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Comparison of ichtyofauna in morphologically similar parts of trout zone of two rivers with different kind of management
ČEJKA, Jakub
The topic of this bachelor´s paper is comparison of biodiversity of fish community in morphologically similar parts of two South Bohemian rivers the Malše and the Blanice, which vary in the kind of fish management. There were chosen four parts of both rivers in the trout to the grayling zone, which were fished with a power generator in spring and autumn 2015. Fished fish, which are important for the fish management, were measured and weighed individually and then all the fish were given back to the parts. Gained data were processed. The parts, which were compared, are CHRO (freshwater fish protected areas), areas, where only original species are handled (brown trout (Salmo trutta m. fario, Linnaeus, 1758) and european grayling (Thymallus thymallus, Linnaeus, 1758)) and areas, where apart of original species rainbow trout popular with sport fishermen (Oncorhynchus mykiss, Walbaum, 1792) is handled. A similar trend of higher stability and condition of original species population in higher located parts of monitored fish district of both rivers was found out. There is a probable dependence of brown trout´s and grayling´s presence on handling of fries, which are heavily influenced by the presence of unoriginal species and sport fishing in the lower parts of the Malše river. It is possible to assume the existence of natural reproduction and subsequent sustainability of both species populations in the above-lying areas. The population of brown trout in the Blanice river can be judged like sustainable by itself in all the parts and influenced by undesirable fish species only in the lower parts. The presence of grayling in all the parts is probably dependent on fish migration from the lower part of the district and there is grayling only sporadic in the higher located parts.
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