Age and Growth of the Starspotted Dogfish Mustelus manazo from Tokyo Bay, Japan

Abstract

Age and growth of the starspotted dogfish Mustelus manazo in Tokyo Bay were examined from centrum analysis using soft x-radiography. Based upon seasonal centrum edge analysis, a dark ring was formed annually, mostly in June. The von Bertalanffy growth equations were described as follows, male; Lt = 1241[1 -exp {- 0.120(t + 2.59)}], female; Lt = 1341 [1-exp{-0.113(t + 2.55)}], where Lt is total length in mm and t is age in years. The maximum age was 8 years old for males and 10 years old for females. The growth until 2 years was similar in both sexes, but over 2 years females tended to grow larger than males. Sex ratios were approximately 1:1 until age class 4; after age class 5 the proportion of males was reduced.