Hidrológiai Közlöny 2008 (88. évfolyam)

6. szám - IL. Hidrobiológus Napok: „A Balaton és vízrendszere – a Balaton-kutatás története” és „A Duna-kutatás története” Tihany, 2007. október 3–5.

54 HIDROLÓGIAI KÖZLÖNY 2008. 88. ÉVF. 6. SZ. Köszönetnyilvánítás Köszönetünket fejezzük ki Dobos Gézának és Sevcsik Andrásnak a halászatok során nyújtott segítségükért. Irodalom EN 14011:2003. Water quality - Sampling of fish with electricity. European committee for standardization, Brussels, 18 p. EN 14757:2005. Water quality - Sampling of fish with multi-mesh gillnets. European committee for standardization, Brussels, 27 p. Growns, I.O., Pollard, D.A., Harris, J.H., 1996. A comparison of electric fishing and gillnetting to examine the effects of anthropogenic disturbance on riverine fish communities. Fish. Man. Ecol.3, 13-24. Murphy, B.R., Willis, D.W., (Eds.) 1996. Fisheries techniques, second edition. American Fisheries Society, Bethesda, Maryland. Olin, M., Malinen, T., 2003. Comparison of gillnet and trawl in diurnal fish community sampling. Hydrobiologia 506-509, 443-449. Specziár., A., Tölg, L., Bíró, P., 1997. The fish stock structure in the reed stands of Lake Balaton. Állattan. Közi. 82, 109-116. (in Hungarian with a summary in English) Fish assemblages in reed habitats of Lake Balaton - a comparison between gillnet sampling and electric fishing Erős, T. - Specziár, A. - Bíró, P. Balaton Limnological Research Institute of the Hungarian Academy of Sciences Abstract: In this study species number, assemblage composition (relative abundance and biomass data), length class distributions and some additional ecological metrics of fishes were compared between two data sets collected simultaneously using gillnet sampling and electric fishing in the reed habitats of a large shallow lake. Electric fishing proved to be more effective in detecting new species. Ordinations based on relative abundance and biomass data indicated highly contrasting differences between the two methods. Gillnet caught bleak in much higher relative abundance but its shape and size selectivity also reinforced differences between the two methods. Data on fish size distribution supported these findings and showed that gillnet caught relatively more middle sized fish while electric fishing resulted relatively more small and large fish. Estimates of gillnetting and electric fishing differed both in the number and proportion (rel. abundance and biomass) of non-native species and differences were found in the proportions of various guild components (feeding, spawning, habitat). However, based on our data it can not be concluded which gear's estimate is closer to reality. Our study illustrates that reliance on single-gear surveys can be misleading in assessing fish assemblages in the reed habitats of a shallow, eutrophic lake. Keywords: sampling methods, fishes, Lake Balaton Klossy Irén alkotása