Temporal changes in gonadsomatic index (GSI), hepatosomatic index (HSI), condition factor (K) and stomach content index (SCI) have been examined to reveal the annual life cycle of adult female and male Hippoglossoides dubius in Funka Bay from 1985 to 1988.
The spawning season was from January to April. H. dubius dominated the near shore and hardly took any food in this season. The spawning ground was formed at a 30-60m depth in the coastal area from the northern inner part to the southern middle part of the bay. Seasonal changes in the condition factor suggest that somatic growth occurs from May to October in males and from April to October in females.
The active feeding season was from May to July. H. dubius migrated to the southern middle part of the bay, which is probably their feeding ground. It seems that they migrated there according to their degree of food requirement. The inactive feeding season was from August to November. H. dubius concentrated in the deepest area where the cold bottom water remained (less than 7°C).