Abstract:

A brief review of investigations carried out at IAMC-CNR Messina on the reproductive biology of farmed blackspot sea bream Pagellus bogaraveo, a new candidate species for aquaculture, is presented. Different aspects of sexuality, including hermaphroditism, gametogenesis, spermatozoal ultrastructure, maturity staging, seasonal development of gonads, and spawning in captivity, were studied. Protandrous hermaphroditism appeared to be the prevalent sexual pattern, although a high incidence of gonochorism occurred. Males were most abundant in smaller size classes and reached sexual maturity at 28.0 cm, while females predominated in the larger size classes and reached maturity at 29.5 cm. The reproductive season lasted from February until April, as in the natural environment. Spontaneous spawning in tank occurred occasionally, whereas approximately 50% of females produced eggs upon stripping. The remaining 50% failed to ovulate, or even to achieve oocyte maturation, indicating an impaired reproductive functionality. A high incidence of oocyte atresia was also recorded. Males produced a small quantity of highly viscous milt, containing only 3% motile spermatozoa. The spermatozoon of P.bogaraveo has an ovoid head, a midpiece containing only one mitochondrion, and a 50.64 ± 4.82 μm long flagellum, inserted perpendicularly and eccentrically into the nucleus.