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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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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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Age structure and growth of wild brown trout in relation to population density and habitat quality
Závorka, Libor ; Slavík, Ondřej (advisor) ; Matěna, Josef (referee) ; Reichard, Martin (referee)
Brown trout Salmo trutta L. is a fish species with high socio-economic value, which is favourable among anglers and a successful invader worldwide. The aim of this thesis is to explore environmental factors affecting body growth and survival of brown trout with emphasis on density dependent selection in juvenile life stages. This thesis is specifically focused on: (1) effect of population density on growth and survival with respect to a dynamic of a local group of individuals (papers I and II); (2) effect of inter-individual differences in behaviour on the relationship between individuals life-history traits and available resources (papers III and IV); (3) link between demo-genetic structure of population and growth and mortality rates of individuals (papers V, VI and VII). Datasets for this thesis were collected during a long-term mark-recapture study on wild brown trout population (2005-2011) in the catchment of the Otava River in Šumava National Park (Czech Republic) and a set of field and laboratory studies conducted on wild populations in streams on west coast of Sweden. In accordance with some previous studies, this thesis showed that growth of juvenile brown trout is negatively affected by population density. Nonetheless, this thesis reveals that the negative effect of density dependent...
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Age structure and growth of wild brown trout in relation to population density and habitat quality
Závorka, Libor
Brown trout Salmo trutta L. is a fish species with high socio-economic value, which is favourable among anglers and a successful invader worldwide. The aim of this thesis is to explore environmental factors affecting body growth and survival of brown trout with emphasis on density dependent selection in juvenile life stages. This thesis is specifically focused on: (1) effect of population density on growth and survival with respect to a dynamic of a local group of individuals (papers I and II); (2) effect of inter-individual differences in behaviour on the relationship between individuals life-history traits and available resources (papers III and IV); (3) link between demo-genetic structure of population and growth and mortality rates of individuals (papers V, VI and VII). Datasets for this thesis were collected during a long-term mark-recapture study on wild brown trout population (2005-2011) in the catchment of the Otava River in Šumava National Park (Czech Republic) and a set of field and laboratory studies conducted on wild populations in streams on west coast of Sweden. In accordance with some previous studies, this thesis showed that growth of juvenile brown trout is negatively affected by population density. Nonetheless, this thesis reveals that the negative effect of density dependent...
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Age structure and growth of wild brown trout in relation to population density and habitat quality
Závorka, Libor ; Slavík, Ondřej (advisor) ; Matěna, Josef (referee) ; Reichard, Martin (referee)
Brown trout Salmo trutta L. is a fish species with high socio-economic value, which is favourable among anglers and a successful invader worldwide. The aim of this thesis is to explore environmental factors affecting body growth and survival of brown trout with emphasis on density dependent selection in juvenile life stages. This thesis is specifically focused on: (1) effect of population density on growth and survival with respect to a dynamic of a local group of individuals (papers I and II); (2) effect of inter-individual differences in behaviour on the relationship between individuals life-history traits and available resources (papers III and IV); (3) link between demo-genetic structure of population and growth and mortality rates of individuals (papers V, VI and VII). Datasets for this thesis were collected during a long-term mark-recapture study on wild brown trout population (2005-2011) in the catchment of the Otava River in Šumava National Park (Czech Republic) and a set of field and laboratory studies conducted on wild populations in streams on west coast of Sweden. In accordance with some previous studies, this thesis showed that growth of juvenile brown trout is negatively affected by population density. Nonetheless, this thesis reveals that the negative effect of density dependent...
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Age structure and growth of wild brown trout in relation to population density and habitat quality
Závorka, Libor
Brown trout Salmo trutta L. is a fish species with high socio-economic value, which is favourable among anglers and a successful invader worldwide. The aim of this thesis is to explore environmental factors affecting body growth and survival of brown trout with emphasis on density dependent selection in juvenile life stages. This thesis is specifically focused on: (1) effect of population density on growth and survival with respect to a dynamic of a local group of individuals (papers I and II); (2) effect of inter-individual differences in behaviour on the relationship between individuals life-history traits and available resources (papers III and IV); (3) link between demo-genetic structure of population and growth and mortality rates of individuals (papers V, VI and VII). Datasets for this thesis were collected during a long-term mark-recapture study on wild brown trout population (2005-2011) in the catchment of the Otava River in Šumava National Park (Czech Republic) and a set of field and laboratory studies conducted on wild populations in streams on west coast of Sweden. In accordance with some previous studies, this thesis showed that growth of juvenile brown trout is negatively affected by population density. Nonetheless, this thesis reveals that the negative effect of density dependent...
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Reciprocal predation between non-native crayfish and salmonids Who eats whom?
MÜLLEROVÁ, Lucie
Signal crayfish (Pacifastacus leniusculus) is important invasive species in European freshwaters. Its influence on other freshwater organisms is well known from the literature, as well as direct and indirect impact on fish assemblages. This work was focused on the experimental evaluation of non-indigenous signal crayfish as a predator of salmonids compared to indigenous noble crayfish (Astacus astacus). Moreover, the possible importance of young-of-the-year signal crayfish as a prey for salmonids was assessed. There were carried out experiments using eggs and hatchings of grayling (Thymallus thymallus) as a prey for adult and subadult specimens of both, signal and noble crayfish. Next experiment used young-of-the-year signal crayfish as a prey for young-of-the-year of brown trout (Salmo trutta). Results showed that the danger of signal crayfish for grayling eggs is slightly higher. However, detected differences were surprisingly lower and in the majority of parameters even insignificant. In the case of grayling hatchings, was not detected any significant difference at all. The abilities of both tested species to prey on eggs and hatchings are therefore very similar, comparable. Even so, the effect of signal crayfish can be importantly higher in natural conditions because of its more dense populations, higher growth rate and fast maturation. In accordance to our findings, it is evident that brown trout has no so high effect of crayfish juveniles compared with crayfish effect on salmonids early developmental stages. Crayfish are therefore more likely able to limit salmonids than conversely.
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Zhodnocení trendu vývoje úlovků lososovitých ryb a lipana podhorního ve vybraných pstruhových revírech řeky Svitavy
Polívka, Lukáš
Bachelor's work is targeted on factors affecting number of fish society on trout fishing areas, mainly of salmonids and grayling. Further more work is targeted on evaluation of anual catches of fish listed below on trout areas Svitava 3,4 and 5 in last 15 years. This results will be compared to fishing pressure on monitored areas with level of releasing of fis listed below. For evaluation of catches, fishing pressure and level of released fish was used evidence of trout kinds fish areas MRS in Brno. Results are showing, that the largem number of catches in last 15 years are in Svitava 3 area, which i also under the biggest fishing pressure. On the contrary the most fish released were in area Svitava 5. Enviromental factors in Svitava river are distictly better than in 1989. In this improvement are involved many closes of troubled facilities and also wastewater treatment plant.
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