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Growth of Pacific saury Cololabis saira (Brevoort) inhabiting the western North Pacific wasstudied based on counting daily growth increments with a scanning electron microscope (SEM). The small-size group (knob length: 200-240mm), medium-size group (knob length: 240-280mm) and largesize group (knob length: >280mm) showed increments of 256±26.0 (S. D.), 405±76.1 and 566±48.2, respectively. Based on daily growth increment formation, we determined that the ages of the 3 groups were about 8, 13, and 19 months. Small- and large-size fish were considered tohave been hatched from autumn to winter, and medium-size fish from spring to summer. The oldest specimen of Pacific saury examined in this study was about 23 months of age; thus, the lifespan of Pacific saury in this area seems to be at least 1.5 years. |
