Notes on the reproduction of Squalus megalops off northeastern Brazil

Population biology of the shark, Squalus megalops, harvested in the central-east Atlantic Ocean

“…Although this study was based on a relatively small sample with a wide TL range, the maximum TL found was considerably larger than the maximum TL described by Compagno et al (2005) and very similar to those found in South Africa and Brazil (Watson and Smale, 1998;Hazin et al, 2006). In this study, sexual dimorphism in growth was observed, with females of S. megalopsattaining larger TL than males.…”

“…The observation of females bearing eggs or embryos and females in a post-partum condition throughout the year shows that S. megalops is an asynchronous breeder, in which ovulation, parturition and pregnancy do not take place at a specific time of year (Braccini et al, 2006a). Furthermore, the results obtained suggest an ovulation-gestation period lasting approximately two years, which coincides with that indicated by Watson and Smale (1998), Braccini et al (2006a) and Hazin et al (2006).…”

“…In this study, sexual dimorphism in growth was observed, with females of S. megalopsattaining larger TL than males. This pattern has been observed in all studies of S. megalops (Watson and Smale, 1998;Braccini et al, 2006a;Hazin et al, 2006), and it is common among viviparous sharks. This observation coincides with the results obtained for the TL-Tw relationship, which shows positive allometric growth in females and isometric growth in males.…”

“…The pattern of development of the LFD suggests that the growth of the follicles and ovulation are asynchronous among individuals (Braccini et al, 2006a;Hazin et al, 2006). This is probably due to the uniform environmental conditions characteristic of the deep shelf and slope habitat occupied by S. megalops (Watson and Smale, 1998;Hazin et al, 2006).…”

“…This suggests that ovulation occurs immediately after birth. Therefore, there is continuous reproduction based on the concurrence of the ovulation and gestation cycles (Braccini et al, 2006a;Hazin et al, 2006). Additionally, the very low percentage of females in the post-partum state with a large LFD suggests that the time between birth and a new pregnancy is very short (Graham, 2005).…”