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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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The Sexual Segregation of fish from family Cyprinidae in the Řimov Reservoir
Žák, Jakub ; Prchalová, Marie (advisor) ; Čech, Martin (referee)
The sexual segregation, defined as different use of space by sexes is widespread phenomenon in the animal tree of life. As a result of segregation there is a different use of resources such as habitat, prey items or different threat by predation. Nevertheless it is not well studied in fish taxa except in marine environment. The common and widespread freshwater species such as a bream (Abramis brama), a bleak (Alburnus alburnus) and a roach (Rutilus rutilus) so far have not never been studied from the perspective of sexual segregation too. This thesis aims to examine the sexual segregation of these species and to test premises of sexual segregation such as sexual size dimorphism, age composition and differences in food. Afterwards the different space use of sexes in the Římov reservoir was tested. The gillnet sampling was used to collect data. Gillnets were installed to four localities in longitudinal gradient of reservoir in epilimnion where is the highest abundance of fish. Sampling was performed in August from 2009 to 2016. Results of this thesis show that females and males have different life histories and that bleak and roach are significantly bigger and older than males. The size dimorphism in bream was confirmed but not age difference between sexes. Sexes of bream had different diet. Males...
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The Sexual Segregation of fish from family Cyprinidae in the Řimov Reservoir
Žák, Jakub ; Prchalová, Marie (advisor) ; Čech, Martin (referee)
The sexual segregation, defined as different use of space by sexes is widespread phenomenon in the animal tree of life. As a result of segregation there is a different use of resources such as habitat, prey items or different threat by predation. Nevertheless it is not well studied in fish taxa except in marine environment. The common and widespread freshwater species such as a bream (Abramis brama), a bleak (Alburnus alburnus) and a roach (Rutilus rutilus) so far have not never been studied from the perspective of sexual segregation too. This thesis aims to examine the sexual segregation of these species and to test premises of sexual segregation such as sexual size dimorphism, age composition and differences in food. Afterwards the different space use of sexes in the Římov reservoir was tested. The gillnet sampling was used to collect data. Gillnets were installed to four localities in longitudinal gradient of reservoir in epilimnion where is the highest abundance of fish. Sampling was performed in August from 2009 to 2016. Results of this thesis show that females and males have different life histories and that bleak and roach are significantly bigger and older than males. The size dimorphism in bream was confirmed but not age difference between sexes. Sexes of bream had different diet. Males...
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Monitoring of the fish stock in Bolevecký ponds in 2016.
Jůza, Tomáš
In spring 2016, the fish stock of Bolevecký ponds in Plzeň was monitored using electrofishing boat. Strong reduction of population of unwanted species was performed during last decade for the purpose of improving of the water quality. Monitoring showed relatively low densities of unwanted fish species and relatively large amount of predatory fish in both ponds. The convenient ratio of unwanted and predatory fish species is one of the basic factor for high water quality in the future.
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Food intake of bream during the spawn period
ZEMAN, Jan
The main objective of this thesis was to assess food intake by bream, depending on the onset and end of spawning period. To meet the objectives of a practical experiment was carried out. This experiment was run on the dams Hamry and Brno in the years 2008 and 2009. Subsequently it was determined by standard methods. These methods (indirect, food frequency, filling index, index of superiority and gonadosomatic index. Subsequently, an analysis of stomach.
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Food of noncarnivor fish in newly filling dam Chabařovice
ZEMAN, Jan
Lignite mine Chabařovice is steadfast in process gradual flood, his area from year 2001 shoot up to 174 ha (2005). In incunabulum filling dam Chabařovice come to undesirable leak in cyprinids fish to dam, and that to danger development water quality. Deal with especially about these species of fish: Bream, Roach and White bream.In year 2003 come to other leak in undesirable species of fish to dam and it Rudd probably of small sedimentation tanks subleak from small dam in river basin and Ruffe from pothole Catherine. At discharge pond Zálužanský, who find over dam come to other contamination ichtyofauna dam with drain water. Of investigation ichtyofauna in June 2005 ensue from, that act especially about Roach and Rudd. Of result catching is obvious, that come to swab these fish.This fish are undesirable, because feed largely of zooplankton, who filter algae and germ and that counteract eutrophication.In essence goes about it, hold back occurrence undesirable species of fish, live on largely zooplankton and it effect predator fish were catching during ichtiologického investigation at season June and September.In laboratory were individual folders food determinantion and evaluate rake-off share individual component food.
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