Reproductive biology of catsharks (Chondrichthyes: Scyliorhinidae) off the west coast of southern Africa

Abstract

Abstract This study presents information on the reproductive biology of five southern African catshark species: Apristurus microps, A. saldanha, Apristurus sp., Galeus polli, and Scyliorhinus capensis. They were caught between Walvis Bay, Namibia, and Cape Agulhas, South Africa, from 50 to 1016 m deep. The reproductive mode of four species was oviparous, whereas G. polli exhibited aplacental viviparity. Males of all species attained first maturity slightly larger than females, and males of the four oviparous species attained a larger LTmax than females. The length at 50% maturity was similar for males and females in most species. All species matured at an LT > 75% of LTmax except for male Apristurus spp. and female G. polli, which matured at 71.2% and 68.8%, respectively, of LTmax. The egg case of A. microps has minute tendrils, whereas those of S. capensis were quite long, suggesting different egg-laying habitats. Fecundity in G. polli ranged from 5 to 13, and litter size increased in relation to increased female length. Embryos of G. polli were large, each measuring approximately 30% of female LT. Neonates of G. polli were common and appear to have a demersal lifestyle; those of the four oviparous species were entirely absent from the study. Gravid A. microps were found in summer and winter, indicating a protracted breeding cycle, but reproductively active S. capensis were caught only in winter. Prior to this study, reproductive information on these catsharks was largely lacking.