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Past, present and future of lake trauts
Blabolil, Petr ; Peterka, Jiří ; Čech, Martin ; Draštík, Vladislav ; Frouzová, Jaroslava ; Jůza, Tomáš ; Kratochvíl, Michal ; Matěna, Josef ; Muška, Milan ; Prchalová, Marie ; Říha, Milan ; Sajdlová, Zuzana ; Šmejkal, Marek ; Tušer, Michal ; Vašek, Mojmír ; Vejřík, Lukáš ; Kubečka, Jan
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What do the fish say about the quality of aquatic ecosystems
Blabolil, Petr ; Říha, Milan ; Peterka, Jiří ; Prchalová, Marie ; Vašek, Mojmír ; Jůza, Tomáš ; Čech, Martin ; Draštík, Vladislav ; Kratochvíl, Michal ; Muška, Milan ; Tušer, Michal ; Frouzová, Jaroslava ; Ricard, Daniel ; Mrkvička, Tomáš ; Sajdlová, Zuzana ; Vejřík, Lukáš ; Šmejkal, Marek ; Borovec, Jakub ; Matěna, Josef ; Boukal, David S. ; Kubečka, Jan
The first Czech methodology for the assessment of ecological potential of heavily modified water bodies and artificial water bodies based on fish communities was developed. The first step of developing the methodology was preparing the typology of water bodies. The typology distinguishes between water bodies of different altitudes and with and without thermal stratification. Fish were sampled by multimesh gillnets following European standard procedures. The selection of fish metrics was based on statistical analyses in which metrics (fish community indicators) were correlated with the most common stressor – eutrophication. The analysis detected several sensitive metrics (metrics showing the best correlation with the stressor) in which ecological class boundaries were set. Afterwards, combination of sensitive metrics was used for calculation of the ecological quality ratio (EQR) for each of the reservoir sampled. The EQR expresses the deviation between a reservoir’s current ecological status and its maximum potential. The next step consisted of validating the EQR with an independent pressure index and verifying the time stability of ecological potential assessment. The metrics used in the methodology fulfill all the obligations set forth in the Water Framework Directive (2000/60/EC), which include assessment of the composition, abundance and age structure of fish fauna.
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Fish detection with modern sonar systems
TUŠER, Michal
This dissertation thesis was focused on improving the methodology to detect fish with modern sonar systems in lakes and reservoirs. The first part of the thesis is aimed to the vertical beaming acoustics with a key focus on the acoustic dead zone and its practical solution. The second part deals with the fish orientation in reservoir?s open waters and its consequences in horizontal beaming acoustics. The last one dedicates to the DIDSON multi-beam sonar and its reliability in detection and sizing of fish.
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Fish orientation along the longitudinal profile of the Rimov reservoir
TUŠER, Michal
The aim of this work was to verify the assumption of random fish orientation in the lacustrine zone of the ``canyon-shaped{\crqq} Rimov reservoir and to compare distributions of fish orientation in the lacustrine and tributary zone. The study confirmed that most fish were oriented randomly in the lacustrine zone of the reservoir, whereas in the tributary fish moved predominantly in parallel with the longitudinal axis of reservoir.
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How shall we study the fish stock of our large water reservoirs?
Kubečka, Jan ; Matěna, Josef ; Čech, Martin ; Draštík, Vladislav ; Frouzová, Jaroslava ; Hohausová, Eva ; Jarolím, Oldřich ; Jůza, Tomáš ; Kratochvíl, Michal ; Muška, Milan ; Peterka, Jiří ; Prchalová, Marie ; Říha, Milan ; Tušer, Michal ; Vašek, Mojmír
Quantitative fish stock assessment recently advanced significantly in the Czech Republic. Sampling of open water was facilitated by application of scientific echosounders, trawls, Nordic multimesh gillnets, purse seines and booming electoshockers. Simplified combination of the above methods was recommended for the monitoring of larger stagnant water the Water Framework Directive of EU. Combination of all above approaches with more classic ones (beach seining, benthic gillnets) is being used for „complex fish stock assessment“ providing the assessment of abundance, biomass, species and age composition of all important species in all important habitats of the reservoirs. Further improvements of results is likely to be achieved by the application of multibeam acoustic cameras and by mitigation of the problems connected with quantitative trawling of large fish
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Fish stock of the Orlík Reservoir after first years of operation of Temelín Nuclear power plant
Kubečka, Jan ; Čech, Martin ; Říha, Milan ; Jůza, Tomáš ; Frouzová, Jaroslava ; Draštík, Vladislav ; Hladík, Milan ; Kratochvíl, Michal ; Prchalová, Marie ; Tušer, Michal ; Vašek, Mojmír
The fish stock of the Orlik reservoir, Czech Republic was surveyed by shore seining and scientific echosounder (Simrad EY 500). Reservoir was dominated by cyprinids (roach, bream) with considerable share of predatory fish and perch. Inshore biomass an abundance was 302 kg/ha and 3920 inds/ha respectively. Populations show sustainable recruitment without variation of year class strength. The open water biomass estimated by hydroacoustics was 145.5 kg/ha. Assuming hydrological conditions of light flood in June 2004 it was not possible to trace any changes of the fish stock of the reservoir connected with the operation of the Temelin nuclear power station.
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Fish diversity and spatial distribution of YOY fish in Vlatava cascade reservoirs
Draštík, Vladislav ; Kubečka, Jan ; Jůza, Tomáš ; Jarolím, Oldřich ; Hladík, Milan ; Kratochvíl, Michal ; Prchalová, Marie ; Říha, Milan ; Tušer, Michal
Fish communities of YOY were studied in four cascade reservoir by beach fry-seining and fry trawling. Highest fish fry density was found in Slapy and Vrané reservoir. Lowest density was found in Kamýk and Štěchovice reservoir, two small reservoirs with shortest retention time, lowest oxygen concentration and temperature. Pelagic fish fry assemblages had much lower density than littoral assemblages and follow general fish longitudinal gradient. Littoral assemblages were more difficult to interpret due to more factors which can play important role in fish fry spatial distribution (such as bottom substrate and slope, complexity of shoreline, availability of water vegetation). Cyprinid species (bleak (.i.Alburnus alburnus./i.), roach (.i.Rutilus rutilus./i.), bream (.i.Abramis brama./i.)) prevailed in most reservoirs, only in Kamýk reservoir percid species (perch (.i.Perca fluvitilis./i.), ruffe (.i.Gymnocephalus cernua./i.)) prevailed.
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Complex assessment of the fish assemblage of the Želivka reservoir, the biggest water supply reservoir in the ČR, in years 2004 and 2005
Prchalová, Marie ; Kubečka, Jan ; Jůza, Tomáš ; Říha, Milan ; Jarolím, Oldřich ; Tušer, Michal ; Peterka, Jiří ; Vašek, Mojmír
In the summer 2004 and 2005, the complex assessment of the fish assemblage of the Želivka reservoir (1432 ha) was carried out by gillnetting, adult and fry seining, adult and fry pelagic trawls and hydroacoustic sampling. Detailed picture of the fish assemblage was composed from every fishing gear from every depth strata of the open water as well as from the littoral zone. During two-years survey, 40.168 fish of 19 species and one hybrid were captured. The fish assemblage was dominated by cyprinid species in both years – bleak prevailed in the open water together with roach and bream; perch was abundant in the littoral zone. The assemblage of the Želivka reservoir was found to be in the stable cyprinid phase. The average abundance was 1.700 ind/ha and average biomass was 110 kg/ha. In the fish spatial distribution, the general gradients could be found – higher abundance and number of species in the tributary area and in the epilimnion and littoral.
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