Age and growth of Japanese Whiting Sillago japonica in Tateyama Bay

Abstract

Age and growth of the Japanese whiting Sillago japonica were examined from 908 fish specimens collected from October 1993 to January 1995 in Tateyama Bay, and growth curves were estimated by using a new method. Monthly changes in percentage of the otolith with opaque and translucent zones in the outer margin indicated that growth ring was formed once a year. Marginal increments of otolith formed annual rings from March and April. Ages of the fish were estimated to be 2, 3 and 4 years for both sexes. Using otoliths of 532 fish, growth in total length was expressed by the combined equation of the relative growth in total length and the radius, and the growth of ring radius as Lt=602.5(1 - e-0.125(t-0.02)) for male and Lt=530.2(1 - e-0.149(t-0.04)) for female, here Lt is total length in mm and t time in year. Growth in female and male were similar. The growth equations of the new and back-calculation methods were compared, and the difference of the parameter estimates, discussed.