Reproductive parameters of the commercially exploited deep-water shark, Deania calcea (Centrophoridae)
Little information is available on the reproductive parameters of the commercially exploited deep shark Deania calcea (Lowe, 1839). Samples were obtained from deep-water longlines operating at depths around 1450 m in the Portuguese continental slope between September 2008 and July 2009. Both the male and female reproductive tracts were morphologically and histologically analysed. Females were more numerous than males, which may be related to possible sex segregation by depth/geographical area and/or fishermen preference for females (larger and heavier). Reproductive indices (gonadosomatic index, oviducal gland width) as well as the fecundity and length at first maturity were estimated. The ovarian and the gestation period showed asynchronous cycles. The analysis of both the gonadosomatic index and the oviducal gland width showed evidence for the existence of two periods of high ovulation (March and September). The ovarian fecundity ranged from 7 to 17 follicles while the uterine fecundity ranged from 3 to 5 embryos. The length at first maturity estimated for females was 96.6 cm. In total 72 embryos were sampled, with total length varying between 96 and 309 mm; embryos considered to be fully developed presented the external yolk sac totally depleted and ranged between 251 and 309 mm.