Abstract
The number of growth rings was counted on broken and burnt otoliths of eight Lethrinus spp. from two local populations: Lethrinus atkinsoni, L. harak, L. miniatus, L. nebulosus, L. obsoletus, L. ornatus, L. ravus, and L. rubrioperculatus, collected from 1985 to 1996 in waters off the Ryukyu Islands. Growth rings were revealed to be formed annually from about October to June by marginal analysis. In addition to obtaining the three parameters in von Bertalanffy growth equation and the maximum age in specimens, the relationship between age and both ovarian maturity rate and sex ratio (percentage female) was analyzed. The age at 50% of ovarian maturity was the lowest at 1–2 years old in L. harak, L. ravus, and L. rubrioperculatus and was the highest at approximately 4 years old in L. nebulosus. The age at which the sex ratio decreased to 50% due to sexual transition from female in protogynous hermaphrodite species was the lowest at 3–4 years old in the L. atkinsoni Okinawa population and was the highest at 7–8 years old in L. miniatus. The oldest maximum age for specimens was 26 years in L. nebulosus and the youngest maximum age was 12 years in L. ornatus.
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