Copyright © The Oceanographic Society of Japan. Age and Growth of Sillago aeolus in Okinawa Island,

In a study of the age and growth of Sillago aeolus, a total of 414 fish were collected from December 2000 to March 2002, around Okinawa Island. Ages of 403 specimens were determined by otoliths. Monthly changes in the percentage of otoliths with an opaque zone in the outer margin indicated that an opaque ring formed once a year, occurring between February and May. The rings can therefore be defined as annual rings. Ages of females were estimated to be 0+ to 4+, while those of males were 0+ to 2+. The von Bertalanffy growth curves were well fitted to age-standard length data of males and females, as follows: Male: Lt = 209.6 [1 – exp{–0.70 (t + 0.58)}]. Female: Lt = 297.7 [1 – exp{–0.42 (t + 0.61)}]. characters of S. aeolus, and Ohta (unpublished data) has described its spawning season on the basis of the occur-rence of larvae and juveniles in the surf zone of Okinawa Island. Age and growth information is essential for a com-plete knowledge of the life history characteristics of a population, i.e. growth rates, age and size at sexual ma-turity, mortality rate, and average life span, etc. These data are in turn used in stock assessment models and ulti-mately in fishery management of (Newman and Dunk, 2002). To date, no study on the age and growth of S. aeolus has been performed using either scales or any hard tis-sues. The objective of this study was to clarify age, growth rate, size and age composition of S. aeolus using otoliths. 2. Materials and Methods A total of 414 fish were collected from Decembe