caa a22 4500 397551002 CHVBK 20180308164750.0 cr unu---uuuuu 161202e199604 xx s 000 0 eng 10.1006/jmsc.1996.0017 doi (NATIONALLICENCE)oxford-10.1006/jmsc.1996.0017 Patchiness of longitudinal fish distributions in a river as revealed by a continuous hydroacoustic survey [Elektronische Daten] [Annie Duncan, Jan Kubecka] During July and September 1993, the longitudinal distributions of fish communities in five reaches of the River Thames were obtained by mobile acoustic surveys at night, using a BioSonics dual-beam echosounder (420 kHz) with a transducer beaming horizontally across the river. Although acoustic ranges were small (10-20 m), the total sampled volume was large. Continuous records of absolute fish densities in the water column were obtained by echo integration at 20 m or 40 m intervals along the river. The striking feature of the acoustic data is the evidence they offer for different scales of patchiness in continuous longitudinal distributions of fish targets. The scale of patches varied in density and size. Some obvious larger patches could be associated with river features (sewage outfalls) or particular events (mass emergence of insects at dawn). For other larger patches, there were no obvious causes but they were persistent in replicated runs during one night or occupied the same locality in both months. Patchiness at smaller scales was also detectable all along the river course between the larger patches. © 1996 International Council for the Exploration of the Sea Regular Articles nationallicence fish density nationallicence hydroacoustics nationallicence longitudinal distribution nationallicence patchiness nationallicence river nationallicence Duncan Annie Hydroacoustic Unit RHIER, Royal Holloway University of London, Egham, Surrey, TW20 0EX, England. aut Kubecka Jan Hydrobiological Institute Czech Academy of Sciences, Na Sadkach 7, 370 05 Ceske Budejovice, Czech Republic aut ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 161-165 1054-3139 53:2<161 1996 53 icesjms https://doi.org/10.1006/jmsc.1996.0017 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1006/jmsc.1996.0017 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Duncan Annie Hydroacoustic Unit RHIER, Royal Holloway University of London, Egham, Surrey, TW20 0EX, England aut NATIONALLICENCE 700 1- Kubecka Jan Hydrobiological Institute Czech Academy of Sciences, Na Sadkach 7, 370 05 Ceske Budejovice, Czech Republic aut NATIONALLICENCE 773 0- ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 161-165 1054-3139 53:2<161 1996 53 icesjms Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford