1Hokkaido Research Organization Central Fisheries Research Institute, Yoichi, Hokkaido 046-8555, 2Hokkaido Research Organization Wakkanai Fisheries Research Institute, Wakkanai, Hokkaido 097-0001, 3Field Science Center for Northern Biosphere, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan
There is a need to establish a method of determining age and to investigate the relationship between the age and body size of the Northern Hokkaido stock of the Arabesque greenling Pleurogrammus azonus. Therefore, we examined the method of age validation by using otoliths, and estimated the relationship between age and size. A mass-processing method was used to section the otoliths. The annual growth of otoliths was verified using edge-type analysis. The age of individual fish could be accurately validated by counting the number of outer edges of the translucent zones. Because of disagreement between the annual growth of otoliths and the formation of checks, the number of checks was considered unsuitable for age validation of the stock. Logistic growth models, which indicated differential asymptotic length by sex, were estimated as the age-size relationship of the stock. The growth of the Arabesque greenling was rapid up to 2 years of age, then slowed. We conclude that age validation is necessary for the stock because it is impossible to predict the age of the fish on the basis of size after 2 years of age.