caa a22 4500 397550545 CHVBK 20180308164749.0 cr unu---uuuuu 161202e199604 xx s 000 0 eng 10.1006/jmsc.1996.0047 doi (NATIONALLICENCE)oxford-10.1006/jmsc.1996.0047 Reynisson Páll Marine Research Institute, PO Box 1390, 121 Reykjavík, Iceland Evaluation of threshold-induced bias in the integration of single-fish echoes [Elektronische Daten] [Páll Reynisson] In fisheries acoustics the bias introduced by a threshold in the integration of echoes from fish and other marine organisms has long been recognized. This bias is especially evident when the fish are observed in scattered concentrations. The method proposed here for evaluating the threshold-induced bias in the integration of single-fish echoes requires that the target strength distribution of the fish and the directivity pattern of the transducer be known, as well as the integration threshold in terms of the scattering cross-section of the fish. It is shown that for transducers usually employed in fisheries acoustics, the threshold effect is for all practical purposes independent of the transducer in question, thus generalizing the effect for a specific distribution. Results from direct measurements of the threshold-induced bias in the echo integration of oceanic redfish (Sebastes mentella) at 38 kHz are presented and compared with results obtained by the method proposed. The validity of the assumptions made in the numerical calculations and the effect of possible deviations from the true situation are discussed. © 1996 International Council for the Exploration of the Sea Regular Articles nationallicence acoustics nationallicence echo integration nationallicence effective equivalent beam angle nationallicence redfish nationallicence threshold nationallicence ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 345-350 1054-3139 53:2<345 1996 53 icesjms https://doi.org/10.1006/jmsc.1996.0047 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1006/jmsc.1996.0047 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Reynisson Páll Marine Research Institute, PO Box 1390, 121 Reykjavík, Iceland NATIONALLICENCE 773 0- ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 345-350 1054-3139 53:2<345 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