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Hodnocení vývoje ichtyofauny v dlouhodobě sledovaných úsecích pstruhových revírů jižních Čech
HALÁČEK, Josef
The work provides information regarding the current development of fish populations in 30 profiles located in 16 trout fishing grounds in South Bohemia, including possible connections with the method of fishing management, temperature, and flow conditions. The work also includes recommendations regarding changes in approaches to fishery management. It is recommended to open the question of the possibility of effectively regulating fish-eating predators as soon as possible. However, these recommendations can generally be applied to similar trout fishing grounds.
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Antidepressant sertraline and fish behavior
LEXOVÁ, Veronika
Consumption of antidepressants, including sertraline, increases annually. After their intake and excretion, the residues of pharmaceuticals and their metabolites enter recipients with insufficiently treated wastewater, and they can negatively affect non-targeted organisms. This diploma thesis deals with the occurrence of antidepressant sertraline in the aquatic environment, its bioaccumulation and its effect on fish behaviour. In the experimental part of this thesis, brown trout were exposed to an environmental concentration of sertraline of 100 ng/l. Afterwards, their behaviour was observed. Results suggest that sertraline caused a change in spatial orientation expressed with left-sided laterality. Also, exploration activity was changed, which was higher in exposed fish than in the control group. It means that exposed fish were exploring the whole labyrinth. The Fulton condition factor also affected the exploratory activity of the fish. Fish in lower conditions were more likely to explore the entire tank. Concentrations of sertraline and its active metabolite norsertraline were detected in the brain and liver of fish using liquid chromatography with mass spectrometry. According to the calculation of the bioconcentration factor, it is possible to say that sertraline in trout does not reach the value of the bioconcentration factor, where substances are considered to be highly bioaccumulative. Furthermore, results suggest that the concentration of both substances in fish brains affected fish behaviour, specifically their left-sided laterality and higher exploration activity. As the concentration in the fish brain increased, the probability of these changes was higher.
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Behavioral changes in fish after methamphetamine exposure
SLIVONĚ, Miroslav
Illegal drug use has adverse consequences in the global society, but what about other organisms or ecosystem? According to the results of recently published studies, the use of illegal drugs also has a negative effect on organisms in the aquatic environment, where it enters via insufficiently treated wastewater. This diploma thesis is focused on the effect of the illegal drug methamphetamine (METH) on the change in the behaviour of brown trout (Salmo trutta morpha fario) at environmentally relevant concentrations (1000 ng/L). The results of the experiments confirmed the presence of METH and its major metabolite amphetamine (AMFA) in the liver and brain tissue of exposed fish. The changes in fish behaviour suggest that exposure to METH affected the spatial orientation of fish, expressed by left laterality, and the locomotion, represented by higher exploratory activity of exposed fish. However, the effect of METH has not been demonstrated in the presence of fish near the feed site. Based on the results of this laboratory study, the negative impact of METH and its metabolites on individuals, populations, communities, and possibly entire ecosystems was concluded.
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Diet of Eurasian otter (Lutra lutra) in relation to the stocking of brown trout (Salmo trutta m. fario) and grayling (Thymallus thymallus)
Lyach, Roman ; Čech, Martin (advisor) ; Poledník, Lukáš (referee)
This study aimed to evaluate otter predation on stocked trout and grayling. The diet composition of piscivorous Eurasian otters (Lutra lutra) was studied on the stream Chotýšanka in central Bohemia using spraint (otter faeces) analysis during one winter period (90 days). Stocking took place mostly in the second half of 2005. Around 5000 hatchery-reared brown trouts (Salmo trutta m. fario) of size about 10 cm, 600 graylings (Thymallus thymallus) of the same size and 480 rainbow trouts (Oncorhynchus mykiss) of size about 30 cm were stocked into the stream. Spraints were collected in December 2005 and January 2006. We found and identified 1531 fish in the spraints. The primary food source of otters was fish (almost 85 % of biomass). The main fish prey was small - sized, below 20 g in weight and 13 cm in length. The bulk of otter's diet consisted of less - valued species, especially the gudgeon (Gobio gobio). Other frequently consumed fish species were the European chub (Squalius cephalus), the common carp (Cyprinus carpio), the European perch (Perca fluviatilis), the brown trout and the rainbow trout. Consumption of stocked brown trout was 1,80 %, while cosumption of stocked rainbow trout was 10,90 % of biomass. Otters in this area consumed about 723 - 1446 brown trouts and 72 - 144 rainbow trouts...
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Stav rybího společenstva říčky Bobravy
Jeřábek, Jan
The bachelors’s thesis deals with state of the fish community in Bobrava River, resp. carp fishing ground Bobrava 2. Monitoring was performed at 4 sites, chosen based on the previous surveys, in period from April to December 2018. Basic physicochemical parameters of water were measured in situ and quantitative zoobenthos samples were taken. The abundance of zoobenthos was in range from 2,367 ind. m-2 to 12,895 ind. m-2. Ichthyologic investigations were realized using electrofishing in July 2018 and March 2019. The site survey results were evaluated and compared with each other. The abun-dance ranged from 156 ind. ha-1 to 2,066 ind. ha-1. The biomass ranged between 1.6 kg ha-1 and 41 kg ha-1. At two sites fish were not recorded. This may be the result of increa-sing anthropogenic influences or a consequence of constantly changing of climatic con-ditions.
