growth, diet and feeding strategy of five phytophil or phytolithop hil species of Cyprinidae from the littoral habitats of Lake Balaton w ere investigated by examining their scales and foregut contents. The r elationships between the total anterior radii of scales and the standa rd lengths were represented best by a power function for white bream B licca bjoerkna, and linear functions for common bream Abranis brama, r oach Rutilus rutilus and wild goldfish Carassius auratus gibelio, resp ectively. The backcalculated mean lengths for the first age groups of common bream, while bream and roach did not differ statistically from those obtained by direct observation on 0 group fish in late November 1995. Compared to other waters, common bream grows slowly, wild goldfi sh and roach rapidly, while the growth rate of white bream can be cons idered of medium speed in Lake Balaton. Common bream showed a generali zed feeding pattern, consuming mainly chironomid larvae, detritus and Corophium curvispinum. Roach showed a clear shift between specializati on for Dreissena and algae. Despite the dense population of D. polymor pha in the lake, the significance of the herbivorous adaptation of roa ch has not yet been made clear. Wild goldfish consumed mainly detritus but, in the open water region? it shifted to zooplankton. White bream preyed chiefly on D. polymorpha, but showed a mixed feeding pattern a nd utilized most of the available food resources. Carp had the most sp ecialized feeding strategy and preyed mainly on D. polymorpha. Accordi ng to the discriminant analysis, the five cyprinids exhibited signific ant food resource partitioning. (C) 1997 The Fisheries Society of the British Isles.