Biology of the ornate angel shark (Squatina tergocellata) from the Great Australian Bight

Abstract

Ornate angel sharks were sampled from commercial catches from the Great Australian Bight trawl fishery during the period from February 1992 to February 1993. Size structure, reproduction and diet were studied. Both sexes exhibited similar length–weight relationships. Morphological data indicate that the most accurate conversion to total length (TL) would be obtained from the distance between the granular ocelli on the trunk near the pectoral fins. Males reached sexual maturity at a TL of 810–910 mm, females at 1150–1250 mm. The male:female ratio was 1:3 for the post partum population and 1:1 for embryos. Both ovaries were functional throughout the year, but the left ovary contained more ovarian follicles than the right. Follicle diameters ranged from 1 to 68 mm; the largest follicle was found during autumn, before ovulation, the smallest during spring, after ovulation. Eighteen near-term embryos from four females were observed during January and February 1993. The number of young per female ranged from 2 to 9. It appears that S. tergocellata has a minimum gestation period of 6–12 months and parturition may occur biennially. The most common stomach contents were squid (Notodarus gouldi) and fish (mainly Monacanthidae).