Reproductive biology and placentotrophic embryonic development of the smalleye smooth-hound shark, Mustelus higmani, from the south-eastern Caribbean

The reproductive biology and embryonic development of Mustelus higmani were examined between January 2015 and December 2016 in the south-eastern Caribbean. Captures comprised 813 females (23.2–72.5 cm TL), and 960 males (22.6–62.5 cm TL). The total length at 50% maturity was estimated as 47.8 and 47.5 cm for females and males, respectively. Uterine fecundity ranged from 1 to 8 embryos and ovarian fecundity between 1 and 9 vitellogenic follicles. The time of parturition and mating season of M. higmani may occur throughout the year, peaking between November and February. The presence of pre-ovulatory ovarian follicles along with advanced embryos indicates an annual reproductive cycle for female M. higmani. The main embryonic development stages were recorded in the samples, from uterine eggs (1 to 6 per female) to term embryos (23.0–26.0 cm TL). The transition between placental pre-implantation and post-implantation occurs when embryos have attained a TL of 5.0–6.0 cm. The observation of abundant uterine histotrophic secretions in late pregnant and post-partum females demonstrates that histotrophy may intensify close to birth in this species. The local population of M. higmani appears to have relatively high productivity; nonetheless, this species is heavily harvested and lacks management measures in the study area.