Sexual maturation, annual reproductive cycle, and spawning periodicity of the shore scorpionfish, Scorpaenodes littoralis

The ovarian structure, sexual maturation, annual reproductive cycle, and sp awning periodicity of the shore scorpionfish, Scorpaenodes littoralis, in U chiura Bay, central Japan, were examined using specimens collected between May 1995 and March 1998 and fishes reared in laboratory. The ovarian stroma and blood vessels run longitudinally through the center of each ovarian lo be. The ovarian peduncles radiate from the central stroma. During the spawn ing season, gelatinous material is secreted from the epithelia of both the ovarian peduncle and ovarian wall, and the epithelia show morphological cha nges accompanying the ovarian maturation cycle. The minimum standard length at maturity was 55.2 mm for males and 40.2 mm for females. Males with matu re testes were collected from March to November. Females in the mature or p ost spawning stages were collected between May and October, when the mean g onadosomatic indices were also high. This indicates that the spawning seaso n of this species occurs between May and October. Four successive types of oocytes were grouped in the mature ovary, comprised of mature, late and ear ly vitellogenic and previtellogenic oocytes respectively, suggesting that t his species is a multiple spawner. Four captive females spawned repeatedly at intervals of 2-8 days over a prolonged period (4-8 months); a 2-day spaw ning interval was the most common for all females. This suggests that femal e S. littoralis have a 48-h spawning cycle in captivity.