Ben Frey – U. Maryland Center for Environmental Science
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 otoliths. 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 electron microprobe and Laser Ablation ICPMS analyses, we tested for periodicity in otolith Ca, Cu, P, Sr, Mg, Mn and Zn and the synchrony of periodicity with 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 were identified using a Lomb-Scargle periodogram analysis that allowed for unequally spaced measurements. Periodic components were tested for significance using Fourier series harmonic filtering. Component periods and intensities were compared between each elemental series. Candidate elements identified through this analysis of black sea bass otoliths will be useful for planned applications on Atlantic monkfish, for which no validated ageing procedure exists.