VALIDATION OF AGE AND GROWTH USING MICROCONSTITUENT ANALYSIS OF FISH HARDPARTS

Abstract

Without accurate age interpretation or validation, serious errors in the management and understanding of fish populations can occur. This study employs a novel approach to age validation using trace element microconstituent analysis of hardparts. The optical zones of annuli are hypothesized to be the result of seasonal changes in organic content and experienced temperature, either of which can result in cycles of trace elements associated with annulus formation. Using Laser Ablation ICP-MS analysis, we tested for periodicity in hardpart Ca, Cu, P, Sr, Mg, Mn, Zn, and Ba in comparison to the periodicity of annulus zonation (opaque and translucent zones). Initial tests were conducted for black sea bass, a species for which yearly annulus formation has been validated. Periodicities in elemental profiles in otoliths were identified using a Lomb-Scargle periodogram analysis that confirmed that cycles in Mg corresponded to annulus formation in the model species. This same approach was applied to Atlantic monkfish, a species without a valid ageing procedure. Annular chemical oscillations occurred in illicia hardparts that exhibited modest agreement (80.7%) with known-age samples.