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Distribution and diversity of fish fry in different habitats of the Slapy reservoir
Kratochvíl, M. ; Kubečka, Jan ; Matěna, Josef
The fish fry assemblages of the Slapy reservoir (Czech Republic) were studied in May and June 2002. The aim of this study was to estimate diversity and distribution of fish fry in three habitats – epipelagic (depth 0 – 4 m), bathypelagic (depth 10 – 16 m) and littoral areas. Percids were present both in epipelagic and bathypelagic areas, while cyprinids preferred living in upper layers of the water column. During the dusk, bathypelagic fish started migration towards surface layers, throughout the dawn they returned back to the deeper layers. The highest densities of fish fry were observed in epipelagic zone during nighttime. Perch was revealed as the dominant fry species in Slapy reservoir, pikeperch was also abundant in the open water. Both during day and night, perch was usually the most common species in all habitats, cyprinids were most abundant in the littoral zone in May, only.
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Ichtyofauna of the border Malše River
Matěnová, V. ; Matěna, Josef
Ichthyological investigation of the border section of the Malše River was performed in 2002 and 2003. The occurrence of brook lamprey larvae and five rheophilous fish species was confirmed – brown trout, common sculpin, grayling, burbot, stoneloach. Species escaping from fishponds – perch and common carp were found in negligible numbers. The brown trout dominated in numbers at all investigated profiles. The length and age analysis of the brown trout population showed the dominance of YOY fish, the population exhibited a harmonical age class composition. Results confirmed successful natural reproduction of trout, grayling, burbot and bullhead. The following investigation in 2003 oriented specially on the occurrence of brook lamprey proved that the population remained unaffected by the floods in 2002. The border Malše River represents an athropogenically slightly affected watercourse with suitable conditions for natural reproduction of all indigenous species found during the study.
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