Journal Article

An expanded target-strength relationship for herring

Egil Ona

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 60, issue 3, pages 493-499
Published in print January 2003 | ISSN: 1054-3139
Published online January 2003 | e-ISSN: 1095-9289 | DOI: http://dx.doi.org/10.1016/S1054-3139(03)00031-6
An expanded target-strength relationship for herring

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  • Environmental Science
  • Marine and Estuarine Biology

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Target-strength (TS) experiments on captive, adult herring have been conducted at intervals over several years to investigate the acoustic effect of pressure and seasonal changes on fish physiology. Experiments in a large, net pen (4500 m3) were done at 18, 38, and 120 kHz frequencies with calibrated, split-beam echosounders. The main ex situ results at 38 kHz, including a vertical-excursion experiment, were combined with in situ TS data collected at 38 kHz with a probing, split-beam transducer lowered into the dense herring layers, recorded during two surveys in the wintering area of the Norwegian spring-spawning stock. Multiple-linear regression analysis was used to investigate the functional relationship between TS and the measured parameters. The mean TS of herring was found to be significantly dependent on the depth (pressure) and the gonadosomatic index. These are the additional parameters included in the new TS relationship.

Keywords: acoustic surveys; herring target strength; split-beam transducer; depth-effects

Journal Article.  4043 words.  Illustrated.

Subjects: Environmental Science ; Marine and Estuarine Biology

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