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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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The occurrence of brook lamprey [Lampetra planeri (BLOCH, 1784)] in Novohradské Mountains (South Bohemia, Czech Republic)
Matěnová, V. ; Matěna, Josef
The occurrence of brook lamprey was studied in Novohradské Mountains during 1999-2003. Altogether 83 profiles on 22 second to fourth order brooks and streams were fished by means of electroshockers. The area investigated can be divided into three basins. Significant differences were found between basins with respect to frequency of occurrence and density of lamprey populations. The highest frequency of occurrence was in the Stropnice River basin (6 streams of 8 investigated, average abundance 2598 inds ha-1), followed by the Malše River (4 streams of 8 investigated, average abundance 844 inds ha-1). In the Černá Rivulet basin only in 1 of 6 streams investigated the brook lamprey was found at very low densities - 28 inds ha-1 on average. The lamprey contributed substantially to the whole forming more than 50
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