Notes on the reproduction of Squalus megalops off northeastern Brazil

The reproduction of Squalus megalops was studied using 324 specimens (275 females and 49 males) collected during a fishery-independent survey between 1997 and 2002 off the northeast coast of Brazil. The sex ratio was strongly biased toward females (1:5.6), which encompassed a larger size range (43–89 cm total length, TL) than males (31–64.5 cm TL). Significant sexual dimorphism was detected for total and eviscerated weights, with females heavier than the same-sized males. Based on development of the reproductive tract, 50% sizes at sexual maturity were estimated at between 43 and 46 cm TL for males and 59 cm TL for females. Ovarian and uterine fecundities ranged between 1 and 8 with means ± S.D. of 3.84 ± 1.45 eggs and 4.12 ± 1.37 embryos. No significant bias in the sex ratio of embryos was detected. Follicle development in gravid females occurred simultaneously with the growth of embryos, indicating that females are ready to ovulate immediately after parturition. The presence of near term gravid females throughout most of the year suggested aseasonal reproduction.