Journal Article

Improved parameterization of the SDWBA for estimating krill target strength

Stéphane G. Conti and David A. Demer

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 63, issue 5, pages 928-935
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.2006.02.007
Improved parameterization of the SDWBA for estimating krill target strength

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Recently, a Stochastic Distorted Wave Born Approximation (SDWBA) model was proposed to improve target strength (TS) estimates for Antarctic krill, Euphausia superba. The krill shape is modelled by a collection of cylinders, and total sound scatter is estimated by semi-coherent summation of scatter from each element. The SDWBA model was evaluated with a generic krill shape comprising 14 cylinders and a phase variability of , and predictions were validated with empirical TS and total TS data at 120 kHz, and over a broad bandwidth, respectively. For general application, parameterization of the SDWBA model is improved to account explicitly for dependence among four of the model parameters: standard length of krill, number of cylinders used to describe its shape, amplitude of inter-element phase variability, and acoustic frequency. The model improvements are demonstrated, and the uncertainty in orientation distribution of krill beneath survey vessels and its ramifications on krill biomass estimates are highlighted.

Keywords: Antarctic krill; backscattering cross-section; SDWBA model; sensitivity; target strength

Journal Article.  3280 words.  Illustrated.

Subjects: Environmental Science ; Marine and Estuarine Biology

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