1977•Journal of the Fisheries Research Board of CanadaRequires access
Factors Affecting the Shift in Predominance from Eurasian Perch (Perca fluviatilis) to Roach (Rutilus rutilus) in the Kličava Reservoir, Czechoslovakia
Karel Pivnička, Miroslav Švátora
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Abstract
A shift in predominance from Eurasian perch (Perca fluviatilis) to roach (Rutilus rutilus) in the Kličava Reservoir in 1964, 10 yr after filling, was attributed mainly to a marked decline in the ratio of female to male perch spawners. The ratio was about 1:4 for perch and unity for roach. Fecundity of perch was about 25% that of roach which, together with the decline in spawning females, probably contributed to smaller year-classes. The decline in growth rate of perch in response to increasing abundance was greater than that for roach. Under equal environmental conditions, roach is also more productive than perch. Key words: Percidae, Perca, Rutilus, Kličava Reservoir, Czechoslovakia, shift in predominance, fecundity, sex ratio, methodology, growth–abundance relationships