Journal Article

Predicting juvenile Baltic cod (<i>Gadus morhua</i>) age from body and otolith size measurements

Dariusz P. Fey and Tomasz B. Linkowski

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 63, issue 6, pages 1045-1052
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.2006.03.019
Predicting juvenile Baltic cod (Gadus morhua) age from body and otolith size measurements

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Six age-prediction models based on otolith size (weight, length, and width) and fish size (standard length, SL, and weight) were developed for juvenile Baltic cod Gadus morhua (SL, 40–153 mm; age, 90–230 d). Models were built based on stepwise selection and compared using the Akaike information criterion (AIC). Reference age was estimated by counting the growth increments in the transverse sections of sagittal otoliths (n = 310). Final comparison of the utility of the six models was based on the AIC. The best model included SL, fish weight, and sampling month as independent variables. Sampling month was added to account for differences in fish growth, after it was shown that otolith size at age was related to differences in somatic growth. The predicted age of all juveniles collected between 1991 and 1995 was used to estimate their hatch dates and growth rates. The average growth rate was 0.78 mm d−1 when estimated from predicted ages (1990–1995; n = 2036) and 0.73 mm d−1 when age based on direct increment enumeration was used (1990–1993; n = 310).

Keywords: age prediction; cod; daily increments; Gadus morhua; juveniles; otolith

Journal Article.  3807 words.  Illustrated.

Subjects: Environmental Science ; Marine and Estuarine Biology

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