Social organization and sexual pattern in the mediterranean parrotfish Sparisoma cretense (Teleostei: Scaridae)

We examined the social organization and reproductive pattern of a population of Sparisoma cretense L. at Lampedusa Island (Italy). During the breeding season (July to September) individuals occur either in territorial or in non-territorial groups, which quantitatively di€er with respect to use of space, sex- ratio and sexual activity. Territorial groups consist of one male plus one to three females, whereas in non- territorial groups as many as 54 ®sh share a common area. Among non-territorial groups, variations, in both sex-ratio and behavior, suggest they could represent either feeding aggregations or reproductive aggrega- tions. Spawning, always in pairs, occurs daily in a short period of time before dusk and has been observed only in territorial groups. Group spawning has never been observed, but another alternative mating tactic, streaking on pair spawning, was recorded. In the non- breeding season ®sh do not aggregate in organized social units. Histological examination of gonads showed that adults are larger than 12 cm total length. Females have an asynchronous ovary, typical of species spawning several times during the breeding season. Males show secondary testes, indicating that their go- nads develop ovaries as juveniles, which are later re- di€erentiated into functional testes. Histological and demographic data seem to indicate that, as in other species of this genus, prematurational sex-change oc- curs. The sexual pattern appears to be essentially go- nochoristic, but the potential for sex-change is not excluded.