Barker, S.M., Peddemors, V.M. and Williamson, J.E., 2011. Recreational SCUBA diver interactions with the critically endangered grey nurse shark Carcharias taurus. Pacific Conservation Biology, 16: 261–269.

Summary

Grey nurse sharks are a popular tourist attraction for divers as they are large and ferocious-looking yet pose no threat to humans. However, grey nurse sharks are also listed as Critically Endangered for the east coast of Australia. Careful management strategies are needed to reduce human-induced impacts, one of which may be potential departure from preferred aggregation areas following harassment by SCUBA divers.

This study is the first to monitor the activities of SCUBA divers at a grey nurse shark aggregation site and relate these to shark behaviour. The research was conducted at Magic Point off Maroubra, Sydney.

We found that divers temporarily affect the behaviour of grey nurse sharks, but their behaviour rapidly return to pre-diver levels once the SCUBA divers left the area. Sharks reacted to divers by changing their distribution within the Magic Point cave and sometimes leaving the area.

Overall, divers obeyed the voluntary Code of Conduct when diving at this grey nurse shark aggregation site, with large groups (=12 divers) never entering the cave, suggesting obedience to their Dive Leader’s instructions. Medium sized groups did enter the cave, but never into the left side. Small groups of divers (=4 divers) observed the sharks from all zones and approached the cave closer than larger groups, possibly as these were often underwater photographers. Although these small groups only represented 4% of the total time observing sharks at this site, they had a disproportionate impact as they invaded the main aggregation site on the left side of the cave. These data highlight that individual diver activities need to be taken into consideration when managing diver-shark interactions.

This study suggests that the current voluntary Code of Conduct is generally adhered to, particularly by the organised charter operators with large client groups, but that more education is required to reduce the impact of recreational divers. Although this impact appears to be short-term in nature, adherence to maintaining a distance between diver and shark will ensure longer and better viewing opportunities whilst ensuring minimal impact on the biology of this threatened species.