Southern Cross University has completed a limited study on behalf of Parks Australia in the Cod Grounds Commonwealth Marine Reserve to give us a better idea of how the reserve and management actions are contributing to protecting this important aggregation site for the east coast population of the critically endangered grey nurse shark. The reserve was first proclaimed in 2007 and is located in Commonwealth waters just south of Port Macquarie, NSW.
The study found preliminary evidence that the conservation benefits of the reserve included enhanced diversity, target fish abundances and grey nurse shark prey densities compared to areas open to fishing outside the reserve. On average 29 per cent greater species richness was found in the reserve compared to the surrounding reef area open to fishing with wrasses, breams, drummers and sharks and rays contributing strongly to this pattern. Four individual grey nurse sharks were observed in the reserve during the survey and none were seen in areas open to fishing.
Complementary wildlife surveys were undertaken by NSW Department of Primary Industries divers at Pimpernel Rock, located in the Solitary Islands Commonwealth Marine Reserve off Coffs Harbour, northern NSW. Divers observed 11 grey nurse sharks with a good mix of male and female. At least six of these sharks appear to be new on the Grey Nurse Shark Watch database. The largest, a mature female with numerous mating scars, is on the database and was also photographed at the Wolf Rock aggregation site off the Queensland coast in 2008 and 2014.
During the Pimpernel Rock survey, divers observed minimal fishing line and abandoned anchoring equipment at the site and none of the sharks were ‘carrying’ fishing gear (a term used when fish have picked up or become entangled in fishing equipment they can’t remove). This was a very different picture from the amount of refuse removed from this site in 2003 and 2004. This is great for the sharks and other species that visit or call Pimpernel Rock home, and may reflect the presence of our marker buoy which was installed in 2013 to let marine users know they are in a sanctuary zone, together with our continuing on-water presence in the reserve.
A listening station has also been capturing the sharks’ activity. Since being placed at the site in 2013 it has detected nine tagged sharks. This is almost a third of all the tagged sharks on the Australian east coast – a really promising number that confirms Pimpernel Rock’s status as an important site for the species.
Until recently, the grey nurse shark had an undeserved reputation in Australia as a man-eater but the species is not a threat to divers or swimmers unless provoked. Only around 1365 east coast grey nurse sharks are thought to remain. Important aggregation areas at the Cod Grounds and Pimpernel Rock off the NSW north coast are sanctuary zones so no fishing is allowed in them.
Our reserves at Cod Grounds and at Pimpernel Rock in Commonwealth waters complement protected aggregation sites in state waters across the known range of this species along the eastern coast of Australia, such as Wolf Rock just north of Double Island Point that is part of the Great Sandy Marine Park and the northern most known aggregation site of these sharks in Queensland waters, protected areas in the Port Stephens Great Lakes Marine Park off the mid-NSW coast and in the Batemans Marine Park off the far south coast of NSW.
Parks Australia’s active management of these reserves, including our ongoing support for research into this species, contribute directly to the 2014 National Recovery Plan for the Grey Nurse Shark.
Fiona, Commonwealth Marine Protected Areas
Parks acknowledges with thanks contributions from Brendan Kelaher (SCU) and Hamish Malcolm (NSW DPI).