カイワリ(白手メッキ)

This study investigaled the optimal hard structure for use as a marker in age determination from eight hard structures, and age and growth of the whitefin jack Kaiwarinus equula. Specimens were collected in the East China Sea during the period from April 1996 to March 1997. Length frequency distributions showed that most specimens of both males and females ranged from 165 to 185 mm in fork length (FL). Vertebral centra were chosen as the optimal hard structure for use as a marker in age determination among the vertebral centra, scales, otoliths, opercles, preopercles, interopercles, actinosts and urohyals. Monthly changes in the frequency of appearance of a translucent band on the outer inargin of the centrum and in the marginal increments indicated that ring marks formed twice a year, from March through April and from September through October. Ring mark formed between September and October could be considered as an age mark. Male specimens possessed 2-14 ring marks while females had 2-13 ring marks. Using the back-calculated forlt lengths at the lime of age mark formation, growth of males was expressed as FLt=273(1-exp { -0.270(t+0.213) })(1? t ? 7) and FLt=272(1-exp { -0.286(t+0.111) } ) (1 ? t ? 6) for females. Our results suggested that the growth trends and lifespan of both sexes were similar.