SIMS

The Way of the Wobby

Date: Wednesday 02 July, 2008
By: Dr Charlie Huveneers

A new project aimed at understanding the impacts of releasing predators within Marine Parks recently started along the Sydney shore. This new study will investigate the movements and residence times of wobbegongs around Manly using passive acoustic telemetry. This relatively new technology uses acoustic receivers or 'listening stations' that can record unique identity codes sent by transmitters attached to animals such as sharks, rays or other fishes. Five of these listening stations were recently deployed within the Cabbage Tree Bay Aquatic Reserve thanks to which wobbegongs will be tracked with an accuracy of 3-10 metres.
Ten wobbegongs from the Aquatic Reserve will be captured and internally tagged within the body cavity through a small incision in the abdomen. Stitches will be applied before releasing the wobbegong with the whole surgery taking less than 5 minutes. The movements of these wobbegongs will then be monitored for a couple of months prior to releasing ten wobbegongs from Sydney Aquarium that will also be tagged prior to the release. These wobbegongs were born in captivity and part of a study looking at wobbegong growth to determine their resilience to fishing pressure.
The success of the release of captive-bred wobbegongs will be assessed through monitoring the movement of these sharks and comparing observed patterns to those of wild wobbegongs. The listening stations will also tell us if the captive-bred wobbegongs leave the Aquatic Reserve. Furthermore, the impact of the captive-bred wobbegongs on the wild population will be assessed by comparing the area of movements of the wild wobbegong populations prior and after the release of the Sydney Aquarium wobbegongs.
This study will be later expanded through tagging of various other species such as the juvenile whaler sharks occurring within the Reserve, Australian Giant Cuttlefish, Blue Gropers, and possibly Weedy Seadragons. The inclusion of these other species will help us getting a better understanding of the ecosystem impacts of releasing predators within protected areas.
This project is jointly supported by the Sydney Institute of Marine Science, Department of Environment and Climate Change, Sydney Aquarium Conservation Fund, Macquarie University, the NSW Department of Primary Industries, Australian Acoustic Tagging and Monitoring System (part of the Integrated Marine Observing System), and Defence Maritime Services.

Related Link:

IMOS - Australian Acoustic and Tagging Monitoring System