The spring and summer nutrition of the 300-500 g pike-perch (Lucioperca lucioperca l.) in Lake Balaton in 1968. I. Data bearing relation to the nutritional conditions proceeding the destruction of fish in 1965

Biró, Péter and Elek, László (1969) The spring and summer nutrition of the 300-500 g pike-perch (Lucioperca lucioperca l.) in Lake Balaton in 1968. I. Data bearing relation to the nutritional conditions proceeding the destruction of fish in 1965. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 36. pp. 135-149. ISSN 0365-3005

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Abstract

Fish remains found in the stomachs show the following order of frequency considering only the most important species: Lucioperca lucioperca > Acerina cernua > Alburnus alburnus, this sequence was displayed in 1965, however, in the years 1967 and 1968 the above order was reversed. Significant seasonal and regional fluctuations have been observed in the consumption of occasional species for feeding. According to the number of fish found in the stomachs the most frequent type was which consumed only one specimen (45.6%), two specimens (30%) while the individuals consuming 3 specimens were scarce (12.5%). More than three specimens, consumed by one pike-perch, gave only 5.6-0.1%. According to the evaluation of the weight of the consumed food 46% of the feeding pike-perch has taken 1-5 g, 30.9% 6-10 g and only 18.3% has taken 11-20 g of food. The respective values of food coefficient of these weight data are extremely low: only 3.9-0.2% of the pike-perch has reached a food coefficient higher than 5.4. The proportion of feeding pike-perch and pike-perch with empty stomach from 1965 shifted to the benefit of the feeding type, however, the quantity of available food decreased, compared to the value ten years ago. The number of the feeding animals is not in proportion with the consumed food quantity in spite of the fact that a decrease was observed in the number of the pike-perch population and the feeding conditions of the fofourth grade pikeperch in Lake Balaton have not improved considerably.

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