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Seasonal dynamics of ergasilosis in reservoir fish
Jelínková, E. ; Krechler, I. ; Jurajda, Pavel ; Papežíková, I. ; Navrátil, S. ; Marková, Z. ; Kosour, D. ; Palíková, M.
We evaluated ergasilosis seasonal dynamics at two reservoirs (Hubenov, Korycany) in the Morava River Basin (Czech Republic). Samples of fish were obtained at monthly intervals between April and October 2014. In total, 189 fish of 11 species were caught using electrofishing and seine nets. Highest overall values for E. sieboldi infection intensity and abundance were recorded at Hubenov in June and September. Prevalence ranged between 80 and 100%. Two highest peaks of infection intensity and abundance were recorded at Korycany in May and the second around September and October, prevalence ranging between 33 and 100%. As the nauplius and copepod stages of arthropods form part of the zooplankton assemblage, they will be found at highest numbers in reservoirs with low predatory pressure, i.e. where predatory fish suppress zooplanktonophagic fish species.
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Hodnocení rybářského využití koupacích vod v povodí řeky Moravy s ohledem na možné interakce s vývojem kvality vody
Adámek, Zdeněk ; Jurajda, Pavel
The evaluation of possible relationship between fisheries management and water quality in bathing sites in the Morava River catchment area, as presented on public web pages www.koupacivody. cz, was performed on an example of 24 evaluated waterbodies. On the sites, which belong to the angling grounds, an obvious relationship between the proportion of predatory fish biomass in fish yields (F/C index) and bathing quality of appropriate sites was recorded. Mean F/C values in fish catches, as the most appropriate criterion, amounted to 17.8 and 21.5 in bathing suitable water and bathing suitable water with deteriorated sensory properties, \nrespectively. It seems apparent that the bathing water quality reflects in certain extent the principal characteristics of fisheries management. In carp farming ponds, incorporated legally among bathing sites, this tendency was not so obvious and it seems that not even the intensity of supplementary feeding was the main reason limiting the suitability for bathing.
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Ichthyological survey and evaluation of biomanipulation measures at Hamry reservoir in 2015
Jurajda, Pavel ; Adámek, Zdeněk ; Janáč, Michal ; Jurajdová, Zdenka ; Mikl, Libor ; Šlapanský, Luděk ; Roche, Kevin Francis ; Kopeček, Lukáš
This study, which has been running since 2008, examines the use of the Hamry Water Reservoir as a model for fish community biomanipulation studies with the aim of improving water quality. Of primary interest to the Reservoir administrators, the Elbe River Basin authority s.p., is the maintenance of high water quality for drinking purposes, thereby preventing conflict of interest with multiple stakeholders. In addition, the study aims to determine whether biomanipulation of fish communities can be undertaken effectively in a reservoir.
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Pilot study on the efficient use of ponds greater than 100 hectares
Mrkvová, Markéta ; Jurajda, Pavel ; Adámek, Zdeněk ; Zukal, Jan
Fish distribution in carp ponds tends to be uneven as fish prefer those parts nearer the feeding sites. As such, carp usually only occupy around two thirds of the pond area. Compared with more remote parts of the pond, control sampling campaigns showed the regular occurrence of significantly larger fish at the feeding sites. Further, fish located on the feeding sites consumed cereals almost exclusively, whilst those outside the feeding sites grazed predominantly on zooplankton. Environmental parameters at the feeding sites differed from those in the surrounding area, particularly in relation to the post-feeding period. We recommend that fish farmers both increase the size of feeding sites and alternate feeding at different sites in an effort to spread the fish stock over the whole pond area, thereby better utilising natural food resources.
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Ichthyological monitoring of the Hamry water reservoir in the year 2014
Jurajda, Pavel
This study, which has been running since 2008, examines the use of the Hamry Water Reservoir as a model for fish community biomanipulation studies with the aim of improving water quality. Of primary interest to the Reservoir administrators, the Elbe River Basin authority s.p., is the maintenance of high water quality for drinking purposes, thereby preventing conflict of interest with multiple stakeholders. In addition, the study aims to determine whether biomanipulation of fish communities can be undertaken effectively in a reservoir.
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The structure of zooplankton in diet of common bream (Abramis brama) during biomanipulation
Zapletal, T. ; Špaček, J. ; Jurajda, Pavel ; Všetičková, Lucie
The structure of zooplankton in diet of common bream (Abramis brama) was analysed in the Hamry water supply reservoir during the period 2011-2014. Fish were captured by gill netting, beach seining and electrofishing in the littoral part of reservoir. Minimum twenty specimens of each size group were taken for analysis on each sampling occasion. Zooplankton in the diet of adult bream SL 210-315 mm and subadult SL 124-186 mm made recedent proportion. Juvenile bream (0+) SL 18-51 mm consumed zooplankton only. Daphnia galeata was dominant there. We found that decrease of cladoceran communities in the water supply reservoir might to cohere (related) with this specific feeding activity of bream's fry and the feeding competition of bream's and perch's fry in it's habitats.
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