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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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Effect of catastrophic flooding on the composition of the fish stock of the Římov reservoir
Kubečka, Jan ; Prchalová, Marie ; Hladík, Milan ; Vašek, Mojmír ; Říha, Milan
In 2002, great flood occurred in the Římov reservoir. Fish stock of the reservoir was sampled before and after the flood by night beach seinings, pelagic and benthic gillnets, traps and electrofishing of spawning shoals of common bream. The fluctuations of most species (roach, bream and their hybrid, perch, ruffe, bleak, white bream, asp, pikeperch, eel, catfish) were random and can be attributed to interhabitat migrations rather to the effect of flooding. The share of certain species (carp, tench, goldfish, trout, dace, gudgeon) increased as they were flushed from ponds and fishing grounds in the catchment. Increased share of these species was detected in the spring 2003, while during August, the share of flooded fish decreased near to the usual level. The ‘climax’ cyprinid dominated fish stock proved itself to be very resistant to the extreme flood.
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