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Fish assemblage of the polluted middle part of Elbe River
Švanyga, J. ; Valová, Zdenka ; Janáč, Michal ; Bialek, M. ; Machala, M. ; Jurajda, Pavel
In July 2005, four stretches of the River Elbe were surveyed. In each river stretch, 3 sections were sampled: under the weir, middle zone and above the weir. Adult fish were sampled by boat electrofishing, juvenile fish by seine netting and electrofishing . Totally, 22 species of adult fish were caught. Bleak, chub and roach were the most abundant adult species. Species richness was similar in all river stretches. Fish abundance decreased slightly downstream, both between and within river stretches. 14 species of juvenile fish were caught, most of them represented by a few individuals. Bleak and bitterling were the most common juvenile species. Chub and common bream were co-dominant species in some sections. Fish assemblage of the surveyed sections was relatively poor with a negligible natural reproduction . Despite of the strong pollution source, geomorphological and hydrological stream character seems to be the most important for fish assemblage.
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Exploatation characteristic of barbel, nase, chub and ide in the riverine and lake ecosystems
Prokeš, Miroslav ; Baruš, Vlastimil ; Peňáz, Milan
The exploatation characteristics of four potamodromous fish species, barbel (Barbus barbus), nase (Chondrostoma nasus), chub (Leuciscus cephalus) and ide (L. idus) obtained in the riverine and so-called lacustrine (man-made lake) ecosystem, exemplified on the fishing ground Dyje 7 on the river Dyje, is documented. Based on the analyse of many-year catch data of mentioned fish species, the influence of stream fragmentation was revealed upon the abundance reduction of natural populations of rheophilic fish species of concerning Dyje river sectin (located at the Mušov reservoir), as well as a necessity of strengthening these populations in the adjacent stream sections, especially by stocking of artificially produced fry, and in near future also by the construction of the new functional fish ladders.
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Using of biocide Diazinon 60 EC in fish farming and its toxicity for fish and another water organisms
Máchová, J. ; Prokeš, Miroslav ; Faina, R. ; Kroupová, H. ; Svobodová, Z. ; Peňáz, Milan ; Baruš, Vlastimil
Diazinon 60 EC (chemical insecticide, organophosphate, active substance diazinon at a concentration of 600 g/l) is used in fish-farming in well-founded cases as a biocide to supress excessive propagation of coarse daphnian zooplankton (used concentration of Diazinon 60 EC 0,010 mg/l). Diazinon 60 EC is highly toxic for daphnian zooplankton (48hEC50 = 0,00029 mg/l by the using of artificially prepared adulterating water according to the standard and 48hEC50 = 0,0029 mg/l by the using of pond water). Toxicity of Diazinon 60 EC is markedly lower for other water organisms (96hLC50 for Poecilia reticulata, Cyprinus carpio and Orcorhynchus mykiss are in the range 3-10 mg/l and 72hIC50 for Desmodesmus subspicatus = 10 mg/l). At the concentration of 0,01 mg/l (i.e. 100 g per 1 ha at 1 m mean depth of the pond), Diazinon 60 EC can highly selectively eliminate daphnian zooplankton, causes no harm to fish and is reltively quickly decomposed in the aquatic environment.
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Seasonal variability of fish samples
Konečná, G. ; Janáč, Michal ; Jurajda, Pavel
We investigated seasonal variability of fish samples on small submontane stream. Study took place on Vlára stream in Bohuslavice town. One identical 100 m long section was sampled monthly from April to November 2005. Sampling was carried out using electrofishing. Totally, 8238 individuals belonging to 18 species were caught. Number of species was constant during the year (mean +/- SE, 10.5 +/- 0.38). Nine most common species were caught each month. On the other hand, in most cases the rest of species was found just once. Gudgeon (Gobio gobio), roach (Rutilus rutilus) and chub (Leuciscus cephalus) were dominant species. Rare species probably came from lentic waters in the river basin and did not make stable populations in the river.
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Efficiencies of two types of seine net for 0+ fish sampling
Janáč, Michal ; Jurajda, Pavel
Young of the year (YOY) fish assemblages are used as indicators of a river ecological state. Though, some aspects of YOY fish sampling methodics are still not definitely solved. Present study compared YOY sampling efficiency of 5 m beach seine net and 10 m beach seine net. Study took place in a regulated upstream weir stretch of Morava River near the Lanžhot town (83. r. km) in September 2002. Ten localities were sampled by both types of net. Simultaneously, comparative electrofishing survey was conducted in the same river stretch.
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Individual growth and weight condition of the common carp (Cyprinus carpio m. domestica) in the Nové Mlýny Reservoir (preliminary results)
Habán, V. ; Prokeš, Miroslav ; Baruš, Vlastimil ; Mareš, J.
Individual tagging of the carp (C. carpio f. domestica) 2-year stockfish (K2) was initiated in 2001. In total, 10 thousands specimens were so far tagged with the anchor plastic tags and released into the Nové Mlýny Reservoir on the River Dyje in 2001-2005. According to the 36 registered recaptures (in 2004), the carp reached in the third year of life after 11-12 months exposition in the reservoir (D 316-317, mean 345.3), a body mass of 1500-3900 g (mean = 2264.4+-802.6 g) and a total length of 420-530 mm (mean = 464+-33 mm). These values reveal high trophic sources existing in the Nové Mlýny Reservoir being filled in 1988. When compared with similar data from fishponds of the Czech and Slovak Republics, the growth rate observed showed to be similar or even higher.
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Growth comparison of the (1+) juvenile sterlet (Acipenser ruthenus) by using experimental and commercial diet
Baránek, V. ; Prokeš, Miroslav ; Baruš, Vlastimil ; Peňáz, Milan ; Cileček, M. ; Mareš, J. ; Jirásek, J. ; Spurný, P.
The aim of this experiment was to check the growth rate of the (1+) juvenile sterlet. The experiment was proceeded during the 42-days period (25 July - 4 September 2005) in the hatchery of the Pohořelice Pond Fisheries. The fish were kept in four flow through tanks. In total, 45 individuals were stocked in each tank. Fish were fed by experimental (44/12) and commercial diet (Pro Aqua Brutfutter 57/15, Skretting) in two repetitions. Our experiment confirmed very good growth ability of the juvenile sterlet, together with low FCR parameter. Sterlet may be considered as an appropriate fish for intensive aquaculture and also, as a native species of the Czech Republic for stocking into Czech running waters.
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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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