耳石日周輪解析による東部瀬戸内海産イカナゴ仔稚魚の成長

抄録

In order to improve the accuracy of growth rates prediction in larval and juvenile Japanese sand lance Ammodytes personatus, growth analysis in body length using otolith microstructure was carried out. Because the widths of the rings near the center of otoliths are very narrow, we used a scanning electron microscope together with a biological microscope. In laboratory reared larvae, growth trajectories of body length back-calculated by the biological intercept method corresponded with those measured directly by periodical sampling. This result supports that application of this method to the growth trajectories of natural A. personatus is adequate. Upon application of the method to the fish caught by commercial boat seine fishery on the opening days of fishing seasons in 1997, 2000, 2001, and 2004, the growth in early life history of the A. personatus showed logistic-like trajectories. There was a strong correlation between growth rate at the 37th day after hatching (0.64–0.88 mm day^-1) and mid-layer water temperature in Osaka Bay during early-February. Hatching dates estimated by counting otolith daily growth increments agreed with those estimated by field investigations on mature adult fish in each year.