Age, growth and utility of otolith morphometrics as a predictor of age in the wrasse <i>Coris julis</i> (Labridae) from the eastern Adriatic Sea

Abstract

Age and growth of Coris julis were determined by examining sagittal otoliths belonging to fish sampled between November 2008 and October 2009 in the eastern Adriatic Sea (north-central Mediterranean Sea). A total of 1102 specimens (528 males, 487 females and 87 individuals of indeterminate sex), ranging from 48 to 222 mm total length were analysed. Ninety-two per cent of the otoliths were readable and 68% of the specimens had two readings in agreement. Counting of daily rings revealed that the second opaque ring represents the first annulus (315.1±27.8 daily rings). The maximum observed age was 7 years for males and 5 years for females, with males dominating in higher age classes ( > 3 years) and females in age classes 1+ and 2+. Growth was described by the von Bertalanffy growth curves and significant differences were found between males (L∞=29.10 cm, k=0.12 and t0=–1.48) and females (L∞=21.27 cm, k=0.21 and t0=–1.08). Otolith mass, length, width and thickness were determined for the otoliths belonging to 465 fish and the utility of these morphometrics as a predictor of age was evaluated. The most precise age estimations were obtained from the otolith length data, followed by the otolith mass.