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HYGIENIC QUALITY OF FISH FROM SIGNIFICANT FISHING WATERS BEROUNKA 1, LUŽNICE 6, OTAVA 4, OTAVA 7 (P)
BARTOŇ, Jiří
The main aim of this study was to evaluate hygienic quality of fish from significant fishing waters: Berounka 1, Lužnice 6, Otava 4, Otava 7 (P). Sampling was performed in 2010 by electrofishing and fishing rods. 173 individuals belonging to 13 different fish species were fished. The samples of fish muscle were analysed for the following substances: Hg, Pb, Cd, PCB, DDT and its metabolites (DDE and DDD), a-HCH, b-HCH, y-HCH, HCB. Samples of bream (Abramis brama) muscle were collected at all monitored sites (exception was Otava 7) and bream was used as reference species to compare the contamination among monitored rivers. The results were compared with valid hygienic limits. The values of contamination were in most cases very low and far below the limits. Only mercury was identified as a risk contaminant in all monitored rivers. Average concentrations of mercury in the muscle of bream were in the range of 0.261-0.284 mg/kg and were comparable in all rivers. The hygienic limit for mercury (0,5 mg/kg) was exceeded only in 4 cases - one individual sample of bream from Otava, two mixed samples of asp (Aspius aspius) from Berounka and Lužnice, one mixed sample of perch (Perca fluviatilis) drom Otava. The highest value of total mercury content (0.768 mg/kg) was found in asp from Lužnice 6. All concentrations of persistent organochlorinated pollutants in fish muscle were far below the valid hygienic limits. The only health risk was posed by increased content of mercury.
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The influence of the water quality on managed ichthyocenosis in the Berounka River, 1975-2003
Pivnička, K. ; Humpl, Martin
In 1962-2004 the stepwise increase of the concentration of NO3-, NH4+, Cl-, and SO42- was found up to the end of 1980´s with their subsequent decrease; only for BOD the gradual decrease in all sites and years was observed. These environmental factors (EF) together with the fishery statistics from two fishing wards (B7 and B8) in the Berounka River near Radnice were used in RDA models for the evaluation of the variability in fish assemblage structure in relation to the given EF. The best results in both wards were obtained using model with three EF (BOD, NO3-, SO42-), next models with four (five) factors explained more variability, some EF were, however, not significant. The partial effect of carp as EF on the yield of other species was non significant in B7 and closely above the significance (p=0.036) in B8. The changes in the frequency of fish species in fishery statistics are influenced by EF; the fishery statistics can be used for the evaluation of changes in fish assemblages in the past.
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