Age and growth of pleuronectid flounder Hippoglossoides dubius in Funka Bay, Hokkaido [Japan]

Otoliths obtained from 1004 specimens of pleuronectid flounder Hippoglossoides dubius were examined in order to validate aging method. Samples were collected by otter trawling in Funka Bay from November 1982 to December 1983, and from November 1985 to September 1986. From the seasonal change in the percentage of otolith with translucent edge and marginal growth rate, it was confirmed that the translucent zone of the otolith was formed annually in winter. Based on the relationship between the radius of the otolith and the standard length of H. dubius, and the distances from the focus to the outer margin of succes-sive translucent zones, average growth was estimated as follows; November 1982-December 1983 male: SLt=233.1 [1-exp (-0.1630 (t+1.0346))] female: SLt=433.0 [1-exp (-0.0624 (t+1.5759))] November 1985-September 1986 male: SLt=240.8 [l-exp (-0.2522 (t+0.3195))] female: SLt=294.8 [1-exp (-0.2147 (t-0.1468))] SLt: standard length in mm at age t years Annual change in age composition showed that the year class strength of H. dubius in Funka Bay considerably fluctuated and strong year classes were formed in 1973, 1980 and 1983.