Abstract
Life history parameters (growth pattern, the length of the spawning season and age at sexual maturity) of Apogon lineatus were investigated from three localities in Japan. The maximum ages were found to be 3 years in Tokyo Bay, 2 years in Osaka Bay and 5 years off Niigata Prefecture. Both sexes from Tokyo Bay grew to larger sizes between the ages of 1 and 2 years than both sexes from otherlocalities, food availability being suggested as the major factor for differences in growth. Spawning seasons were during 4 months (July-October) in Tokyo Bay and Osaka Bay, but were found to only occur during the two months of July and August off Niigata Prefecture. Factors that could limit the spawning season off Niigata Prefecture were not determined. Age at maturity for both sexes inall localities appeared to be 1 year. We could not elucidate whether these variations in life history parameters arose from genetic differences or from phenotypic plasticity. In either case, the trade-off between the maximum age and the length of the spawning season in the off Niigata Prefecture population and any other population may be interpreted as an adaptation to local conditions, such as with the off Niigata Prefecture population.
