Reproductive biology of the Brazilian blind electric ray Benthobatis kreffii (Chondrichthyes: Narcinidae )

Abstract

This study provides information on the reproductive biology of the Brazilian blind electric ray Benthobatis kreffli, endemic to southern and southeastern Brazil. Individuals were caught by bottom trawl carried out in 2003 and 2007. at 492-501 m depth off the Sao Paulo State continental slope. A total of 152 females (115-299 mm) and 144 males (91-243 mm) were sampled. Maturity was first observed at 177 and 162 mm, with total length at 50% maturity of 191 and 176 mm in females and males respectively. Uterine fecundity ranged from 1-3 and was not related to female total length. Size at birth estimated from the largest near-term observed embryos and smallest free-swinuning ray was 91-100 nun. The low fecundity observed is typical of deepwater elasmobranch species, as well as late maturity in comparison with costal species. The relatively large size-atbirth suggests that this species invests more in length of each embryo than in litter size, increasing the offspring's survival chance. In this context, these parameters highlight the vulnerability of this and other deepwater species to non-natural death, mostly caused by deep-sea fisheries.