Vertebral centrums of Japanese dogfish Mustelus manazo which were caught in the East China Sea between July 1975 and February 1977 and collected at Nagasaki Fishmarket were used as the materials for age-determination and growth studies. One ring is formed once a year in both sexes from March to June. Von Bertalanffy growth equation of this species which was obtained by Allen's method is:
L_t=71.4[1-exp(-0.695(t+0.734))]for males
L_t=88.6[1-exp(-0.379(t+1.133))]for females
where L_t is the total length in cm at age t and t is age in years. Estimating from growth curves, the sexual maturity of this species is at the age of two or three years in males as well as in females. The relationship between the total lengthL (cm) and the body weight W(g)is: W=6.41×10^-3L^2.8524 for males and W=9.98×10^-4L^3.3093 for females.