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Adaptibilita lipana podhorního (Thymallus thymallus) po vysazení v závislosti na technologii odchovu
Pospíšil, Kryštof
The diploma thesis is focused on the adaptation of Europen grayling after stocking. Within of this diploma thesis, 3 different technologies of breeding were compared. The group marked grayling stock was monitored at trout fishing ground the Oslava 6 at 4 locations in 2021-2022. Recapture of marked grayling was carried out using electrofishing and fishing with an artificial fly (fly-fishing). During the catches, were acquired the physical-chemical parameters of the water and the length-weight parameters of the fish caught, for the subsequent determination of the nutrition coefficient according to Fulton and the AT coefficient according to Spurný (2000). The abundance and biomass of the fish community was subsequently determined from the recorded data. As part of electrofishing, zoobenthos was collected from all localities, and after laboratory determination, its abundance and biomass were examined. The degree of adaptation of stocked grayling was assessed from the percentage representation of the food component (natural food) from the stomach contents. Stomach contents were collected by a non-lethal method using a stomach pump or a modified syringe. The results show that the stock from each technology of breeding has adapted to the natural food offer, but the amount of data obtained may distort the results.
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Ellimination of unwanted fish species from dam reservoirs - Possibilities, efficiency and economic evaluation.
Jůza, Tomáš ; Blabolil, Petr ; Čech, Martin ; Draštík, Vladislav ; Holubová, Michaela ; Hůda, J. ; Kočvara, Luboš ; Kolařík, Tomáš ; Muška, Milan ; Peterka, Jiří ; Prchalová, Marie ; Říha, Milan ; Sajdlová, Zuzana ; Tušer, Michal ; Vašek, Mojmír ; Vejřík, Lukáš ; Kubečka, Jan
spontaneous development of populations and the influence of human interventions. For situations where a certain part of the fish population needs to be caught, within the project 'Biomanipulation as a tool for improving the water quality of reservoirs', we tested the available approaches in terms of their effectiveness and difficulty. The target species of catches were mainly cyprinid fish (bream, bleak, roach, rudd, white bream), which feed mainly\non zooplankton and tend to form very large populations. Among the most effective methods of catch during spawning are catches using electrofishing boats and fyke nets. In the non-spawning period, it is possible to carry out mass catches using trawl nets. Catches are effective both before spawning (in April) and during the summer. However, with repeated catches in the same places, their effectiveness decreases as a result of the fish being spooked. The efficiency of the catches partially improves again if the catches are repeated with a break of approximately 1–2 weeks. Catches also vary according to the stocking density of a given water body. With effective catches, the cost of catching 1 kg of fish is in the range of CZK 15–50.
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Methodology of predatory fish quantification in reservoirs and lakes.
Blabolil, Petr ; Jůza, Tomáš ; Vašek, Mojmír ; Peterka, Jiří
The publication contains an evaluation of surveying 36 reservoirs and artificial lakes in the years 1985–2020 in different parts of the Czech Republic by four sampling methods, which are further divided according to the sampling environment, daily periods and targeted age groups of predatory fish. The methods are gillnets, seines, trawls and continuous boat electrofishing. The catchability, standardized and relative abundance of asp, pikeperch, pike and catfish are evaluated. Based on these data, the reader can decide which method to use to detect a particular predatory species and compare the results with the situation in other localities.
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