Age-related trends in otolith chemistry of Merluccius merluccius from the north-eastern Atlantic Ocean and the western Mediterranean Sea
B. Morales-Nin A D , S. C. Swan B , J. D. M. Gordon B , M. Palmer A , A. J. Geffen C , T. Shimmield B and T. Sawyer BA CSIC-UIB Institut Mediterrani d’Estudis Avançats, Miguel Marqués 21, 07190 Esporles, Illes Balears, Spain.
B Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, Oban, Argyll, PA37 1QA, Scotland, UK.
C Department of Biology, University of Bergen, 5020 Bergen, Norway.
D Corresponding author. Email: beatriz.morales@uib.es
Marine and Freshwater Research 56(5) 599-607 https://doi.org/10.1071/MF04151
Submitted: 13 July 2004 Accepted: 2 March 2005 Published: 21 July 2005
Abstract
Sagittal otoliths of European hake obtained from five geographic locations in the north-eastern Atlantic and western Mediterranean were examined using laser ablation and inductively coupled plasma mass spectrometry. Otolith sections were analysed for the isotopes 24Mg, 55Mn, 66Zn, 85Rb, 86Sr, 138Ba and 208Pb, measured relative to 43Ca counts. These analyses considered only age 0 (core area) and ages 1 to 3. Age-related trends in otolith elemental composition were observed in hake from all areas, but were masked by variability between locations. Elemental concentrations generally decreased outside the core, with some increase at age 3. The composition of the otolith core was very distinct from that of the other growth increments. In the Mediterranean, part of this differentiation was a result of Mn, which was present in the core at high concentrations compared with the rest of the otolith. Mediterranean otoliths also had higher concentrations of Sr, Zn and Ba in the core. For most samples a similar trend was observed, although samples from one of the Mediterranean areas showed some differences, mainly in the concentrations of Mg and Sr. These results provide new empirical evidence of the variation in elemental concentrations across hake otoliths with age, at least throughout the first 3 years of life.
Extra keywords: inductively coupled plasma mass spectrometry, laser-ablation analysis, population.
Acknowledgments
The results presented in the present paper comprise parts of a project entitled Otolith Microchemistry as a Means of Identifying Stocks of Deep-water Demersal Fish (OTOMIC) (FAIR CT98–4365), which was part-funded by the European Commission. Part of Dr J. D. M. Gordon’s contribution to the current paper was supported by a Spanish Ministry of Education Sabbatical Grant (SAB2002–0239).
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