EVALUATING OTOLITH AGE ESTIMATES FOR HOPLOSTETHUS-ATLANTICUS BY COMPARING PATTERNS OF CHECKS, CYCLES IN MICROINCREMENT WIDTH, AND CYCLES INSTRONTIUM AND CALCIUM COMPOSITION

Analysis of proton microprobe data revealed cycles in strontium and ca lcium in the principal growth axis of the sagitta of the orange roughy Hoplostethus atlanticus (Trachichthyidae: Teleostei). Periodicities i n the strontium and calcium composition of orange roughy otoliths were not related in a constant way to underlying periodicities in the patt erns of checks in the otolith. The periodicities in microincrement wid ths were similar to periodicities of strontium variation in the otolit h. The theory of both the physical chemistry of elemental deposition i n the otolith, and the physiology of elemental concentrations in the e ndolymphatic sac support an extrinsic, annual cycle in otolith stronti um content. An extrinsic, annual cycle in otolith strontium content pr ovides a useful tool for evaluation of fish ages estimated from struct ural and chemical variation in otoliths.