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Biomorphometry and growth rate of the sterlet (Acipenser ruthenus) in the Czech Republic
Prokeš, Miroslav ; Baruš, Vlastimil ; Peňáz, Milan ; Baránek, V. ; Ošanec, J. ; Šutovský, I.
Two samples of 40 and 30 juvenile specimens of the sterlet (Acipenser ruthenus Linnaeus, 1758) reared in special aquacultural facilities in the Czech Republic (and originating from Russia), and in the Slovak Republic (originating in the Danube Slovak section) were biometrically analysed and compared. Specimens did not differ in the maximum-minimum range of their meristic characters from the description presented for sterlet, but differ significantly in mean values in 4 (of 6) meristic and 14 (of 27) metric characters compared. On the basis of UPGMA it was found that the sample of sterlet from the CR, clusters well with other samples of the sterlet population. On the basis of PCA affinities of sterlet samples with hybrid samples of bester (A. ruthenus x Huso huso) were found. In comparative rearing of juvenile sterlet and Siberian sturgeon (Acipenser baerii) under identical experimental condition intensive growth rates in the Siberian sturgeon were found.
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Abundance of the barbel, Barbus barbus in the river Jihlava
Peňáz, Milan ; Pivnička, K. ; Prokeš, Miroslav ; Baruš, Vlastimil
A four-year experiment with a total of 993 individually tagged barbel, Barbus barbus, resulted in the assessment of survival and abundance. The Jolly-Seber method was used to estimate abundance from autumn 1999 to spring 2001 (minimum 233, maximum 563 ind./ha). The mean annual survival rate was 0.862, but the partial values assessed separately for seasons (spring - autumn and autumn - spring) differed considerably and the possible reasons for this phenomenon are discussed. On the basis of known survival rate, the abundance was subsequently estimated (for the entire studied stretch and per hectare) using the Petersen capture-recapture method for the period spring 1999 to autumn 2001. Its mean values reached 303 +- 110 ind./ha (minimum 195, maximum 498 ind./ha). These results were in autumn 2001 supported by another simultaneously conducted census following the removal method by Zippin (316 ind./ha).
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Community ecology of parasites of chub fry (Leuciscus cephalus L.)
Dávidová, M. ; Jurajda, Pavel ; Gelnar, M.
The formation and development of metazoan parasite community of chub fry (Leuciscus cephalus L.) was followed in the period from July 2000 to May 2001. Chub fry (N=190) were sampled monthly from the River Morava. Altogether 27 parasite species have been recorded. The most common parasites in the investigated locality were representatives of the class Monogenea, especially viviparous gyrodactylids. First, juvenile fish 29 mm in size were found to be infected with ectoparasites and metacercariae. On the opposite, host fish larger then 50 mm were colonised with intestinal parasites.
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The effect of posthodiplostomosis on the cyprinid fish fry
Ondračková, Markéta ; Dyková, Iva ; Gelnar, M. ; Jurajda, Pavel
Posthodiplostomosis, called also black-spot disease, is caused by metacercariae of Posthodiplostomum cuticola (Trematoda, Diplostomatidae). These parasites were studied on the cyprinid fish in floodplain area of the River Dyje in South Moravia. Twelve species from 16 totally explored Cyprinids were infected by metacercariae of P. cuticola during 1998, 1999 and 2001. Roach (Rutilus rutilus), rudd (S. erythrophthalmus), silver bream (B. bjoerkna), common bream (A. brama), bitterling (R. sericeus) and Prussian carp (C. auratus gibelio) were infected in all followed seasons. These species were histologicaly examined. During the cyst development the progressive maturation of connective tissue in outer layer of the cyst and infiltration of pigment cells were observed. Production of black pigment around the parasite cyst was chacteristic host reaction. Mainly melanocytes and in a small measure iridocytes took part in the pigmentation. The metacercariae of P. cuticola caused in the juvenile fish spine and body deformation. By high invasion the tissue dystrophy was observed.
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Species determination of coregonid stocks
Prokeš, Miroslav ; Baruš, Vlastimil ; Peňáz, Milan ; Kubišta, O. ; Melichar, M. ; Špinar, M.
On the basis of results in reproduction biology, early ontogenesis and morphometrics of Coregonus maraena, C. peled and their reciprocal hybrids, the characterization of artificial reproduction development and morphometrical parameter changes in the parental species due to artificial hybridization is represented here from 1970 up to the present. On the example of populations of both aquacultured coregonid species, reared in the region of the Českomoravská vrchovina Highland, the determinative characterization of eggs, eleuterembryos and juvenile specimens are presented. To be the most important determinative characters, considered are: egg size, number of myotomes, size of hatching embryos, number of gill rackers, mouth position, body depth, number of rays and anal fin size. The actual population of C. maraena does not differ morphometrically from its state before 1970, the population of C. peled differs morphometrically from the state after introduction in 1970.
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Investigation of a natural focus of tularemia in southern Moravia (Czech Republic)
Treml, F. ; Hubálek, Zdeněk ; Halouzka, Jiří ; Pikula, J. ; Juřicová, Zina ; Janík, V.
In the years 1971-1993, up to about 1% of European hares (Lepus europaeus) had antibodies against Francisella tularensis in the district of Břeclav. However, the incidence of tularemia in hares increased significantly in 1994, when nearly 6% of individuals were seropositive. In 1995-2001, a total of 479 small mammals were captured and examined for tularemia: F. tularensis was isolated from two field voles (Microtus arvalis), in 1997 and 2001. During the same period, 3030 Dermacentor reticulatus, 626 Ixodes ricinus and 60 Haemaphysalis concinna ticks, as well as 9092 Aedes spp. mosquitoes were examined. F. tularensis was only recovered from D. reticulatus (32 isolates) and I. ricinus (1 isolate).
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