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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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Density dependent growth of brown trout Salmo trutta in oligotrophic streams
Závorka, Libor ; Slavík, Ondřej (advisor) ; Frouzová, Jaroslava (referee)
This thesis deals with the influence of population density on the growth of brown trout Salmo trutta. The research was carried out in the Šumava National Park in the river basins of two oligotrophic streams, the Vydra and the Křemelná. Data has been collected between years 2005 and 2010, every spring and autumn. Fish were caught via electrofishing and the length and weight of each individual were measured. Every individual caught was marked in a unique way. A few samples of scales were taken from some of them. The scales were fixed into laboratory slides, scanned and measured by graphic software. According to the differences between annual lamellas density, the age and the annual growth of individual's body length were estimated. Thanks to these results a negative relationship between the individuals' of age 1+ growth rate and the population density was confirmed. The importance of this thesis is mainly in comparing the influence of different spatial and time definitions of population on this relationship. The influence of the population density in spring (the initial time of the growth period) was proved to be essential for the growth rate. This fact suggests the importance of compensation growth intensity after the long period of winter for individual's general growth under conditions provided by...
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Zhodnocení rybářského managementu pstruhového revíru Svitava 4
Mareš, Lukáš
Presented master thesis deals with the issue of assessment of management in salmonid fishing ground Svitava 4. The main aim was to compare the state of fish community with the state after the last survey from 2003-2004 and to evaluate the economic evidence (level of fishermen's pressure, level of reached catch and the stocking of economically important species) for ten years in a row. The ichthyological survey was carried out in summer season in 2014 at four localities within the fishing ground Svitava 4. The topographic data of particular localities were measured by the modern devices. Also basic physicochemical parameters of water were measured. The catching was realized by electric-fishing gear. After measuring of morphometric characteristics all the fish were returned back to the fishing ground. The survey established the presence of 8 fish species in 5 families. The abundance of fish community varied on particular localities in the range from 338 to 1633 pcs.ha-1, the biomass from 53,6 to 199,2 kg.ha-1. The fish community of concerned stream has gone through significant changes since the last survey. Considerable decrease in abundance was recorded mainly in the grayling population.
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Zhodnocení rybářského managementu pstruhového revíru Svitava 2
Bromek, Petr
The main aim of the diploma thesis is to evaluate the fish management of a trout reserve Svitava 2 and to suggest a correction on the basis of results from the performed surveys and information from the Moravian Fisherman's associotion evidence. Field surveys were realized on 3rd and 4th September 2013. During these surveys 12 fish species out of 5 families were demonstrated by electrofishing. Caught fis were released back to the river measuring weight and lenght. The ichthyologic research was evaulated using indi-cators for fish populations. On account of acquired knowledge and data, I recommend following correction: advance quantity biennial brown trout on 200 fish per hectare, reduce rainbow trout 40 fish per hectare and advence quantity biennial qrayling on 200 fish per hectare.
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The growth of brown trout (Salmo trutta, L.) in Blanice river and its tributaries
BALCAR, Jakub
The aim of the study was to compare the growth of brown trout in the river Blanice and its tributaries - Živný brook during the growing season 2013. Due to unfavorable hydrological situation in the Blanice river was used data about the growth of brown trout in a defined section of the river, obtained during an experiment in 2007.Tagged fish were divided into three size categories: small juvenile, large juvenile and adult fish.The specific growth rate of all groups of fish from the Živný brook was higher than in the same groups of fish in Blanice river. Significantly higher growth rate of small juvenile fish compared to the groups larger fish was also demonstrated in the Živný brook. The results show that the growth rate of brown trout mainly depends on the nutrient (food) content of the flow, rather than its size or population density of brown trout.
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