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Revize hospodaření na malém pstruhovém toku
Gregr, Tomáš
This diploma thesis is focused on changes of the fish assemblages at two small trout brooks, more precisely on two fishing districts in the past 20 years. On the rivulet Frysavka (district Frysavka 1) and Bily brook (district Bily potok 1) was made an ichtyological survey by electrofishing. The survey was carried out at the same localities as did Machalík (1992) and Lusk (1991). Results of all surveys was compared and statistically evaluated. Together with ichtyological survey was sampled the zoobentos and measured the water discharge. Next part of thesis contains the evaluation of fisheries management level. At all monitoring sites of both brooks was found a decrease of fish assemblage abundance in past twenty years. The decrease of brown trout abundance at the Bily brook was 91 % and 100% decrease of grayling. The abundance of Frysavky rivulet declined of 75 % (compared with Lusk, 1991). The sampling of zoobenthos shown sufficient presence of natural food supply. Continual deterioration on hydrological conditions, lack of shelters and risk of predation were found to be the reason of severe drop in the fish assemblage abundance.
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Rybí společenstvo vybraných toků Jizerských hor
DOLEŽAL, Tomáš
Fish communities of selected streams of the Jizera Mountains The watercourses of the Jizera Mountains have the character of trout and grayling zones, with occurrence of indigenous populations of brown trout (Salmo truta morpha fario) and protected fish species. Fish communities have been disturbed in the past century by an increased degree of acidification of the environment, with the disappearance of native fish species from some localities. Subsequently, the brook trout (Salvelinus fontinalis) was introduced in these localities, and in some of them created sustainable populations capable of natural spawning. At present, in order to improve the environmental status of many localities, efforts to replace these stocks by the indigenous species of fish, brown trout and fathead minnow (Phoxinus phoxinus). The fish populations are also negatively affected by the fragmentation of watercourses and water use associated with the operation of hydropower plants. Attempts are currently being made to allow fish migration by bridging migration barriers by building of fish laddders. The aim of this work was the ichthyological research of the River Smědá. 10 localities on the river were electrofished and 14 fish species were found, of which three belong to the endangered species (Burbot (Lota lota), Bullhead (Cottus gobio), fathead minnow) and one species was non-native (brook trout) Based on a survey basic characteristics of the communities were determined (abundance, dominance, biodiversity and evenness). High species diversity (13 species) and biodiversity (H' 2.38-2.97) were found in the localities under Frýdlant. In the localities above Frýdlant was a lower species diversity (5 species) and biodiversity (H' 0-1.65), due mainly to the nature of the flow, but also influenced by insurmountable barriers, which make fish migration impossible
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Zhodnocení rybářského managementu pstruhového revíru Svitava 5
Polívka, Lukáš
The main aim of this thesis is to evaluate the biological status of species populations of agriculturally important fish species in the district Svitava 5 and the evaluation of the evidence in the district's ten-year series. Ichthyological surveys were carried out in autumn 2015, on 20th and 21st November. At various locations were determined basic physicochemical parameters of the water and found topographical data. Catches were made by using electrical units. All fish were returned gently back to the territory after finding plastic signs. In all localities have been detected 3 fish species from two families. The total abundance ranged from 899 to 3634 ks.ha-1 and the biomass from 58.7 to 250.6 kg per ha -1. Big drop in the number of caught individuals was recorded at grayling, when it reduce the number of catches from 21 ks.ha -1 to 1 ks.ha -1 in the ten-year series.
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Diet of Eurasian otter (Lutra lutra) in relation to the stocking of brown trout (Salmo trutta m. fario) and grayling (Thymallus thymallus)
Lyach, Roman ; Čech, Martin (advisor) ; Poledník, Lukáš (referee)
This study aimed to evaluate otter predation on stocked trout and grayling. The diet composition of piscivorous Eurasian otters (Lutra lutra) was studied on the stream Chotýšanka in central Bohemia using spraint (otter faeces) analysis during one winter period (90 days). Stocking took place mostly in the second half of 2005. Around 5000 hatchery-reared brown trouts (Salmo trutta m. fario) of size about 10 cm, 600 graylings (Thymallus thymallus) of the same size and 480 rainbow trouts (Oncorhynchus mykiss) of size about 30 cm were stocked into the stream. Spraints were collected in December 2005 and January 2006. We found and identified 1531 fish in the spraints. The primary food source of otters was fish (almost 85 % of biomass). The main fish prey was small - sized, below 20 g in weight and 13 cm in length. The bulk of otter's diet consisted of less - valued species, especially the gudgeon (Gobio gobio). Other frequently consumed fish species were the European chub (Squalius cephalus), the common carp (Cyprinus carpio), the European perch (Perca fluviatilis), the brown trout and the rainbow trout. Consumption of stocked brown trout was 1,80 %, while cosumption of stocked rainbow trout was 10,90 % of biomass. Otters in this area consumed about 723 - 1446 brown trouts and 72 - 144 rainbow trouts...
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Identification of the main components of food in nutrient brown trout during the growing season.
ANDONIU, Andreas
The aim of this bachelor thesis was to identify main food components of brown trout in Živný brook at two localities above and under the town of Prachatice, and describe its changes during the season. Sampling took place at five dates, when at least 10 individuals was caught from each sampling site for stomach content analysis. Modified Costello method was used to visualize feeding strategy of trout from particular sampling sites. Macrozoobenthos prevailed in food of trouts from both sampling sites, however terrestrial organisms (snails and earthworm) were also found besides adults of aquatic insect. Mayfly larvae, caddisfly larvae, adult dipterans were the most numerous represenatives of macrozoobenthos found in food of trout. In spite of that, leeches, Asselus aquaticus and chironomid larvae prevailed in site E. Differences in presence of specific benthic organisms in trout´s food were recorded due to inflow from WWTP Prachatice. In influenced locality mayfly larvae or plecopteran larvae occurred less due to organic pollution whereas leeches or Asselus aquaticus withstand higher organic pollution and thus dominated in locality E. Feeding strategy of trout was therefore aimed at above mentioned organisms, especially easily catchable and frequent in macrozoobenthos community.
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