Did the management of the recreational fishery, water quality and flow of water modify the assemblage of fish in the lower part of the River Rokytná (Czech Republic) over the period 1968-2006?
| Autor: | Lusk, Stanislav, 1940- |
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| Další autoři: |
Pivnička, Karel, 1943-
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| Jazyk: | angličtina |
| Předmět: | |
| Druh dokumentu: | Non-fiction |
| ISSN: | 1211-376X |
| Abstrakt: | Abstract: In 39 samples of fish collected in autumn 1968-2006 in the River Rokytná using electric fishing there were a total of 26 species of fish, with the average number per sample increasing from 11 to 15. Of the nine native species eight were present in all the samples and stone loach (Barbatula barbatula Linnaeus, 1758) in 31 samples. Five species were in more than 50% of the samples and the frequency of the remaining species was between 3-29%. The abundance of fish decreased from 5000 to 3300 and biomass from 320 to 180 kg×ha-¹. The anglers caught 30 to 290 kg×ha-¹× year-¹ of carp, Cyprinus carpio (Linnaeus, 1758), over the period 1950-2006 and the catches of native nase, Chondrostoma nasus (Linnaeus, 1758), chub, Leuciscus cephalus (Linnaeus, 1758), and barbel, Barbus barbus (Linnaeus, 1758), were greatest in 1965 to 1967 with catches of 40.7, 31.8 and 8.7 kg×ha-¹, respectively, and then gradually decreased both in terms of the biomass caught by anglers and in the samples. The four significant RDA models confirmed that the environmental factors selected had an effect on the biomass of the different species in the the whole assemblage. High values of BOD and N NH₃ negatively affected dace and bitterling and high water flow positively that of barbel, chub, nase and schneider, and negatively gudgeon, dace, bitterling and stone loach. In addition nase, schneider, dace and bitterling were negatively affected by the number of carp stocked that were recorded as caught. Changes in the environment and management of recreational fishing significantly altered the number of species of fish and the abundance and biomass of the individual species in the assemblage. |
| Databáze: | Katalog Knihovny AV ČR |
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