Reproductive biology of a bathyal hermaphrodite fish, Bathypterois mediterraneus (Osteichthyes, Ipnopidae) from the south-eastern Sardinian sea (central-western Mediterranean)

The reproductive biology of the bathyal hermaphrodite Bathypterois mediterraneus is described based on 348 specimens caught during experimental trawl surveys carried out between 800 and 1600m depth off the south-eastern Sardinian Sea (central-western Mediterranean). Based on macroscopic and histological gonad analysis and monthly variation of GSI, the female component of the tripodfish shows a reproductive season from March to May. The male component shows, instead, a longer spawning period probably guaranteeing continuous spermatogenesis at any time of year. The oocyte size-frequency distributions in mature component indicated that the species exhibits a synchronous-group and monocyclic ovary characterized by deposition in a single batch of eggs per year (total spawner). The species has a late size at first maturity (L50) of 119mm standard length (SL); the smallest mature specimen was 110mm SL