reproductive biology of centrophorus cf. uyato from the cayman trench, jamaica

Abstract

the taxonomy of the genus centrophorus (squaliformes: squalidae) is currently in a great deal of uncertainty. the characteristics of the species subject to the present study most closely resemble those of centrophorus uyato, hence the use of centrophorus cf. uyato, though the species in question may be a species of centrophorus that has not been described previously. specimens were obtained via vertical and horizontal longline at depths of 250–913 m. the reproductive biology of 51 female and 8 male centrophorus cf. uyato were examined. this species is sexually dimorphic, with females attaining a larger size than males. the smallest mature male was 81.2 cm total length whereas the smallest mature female was 91.5 cm total length. females are aplacentally viviparous, with the pups acquiring nutrition via large external yolk sacs, and there was a maximum of two pups per litter. oocytes continued to develop throughout gestation. most females carrying developing embryos had two large (>3.3 cm), equally developed ovarian oocytes, which leads us to believe that they ovulate soon after parturition. this species seems to exhibit complete sexual segregation during the non-breeding season, with mature males absent from the study site during summer months. centrophorus cf. uyato may have one of the lowest fecundities among sharks, giving birth to a maximum of two pups every three years. all species in genus centrophorus have small litters (<6) making them vulnerable to over-exploitation.