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Inferring occurrence of growth checks in pike (Esox lucius) scales by using sequential isotopic analysis of otoliths

Authors


D. Gerdeaux, INRA, Station d'hydrobiologie lacustre, 75 Avenue de Corzent, BP 511, 74203 Thonon-les-Bains, France.

E-mail: gerdeaux@thonon.inra.fr

Abstract

RATIONALE

Sequential analysis of otolith oxygen isotope (δ18Ooto) values was performed by classical mechanical microdrilling and dual inlet mass spectrometry to infer the timing of growth checks in pike (Esox lucius) scales from Lake Annecy (France). It indicated that the first check on scales occurs before the first winter of life of the fish.

METHODS

Eleven fish caught in February and June 2008 were studied. Intra-individual isotopic profiles exhibit cyclic variations that are consistent with that of modeled δ18Ooto values using variations in epilimnion temperature and otolith-specific isotope fractionation equations. The positions of growth checks on scales were compared with the periodic variations of δ18Ooto values on otolith radii using an allometric relationship.

RESULTS

All individuals presented at least one check deposited before the first winter. Deposition of some checks might be linked to a shift in fish diet or habitat or to catch-and-release induced stress.

CONCLUSIONS

Although coupling between sequential analysis of δ18Ooto values and observation of scale growth features has been shown to be useful, there are limitations in the methodology, especially for the growth-attenuated region of otoliths associated with older ages. Copyright © 2012 John Wiley & Sons, Ltd.

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