caa a22 4500 397551363 CHVBK 20180308164751.0 cr unu---uuuuu 161202e199604 xx s 000 0 eng 10.1006/jmsc.1996.0053 doi (NATIONALLICENCE)oxford-10.1006/jmsc.1996.0053 Improved mapping of schooling fish near the surface: comparison of abundance estimates obtained by sonar and echo integration [Elektronische Daten] [Ole Arve Misund, Asgeir Aglen, Johannes Hamre, Egil Ona, Ingolf Røttingen, Dankert Skagen, John Willy Valdemarsen] A method is described for recording fish schools near the surface by means of a computerized sonar system, a conventional echo integration unit, and sampling by a near-surface trawl. The sonar system consists of a 95 kHz SIMRAD SA950 multi-beam sonar connected to a work station with software for automatic detection and measurement of schools, and logging of the sonar data. The technique for near-surface trawling is based on re-rigging a pelagic trawl by extending the upper bridles, removing the weights, and attaching two large buoys to each wing. Pelagic fish stocks were mapped in the north-eastern Atlantic and off Namibia. The abundance estimates obtained by the near-surface recording method were compared with that obtained by conventional echo integration alone for four different surveys. It is concluded that the near-surface recording method can provide more precise mapping and abundance estimates of pelagic fish stocks in schools near the surface. © 1996 International Council for the Exploration of the Sea Regular Articles nationallicence abundance estimation nationallicence anchovy nationallicence echo integration nationallicence herring nationallicence pelagic trawl nationallicence pilchard nationallicence sonar nationallicence Misund Ole Arve Institute of Marine Research, PO Box 1870 Nordnes, N-5024 Bergen, Norway aut Aglen Asgeir Institute of Marine Research, PO Box 1870 Nordnes, N-5024 Bergen, Norway aut Hamre Johannes Institute of Marine Research, PO Box 1870 Nordnes, N-5024 Bergen, Norway aut Ona Egil Institute of Marine Research, PO Box 1870 Nordnes, N-5024 Bergen, Norway aut Røttingen Ingolf Institute of Marine Research, PO Box 1870 Nordnes, N-5024 Bergen, Norway aut Skagen Dankert Institute of Marine Research, PO Box 1870 Nordnes, N-5024 Bergen, Norway aut Valdemarsen John Willy Institute of Marine Research, PO Box 1870 Nordnes, N-5024 Bergen, Norway aut ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 383-388 1054-3139 53:2<383 1996 53 icesjms https://doi.org/10.1006/jmsc.1996.0053 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1006/jmsc.1996.0053 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Misund Ole Arve Institute of Marine Research, PO Box 1870 Nordnes, N-5024 Bergen, Norway aut NATIONALLICENCE 700 1- Aglen Asgeir Institute of Marine Research, PO Box 1870 Nordnes, N-5024 Bergen, Norway aut NATIONALLICENCE 700 1- Hamre Johannes Institute of Marine Research, PO Box 1870 Nordnes, N-5024 Bergen, Norway aut NATIONALLICENCE 700 1- Ona Egil Institute of Marine Research, PO Box 1870 Nordnes, N-5024 Bergen, Norway aut NATIONALLICENCE 700 1- Røttingen Ingolf Institute of Marine Research, PO Box 1870 Nordnes, N-5024 Bergen, Norway aut NATIONALLICENCE 700 1- Skagen Dankert Institute of Marine Research, PO Box 1870 Nordnes, N-5024 Bergen, Norway aut NATIONALLICENCE 700 1- Valdemarsen John Willy Institute of Marine Research, PO Box 1870 Nordnes, N-5024 Bergen, Norway aut NATIONALLICENCE 773 0- ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 383-388 1054-3139 53:2<383 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