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Posouzení možnosti reintrodukce lipana podhorního vysazením uměle odchovaných generačních ryb v předvýtěrovém období
PASTEJŘÍK, Jan
My bachelor s thesis deals with the possibility of reintroduction of the European grayling (Thymallus thymallus) into open waters by stocking artificially bred generation fish in their pre-spawning period. 3-4-year-old broodfish, bred in the pond Hulák in Prachatice, were used for the experiment. Then in the spring the fish were marked and stocked in the parts of FROV JU fishing ground, where fish were previously caught with electric aggregates and the local composition of fish stocks was examined. In the same way, a control catch was carried out also in the autumn - this time there was a main focus on the presence of the European grayling and juveniles. In addition, a follow-up section of the river (outside the experimental sections) was fished out and most fish were caught here. Based on the results of the monitoring, it can be said that in the section of the river where artificially bred generation fish were stocked at least partially successful natural spawning took place. Although the number of caught fish in the autumn was low (11 fish), this approach might be considered as promising in terms of the possibility of supporting the occurrence of the European grayling in open waters and suitable for further testing. Only 6 % of stocked generation fish were caught out 7 months after stocking. The size of these fish was practically the same as when stocked. In case of using this approach within the fishery management, it is necessary to stock generation fish no more than a few weeks before the expected spawning.

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