Assessing distribution and relative abundance of wobbegong sharks (Orectolobidae) in New South Wales, Australia, using recreational scuba-divers
Huveneers, C., Luo, K., Otway, N.M. and Harcourt, R.G., 2009. Assessing distribution and relative abundance of wobbegong sharks (Orectolobidae) in New South Wales, Australia, using recreational scuba-divers. Aquatic Living Resources, 22: 255–264.
Wobbegongs sharks have been commercially targeted in various fisheries in NSW. Over the past decade, there has been a marked reduction in the landed catch. Information on the distribution and abundance of these benthic sharks is difficult to obtain, but necessary for ecologically sustainable management of their populations. Opportunistic sightings of wobbegongs collected by recreational scuba-divers were used to assess the distribution and relative abundance of wobbegongs in NSW. Over a 19-month period, 304 dives were undertaken by recreational divers during which 454 wobbegongs were observed at various sites along the entire NSW coast. Larger numbers of wobbegongs were observed in coastal waters of northern compared to southern NSW. Spotted and ornate wobbegongs were observed in similar numbers, but species composition was highly variable among sites. Very few juvenile or newborn spotted wobbegongs were observed, whereas small ornate wobbegongs were mainly observed north of central NSW. These individuals were possibly a third, cryptic species, the dwarf ornate wobbegong. The few observations of small wobbegongs suggest that juveniles and pups may occupy habitats (crevices) that cannot be sampled by divers. Alternatively, small wobbegongs may not occupy sites that are used by scuba divers. The development of sampling techniques that mitigate this likely bias will be necessary if abundance estimates are required for future sustainable fisheries management.