Verification of first annulus formation in the illicia and otoliths of white anglerfish, Lophius piscatorius using otolith microstructure

Abstract

Microincrements in the lapilli otoliths of Lophius piscatorius L. were used to validate the age of fish <27 cm TL collected in spring and autumn. Contrary to published estimates of size at age based on illicia by Dupouy et al. (1986) and Duarte et al. (1997), these small specimens were found to be either 0- or 1-group. Comparison between the macrostructures of illicia and sagittae indicated that a translucent zone is formed in the illicia of most 0-group by autumn but not in sagittae. Hence, earlier estimates of small size at age may have arisen from incorrect interpretation of the time of first translucent zone formation in illicia. In addition to enabling age validation, microstructure provided a means of distinguishing between the translucent material that forms false rings and annuli. Annuli appeared as a sequence of gradually declining increment widths whereas false rings were characterized by an abrupt check in otolith formation followed by increments similar in width to adjacent opaque material. The implications of these findings to age reading and interpretation are discussed. 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd.