Abstract
To elucidate the recruitment and movement process of larval ayu in the surf zone of a sandy beach facing Tosa Bay, 31 collections were made with a small seine net at intervals of approximately 5 days from November 1990 to April 1991. On the basis of seasonal variations in larval abundance, size, age, duration of residence, and the occurrence patterns of ayu in the surf zone, larval ayuwere classified into two groups: short-term resident (<30 days in duration) and long-term resident (90-120 days). The former appeared in the surf zone abundantly from mid-November to mid-December and resided there for about 1 month until they reached approximately 25 mm BL. It is likely that larval ayu (short-term resident), which recruit abundantly to the surf zone, expand their distribution offshore at approximately 25 mm BL. In contrast, the latter group were found after mid-December, and the population size was markedly small although they stayed continuously in the surf zone for 3-4 months until they reached approximately 40 mm BL.
