Quantitative diet assessment of wobbegong sharks (genus Orectolobus) in new South Wales, Australia

The diets of three species of wobbegong (Orectolobus ornatus, O. maculatus, and O. halei) in New South Wales, Australia, were investigated using stomach contents from specimens caught by commercial fishers. Some 80% of wobbegongs caught by commercial setline, and 60% caught by trap or scuba diving, had empty stomachs, most likely due to regurgitation. Wobbegongs were frequently hooked in the stomach (80-90% of the catch), potentially contributing to the greater proportion of empty stomachs compared with other species of shark. The diet of all three species was primarily osteichthyans, but with some cephalopods and chondrichthyans. Interspecific differences in the diets were related to total length of the shark. Octopuses were more frequent in the diet of O. ornatus (dwarf ornate wobbegong) than other wobbegong species, possibly through the smaller adult size facilitating capture of octopuses in small holes/crevices. Orectolobus halei fed more frequently on pelagic species and chondrichthyans, possibly because of their greater mobility. Wobbegongs feed at a high trophic level, and their removal from their ecosystem may impact lower trophic levels.