Abstract
Age, morphology and osteology of larval Japanese flounder settling at YanagihamaBeach, Nagasaki Prefecture in 1990 and 1991 were compared among birth months. Age and size at settlement (H stage larvae) decreased as the season advanced; from 25.2 days and 12.0mm SL to 20.4 days and 9.9mm SL in the February and April cohorts, respectively, in 1990. Then from 27.0 days and 11.3mm SL to 22.1 days and 9.5mm in the February and April cohorts, respectively, in 1991. Whereas no differences in morphometry and meristic counts of larvae were seen between monthly cohorts, the degree of vertebral ossification at settlement was greater in the February cohort than in the April cohort, suggesting inferior swimming ability in the latter.
