Reproduction and feeding of spotted gully shark, Triakis megalopterus, off the Eastern Cape, South Africa

The spotted gully shark, Triakis megalopterus, was sampled opportunistically over a 12-year period from catches of shore and ski-boat fishermen using hooks and lines. Most specimens (89.6%) were taken from rocky reefs less than 10 m deep, 8% were caught at 11-20 m, and only 2.4% were recorded from waters more than 20 m deep. The reproductive biology of 35 males and 87 females was examined. The spotted gully shark exhibits aplacental viviparity. Size at 50% maturity for males is ca. 1320 mm total length (TL) and for females ca. 1450 mm TL. Maximum sizes recorded here were 1520 mm TL for males and 2075 mm TL for females. Gestation appears to last 19-21 months. The female reproductive cycle may be 2-3 years, depending on the time between pregnancies. The sex ratio of embryos was found to be 1:I but the postpartum male:female ratio was 1:2.5. Size at birth was estimated to be 420-450 mm TL. The smallest free-swimming individual recorded was 576 mm TL. Number of embryos per pregnancy ranged between 5 and 15, with a mean of 9.7. A total of 110 stomachs were examined in the feeding study. Diet changed with increase in shark size. Small sharks (<1 m) preyed mainly on Cape rock crabs, Plagusia chabrus (78% of mass), whereas sharks of 1-1.4 m preyed largely on Cape rock crabs (48%) and cephalopods (33%). Teleosts were more important for sharks larger than 1.4 m (54%); most of these prey were associated with rocky reefs.