Geographic variation in growth of the starspotted dogfish Mustelus manazo from five localities in Japan and Taiwan

Geographic variations in growth of the starspotted dogfish Mustelus manazo from five localities off Japan and Taiwan were examined from centrum analys is using soft x-radiography. Based upon seasonal centrum edge analysis, dar k rings were formed annually, during the period of June and July in all loc alities. It was suggested that ring formation did not vary among localities , although seasonal variations in water temperature differed among localiti es. Great variations in maximum ages among localities were found. The diffe rences in maximum ages between the northernmost population, Aomori, and sou thernmost population, Taiwan, were almost two times for both sexes (male, 5 -9; female, 9-17). Females grew to a larger size than males and were appare ntly longer-lived in all localities. The significant sexual differences in growth were found in Maizuru and Shimonoseki. For both sexes, Aomori was th e largest length at each estimated age in five localities, and Taiwan was t he smallest. The growth differed in all localities for males and most local ities for females significantly, however, for females, no significant diffe rences between Tokyo Bay and Shimonoseki, and Tokyo Bay and Taiwan were fou nd. The specimens tended to grow larger and have longer life span in the ea stern and northern areas, however, the water temperature may not be a major factor for differences in growth.