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Comparision of rate of pike and pike perch cannibalism in first year of life
SVATEK, Petr
Abstract Larvae of perch (100-200 thousand per ha) were planted into the ponds Bejkovna (1,33 ha) and Kamenný (1,54 ha). Larvea of pikeperch (150 - 300 thousand per ha) into the ponds Hejškův (0,88 ha) and Hadač (2,7 ha). Pond Bagr was used such as an additional data source. The aim of this study was Comparision of rate of pike and pike perch cannibalism in first year of life. There wasn?t observed cannibalism and different sizes of perch individuals in the ponds Bejkovna and Kamenný. Total length (TL) of the fish was 50,5 ? 2,85 mm in the pond Bejkovna and 41,58 ? 1,56 mm in the pond Kamenný at the end of observed period. Average growth rate was 0,86 mm/day in pond Bejkovna and 0,7 mm/day Kamenný. There was also no cannibalism by the perch (TL = 57,2 ? 1,34 mm) from the pond Bagr. It was possible to observe few individuals of roach (Rutilus rutilus) in the digestive tract. The level of cannibalism was 23 % in the pond Hadač and also in the pond Hejškův. The average TL was 31,59 ? 3,89 mm (average growth rate 0,9 mm/day) in the pond Hadač at the beginning of June and 26,83 ? 2,51 mm (average growth rate 0,77 mm/day) in the pond Hejškův. The average TL was 48,7 ? 10,04 mm in the pond Hadač at the end of June. There was observed cannibalism in the pond Hadač at the beginning of the June and also at the end of this month. TL of prey fish was 66,1 and 61,6 % of cannibals TL. There was observed cannibalism in the pond Hejškův until the mid of September. The average TL was 140,6 ? 35,4 mm here and cannibalism was observed in 23 % of cases. TL of prey fish was 54,9 % cannibals TL. The most important thing of the monoculture rearing of perch and pikeperch is sufficient amount of food. This is especially true in the case of pikeperch. Key words: Cannibalism, pike perch, perch
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