GONADAL CYCLE OF PEARL OYSTER, PINCTADA-FUCATA (GOULD) IN NORTHEAST PERSIAN-GULF, IRAN

The annual cycle of gonad development and spawning in the pearl oyster , Pinctada fucata (Gould), in Nakhiloo, Northeast Persian Gulf, was in vestigated over the 15-mo period from November 1994 to January 1996. G onadal condition was assessed from criteria developed from histologica l preparations of randomly collected individuals of all sizes to descr ibe gametogenic development Gonadal development and spawning trends we re similar in both sexes. A bimodal gametogenic pattern with summer an d autumn spawning periods occurred. Gametogenesis commenced in Novembe r to December, followed by major gonadal maturation during February to April. Summer spawning was observed from April to July, with major sp awning at the latter end. During the spawning peak in July, low levels of gametogenesis were noticed. Gametogenic activity increased in Augu st to September, followed by autumn spawning from September to Decembe r. Toward the end of the spawning season, the incidence of gonadal ina ctivation increased. Minimum levels of gonadal activity were observed in November. Temperature regimen appears to have an influential role i n the regulation of gametogenic and spawning processes. P. fucata was found to be a protandrous hermaphrodite that matured as a male at shel l height greater than 20 mm. Bisexuality was uncommon, and the sex rat io was near 1:1.