The Biology, Migration, and Growth Rate of the School Shark, Galeorhinus australis (Macleay) (Carcharhanidae) in the South-eastern Australian Waters.

Abstract

The school shark fishery in south-eastern Australian waters has operated on a homogeneous stock which has a low reproductive potential. The species is slow-growing; the smallest mature males (120 cm) are over 8 yr of age and the smallest mature females (135 cm) are at least 2 yr older. The gestation period is approximately 6 months and it is estimated that only about half the female population bear young each year. Each gravid female carries 17-41 young with a mean number of 28. The lengths of the normal full-term embryos range from 280 to 350 mm with a mean for both sexes of 300 mm. The larger females tend to have the longest embryos. Slightly more male than female young (54 : 46) are born. Because the inshore populations of juveniles have been dwindling and the size of the older stock is decreasing, it is believed that this slow-growing species is being overfished. Measures aimed at protecting school sharks in their vulnerable stages have been proposed. Any conservation programme will be long-term as this shark has such a low reproductive capacity.