Phase Differences between Check Ring Locations in the Orange Roughy Otolith (Hoplostethus atlanticus)

Abstract

Orange roughy (Hoplostethus atlanticus) otoliths were shown to have two different mineral phases of aragonite in the upper (anti-sulcul) and lower (sulcul) parts of medio-lateral sections of otoliths. The difference in mineral phase was characterised by differences in the direction of crystal growth, crystal size and crystal jointing. The effect of the difference in mineral phase was to change the patterns of homologous check rings observed in both the upper (anti-sulcul) and lower (sulcul) parts of the otolith. On average, about 24% of the information contained in check ring pattern of the upper (anti-sulcul) part of the otolith was retained in the lower (sulcul) part of the otolith. The loss of information may explain the difficulty in reconciling age interpretations made from sulcul check rings with age interpretations made from ultrastructural patterns in the anti-sulcul parts of medio-lateral sections of otoliths.