caa a22 4500 397551673 CHVBK 20180308164752.0 cr unu---uuuuu 161202e199604 xx s 000 0 eng 10.1006/jmsc.1996.0027 doi (NATIONALLICENCE)oxford-10.1006/jmsc.1996.0027 Interpretation of in situ target-strength data [Elektronische Daten] [D. N. MacLennan, A. Menz] Target strength (TS) may be estimated as a function of fish length (L) by comparing in situ acoustic measurements with the fish size distribution from trawl catches. The acoustic and fishing data are directly comparable only if they are samples from the same population, but the TS measurements depend on the detection of isolated targets which may not be representative of the ensonified population. Errors may occur through the false detection of multiple targets, and the size-dependence of schooling density means that larger fish are more likely to be detected. We show that such effects can result in the estimated TS being biased high. We describe a stochastic method for estimating the constant b in the formula TS=20 Log (L)−b, by a least-squares fitting procedure. It is assumed that the echo-amplitude has a Rayleigh distribution. The method has been applied to data from surveys of cichlids in Lake Malawi. From 33 independent measurements of Diplotaxodonspp. around 15 cm in length, b is 67.4±0.2 dB. © 1996 International Council for the Exploration of the Sea Regular Articles nationallicence cichlids nationallicence Diplotaxodon nationallicence Lake Malawi nationallicence target strength nationallicence MacLennan D. N. SOAFD Marine Laboratory PO Box 101, Victoria Road, Aberdeen, AB9 8DB, Scotland aut Menz A. Natural Resources Institute Central Avenue, Chatham Maritime, Kent, ME4 4TB, England aut ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 233-236 1054-3139 53:2<233 1996 53 icesjms https://doi.org/10.1006/jmsc.1996.0027 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1006/jmsc.1996.0027 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- MacLennan D. N. SOAFD Marine Laboratory PO Box 101, Victoria Road, Aberdeen, AB9 8DB, Scotland aut NATIONALLICENCE 700 1- Menz A. Natural Resources Institute Central Avenue, Chatham Maritime, Kent, ME4 4TB, England aut NATIONALLICENCE 773 0- ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 233-236 1054-3139 53:2<233 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