Settlement and Migration of Early Stage Spangled Emperor, Lethrinus nebulosus(Pisces: Lethrinidae), in the Coastal Waters off Okinawa island, Japan.

Abstract

Settlement and migration of the early life stage spangled emperor were studied in the Hanechi region off the northern part of Okinawa island from 1984 to 1991, by means of underwater observations with SCUBA, samplings of juveniles gathered by lamp and with seine, and also release and recapture experiments of hatchery-reared juveniles.Juveniles just after settlement, about 17mm in fork length (FL), were first observed in seagrass beds shallower than 3m depth in May and increased in number through July. After August they gradually moved out of the seagrass beds and disappeared after November. Samplings with fish-lamp and seine revealed that a peak of juvenile settlement took place in June, although a few individuals just before settlement were caught as late as in October. The reared juveniles, which were tagged and released in November when they were 5-6 months old and 104mm in mean FL, stayed within 3km of the release point until June of next year, and expanded their distribution range to the outer edges of the coral reef facing the open sea, which was 7km distant from the release point, in October.