AGE AND GROWTH OF PACIFIC SAURY COLOLABIS-SAIRA (BREVOORT) IN THE WESTERN NORTH PACIFIC-OCEAN ESTIMATED FROM DAILY OTOLITH GROWTH INCREMENTS

Growth of Pacific saury Cololabis saira (Brevoort) inhabiting the west ern North Pacific was studied based on counting daily growth increment s with a scanning electron microscope (SEM). The small-size group (kno b length: 200-240 mm), medium-size group (knob length: 240-280 mm) and large-size group (knob length: > 280 mm) showed increments of 256+/-2 6.0 (S.D.), 405+/-76.1 and 566+/-48.2, respectively. Based on daily gr owth increment formation, we determined that the ages of the 3 groups were about 8, 13, and 19 months. Small- and large-size fish were consi dered to have 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 Pacifi c saury in this area seems to be at least 1.5 years.