National Repository of Grey Literature 3 records found  Search took 0.00 seconds. 
Growth of Gymnocephallus cernuus, L. in freshwater reservoirs
Hubáčková, Zuzana ; Frouzová, Jaroslava (advisor) ; Jůza, Tomáš (referee)
Gymnocephallus cernuus (Linné, 1758) doesn't belong to economically important fishes, but it is very invasive and often compete with economically important fishes. Ruffe affects populations of the economically important species by competing with them for food or by eating their eggs and fry. That is the main reason why all information about its growth, establishing and development of new population, is needed. The occurance of ruffe is currently vast, but ruffe is not indigenous species in many places. It causes reduction of the biodiversity in these areas. Many scientists are motivated by this fact and they pay more attention to ruffe. Ruffe is not required/undesirable species so there is an effort to reduce them in many of its non-original areas. For these actions a lot of information about populations of ruffe is needed. To get quantitative data about entire population of fish it is necessary to know age structure of population and the range of growth - variations in particular age - categories. This work is divided into two parts. In the literary review I have concerned with various factors which influence growth of fish and ruffes' particularly. In the third chapter I am dealing with determination of fish age. The most attention is paid to determination of age by the way of otolites. In the...

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