AGE AND GROWTH OF POINTHEAD FLOUNDER HIPPOGLOSSOIDES-PINETORUM IN ISHIKARI-BAY, HOKKAIDO

Pointhead flounder, Hippoglossides pinetorum, taken by commercial gill nets and an experimental beam trawl net in Ishikari Bay, Hokkaido from September 1991 to July 1993 were aged using polished otoliths (saggit ae). Ages were validated by the monthly change in the percentage of ot olith with translucent edge and marginal increments; a single opaque a nd translucent zone was formed annually. The regression method and Lee (Fraser-Lee)'s method were used to estimate the back-calculated lengt h. Growth of pointhead flounder was expressed as L(t)=251.9(1-exp-(0.2 61(t-0.142))) for males and L(t) =315.1(1-exp(-0.219(t-0.200))) for fe males using back-calculated lengths by the regression method and L(t) =251.6(1-exp(-0.263(t-0.142))) for males and L(t)=333.0(1-exp(-0.204(t -0.186))) for females using back-calculated lengths by Lee's method, w here L(t) is the standard length (mm) at estimated age t. Small differ ences in the theoretical lengths of older female fish were found betwe en the two methods. However, the theoretical standard lengths predicte d by the two methods were very similar at most estimated ages and indi cated the approximate actual length at each age.