Management and Ecology of river fisheries

0150326 - HBU-Z 20003033 RIV GB eng M - Část monografie knihy
Kubečka, Jan - Frouzová, Jaroslava - Vilcinskas, A. - Wolter, C. - Slavík, O.
Longitudinal hydroacoustic survey of fish in the Elbe River supplemented by direct capture.
Management and Ecology of river fisheries. Oxford: Blackwell, 2000 - (Cowx, I.), s. 14-26. ISBN 0-85238-250-2
Grant ostatní: XE(XC) International Elbe Project
Kód oboru RIV: GL - Rybářství

Fish stock of nearly 200km of the Elbe River in the Czech Republic and 15 km in Germany had been monitored by the elliptical horizontal sonar beam (Simrad EY 500, 120 kHz). New method of 'panned ultrasonic beam' had been suggested for fish sizing. Panning of the beam by 10° in front of the sonar boat enabled us to overcome the uncertainty with aspect of fish which are not swimming parallel to the current. Most fish were not recorded from their side aspect what reduced the signal-to-noise ratio slightly. The gain of the approach was that while most of fish were recorded from the predictable 80° aspect, the length of the rest was either over- or under-estimated by approximately equal amount. The biomass of fish in Elbe was surprisingly low. Average value for whole Czech section was 40 kg/ha, free flowing German Elbe had even lower values. In the Czech Elbe, it was possible to distinguish the upper parts with relatively high fish biomass and impoverished lower reaches where human impacts cumulate.
Trvalý link: http://hdl.handle.net/11104/0047864