Factors determining diet composition and food availability for bream, Abramis brama (L.), and white bream, Blicca bjoerkna (L.), in Włocławek dam reservoir

Wielgosz,S.; Tadajewska,M.

Factors determining diet composition and food availability for bream, Abramis brama (L.), and white bream, Blicca bjoerkna (L.), in Włocławek dam reservoir

Авторы

Wielgosz,S.

Tadajewska,M.

Издатель

Pensoft Publishers

Описание

Food composition of bream and white bream was studied in 1982-1984. Frequency of the rood components in the fish intestines pointed to the importance of Chironomidae, Copepoda, Mollusca and Macrophyta. Particular cohorts of the two fish species were characterised by considerable differences of the diet composition, both in the phonologic season and in particular years. White bream females fed more intensively than bream females and males of the same size. Statistically significant differences were found as to the consumption of chironomids by bream and white bream, size and length of the larvae consumed and intensity of feeding. Consumption of chironomids by the two euryphages increased with water temperature, reaching an optimum at 21°C. Prey density determined the food spectrum of bream and white bream. Both species grazed in the same areas but differed as to the intensity of sediment penetration and size of the chironomids consumed.