Journal Article

Progress in determining southern blue whiting (<i>Micromesistius australis</i>) target strength: results of swimbladder modelling

Adam J. Dunford and Gavin J. Macaulay

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 63, issue 5, pages 952-955
Published in print January 2006 | ISSN: 1054-3139
Published online January 2006 | e-ISSN: 1095-9289 | DOI: http://dx.doi.org/10.1016/j.icesjms.2005.12.011
Progress in determining southern blue whiting (Micromesistius australis) target strength: results of swimbladder modelling

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  • Marine and Estuarine Biology

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Southern blue whiting target strength (TS) results from Kirchhoff modelling of swimbladder casts scanned using a hand-held 3D laser scanner are presented. The data are compared with the relationship between TS and fish length used for New Zealand stock-assessment surveys; TS = 21.8 log10(fork length) − 72.8, at 38 kHz. This relationship has its origins in the relationship used for blue whiting (Micromesistius poutassou) in the northern hemisphere, and is based on measurements on juvenile cod (Gadus morhua). The results indicate that the blue whiting relationship is not appropriate for southern blue whiting, and suggest a much steeper slope, with TS = 38 log10(fork length) − 97, at 38 kHz. Sensitivity analyses indicate that further investigations of swimbladder tilt-angle distribution and swimbladder volume are unlikely to provide evidence to support the use of the blue whiting relationship for southern blue whiting.

Keywords: acoustic target strength; Kirchhoff modelling; southern blue whiting; swimbladder

Journal Article.  2260 words.  Illustrated.

Subjects: Environmental Science ; Marine and Estuarine Biology

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