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Some biological characteristics of the invasion species Perccottus glenii
Halačka, Karel ; Vetešník, Lukáš ; Koščo, J.
The occurrence of this exotic species was first observed in the Latorica River, E Slovakia, in 1998. Perccottus glenii occupied the rivers Latorica, Bodrog and Tisza together with the aquatic habitats in their floodplains. We carried out analysis of growth, haematology, fecundity, morphology of skin and gonad of individuals Amur sleeper in the locality at Svata Maria (the Bodrog River drainage area). In the locality under study the invasion of Perccottus glenii resulted in an almost total destruction of numerous populations of the native species Umbra krameri, Carassius carassius, and Leucaspius delineatus. In the past, these species were among the most numerous in that locality. Perccottus glenii has appeared to be a typical 'invasive' species that is a serious threat for native fish species showing identical habitat requirements.
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The ploidy of Carassius auratus in the Czech Republic in light of the artificial reproduction
Halačka, Karel ; Vetešník, Lukáš ; Flajšhans, M.
State of population of Carassius "gibelio" (the sex ratio and ploidy level) was for a long time observed in the Dyje river floodplain, where it has expanded by natural migration from the Danube river through Morava river in 1975-1976. Results show the time dynamics for both parameters, with increasing proportion of males and increasing proportion of diploids of both sex and the formation diploid-polyploid complex. Diploid, triploid and tetraploid males and females of silver crucian carp, Carassius auratus, as well as males of silver Blicca bjoerkna and Rutilus rutilus, were used in mating. The results show different reaction of females on used sperm even in the same group of ploidy. The existence of some groups of the individuals with a different strategy of reproduction in frame single population could be the explanation.
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The fishery management results with the wels catfish (Silurus glanis) in the selected reservoirs (fishing-grounds of the Moravian Anglers Union)
Prokeš, Miroslav ; Baruš, Vlastimil ; Peňáz, Milan
Long-term development (1951-2003) of wels catfish catches in the fishing-ground Dyje 7 (Moravian Anglers Union) was characterized. Moreover, results of wels fisheries in six dam reservoirs (Plumlov, Vranov, Brno, Letovice, Mohelno, Mušov) were also analysed. In the fishing-ground Dyje 7 the annual wels catches, during so-called riverine period (1953-1975), were 7.9 individuals (0.13 inds.hectare-1) and 31.9 kg (0.53 kg.hectare-1). The mean individual weight was 5.18 kg. During the lake period (1982-2003), the catches became significantly higher: 88 ind. (0.17 inds.hectare-1) and 1342.6 kg (2.58 kg.hectare-1). The mean individual weight was 11.62 kg. With respect to amount of catches, the start of so-called wels phase appeared roughly in the17th year of the Mušov Reservoir operation.
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Past and present of the "Angling Paradise" (fishing-ground of the Moravian Anglers Union, Dyje 7)
Baruš, Vlastimil ; Prokeš, Miroslav ; Peňáz, Milan
The comparison of fishery catches in the fishing-ground MRS Dyje 7 during the riverine (1953-1978) and lake (1981-2003) periods shows differences in species composition and quantity. Due to impoundment and fishery management (stocking), carp, bream, perch, pikeperch, asp and wels increased their production considerably. The area studied belongs presently to the most productive MRS fishing-grounds with a mean annual yield of almost 50 tones fish (95,8 kg.ha-1).
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Growth of the sterlet (Acipenser ruthenus) under conditions of Pohořelice Pond Fisheries
Baránek, V. ; Prokeš, Miroslav ; Baruš, Vlastimil ; Peňáz, Milan ; Mareš, J. ; Spurný, P. ; Němec, R.
Growth results of the sterlet (Acipenser ruthenus) reared at the Pohořelice Pond Fisheries were observed in 2003 and 2004 and subsequently analysed. During the period 28 July ů 2 September 2003 a feeding experiment (sterlet of age 1+ and 4+, 5+) was performed in which very good growth parameters were achieved: In the age category 1+ (initial mean weight of 99,5; 71,2 and 53,8 g) using DFR 1,6; 1,7; 2,1 % respectively, SWGR 1,02; 1,36; 0,91 %.d-1 , respectively and FCR 1,45; 1,10 and 2,38, respectively. In the age category 4+, 5+ (initial mean weight of 316,9; 375,0 and 478,85 g) using DFR 1,3; 1,1 and 0,9 %, respectively, SWGR 0,88; 0,73 and 0,59 %.d-1 , respectively and FCR 1,35; 1,39 and 1,42, respectively. On the basis of these results, sterlet may be considered to be an appropriate fish for intensive aquaculture and, as a native species for the Czech Republic, also for stocking into Czech running waters.
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Rearing of the zander (Sander lucioperca) stock material under controlled conditions (preliminary results)
Baránek, V. ; Mareš, J. ; Spurný, P. ; Prokeš, Miroslav ; Baruš, Vlastimil ; Němec, M.
The aim of this study was to check the possibilities of exploitation of summer zander (Sander lucioperca) fry for production of stock material under controlled conditions. Two groups of these fish were converted from natural diet to artificial diet using the semi-moist feeding mixtures (variant A) and trout feed (Dan-Ex 1352 - variant B). The average total length of imported fish was 44,3 mm and the average idividual weight was 0,606 g. There were 255 individuals in each tank. The initial stock density was 2,34 g.l-1 (3,86 ks.l-1). The water temperarute during this experiment fluctuated in intervals 21 ů 23 oC. Our simple experiment confirmed possibility of exploitation of summer zander fry to intensive rearing of stock material.
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