Reproductive biology of the pelagic stingray, Pteroplatytrygon violacea (Bonaparte, 1832), in the equatorial and south-western Atlantic Ocean

摘要

From October 2005 to March 2010, a total of480 pelagic stingray, Pteroplatytrygon violacea, specimens, 188 females and 292 males (0.64 female: 1 male), were taken in the equatorial and south-western Atlantic by the commercial tuna longline fishery and their reproductive biology was studied. Disc widths (D_w) ranged from 28.0 to 66.0cm for females and from 34.0 to 59.6 cm for males. Size at first sexual maturity was estimated at ~48.0 cm D_w (first pregnant female) for females and ~41.0cm D_w for males. Ovarian fecundity, considering only follicles larger than 0.5 cm in diameter, ranged from 1 to 17 follicles per female, while the uterine fecundity of embryos in pregnant females in Stages 2 and 3 ranged from 1 to 5 embryos per female. The sex ratio between the embryos was almost equal (1.08 female: 1 male) and the size at birth was 19.0 cm D_w.