The secret life of white sharks
Recent research has shown that the residency and fine-scale swimming behaviour of white shark can be affected by cage-diving tourism. However, it is still unknown whether those changes are positively, neutrally, or negatively impacting white sharks at an individual or population level. The aim of our project is to understand the behaviour of white sharks at the Neptune Islands in relation to natural predation/feeding and the cage-diving industry, and more specifically to:
– Record the activity of white sharks and determine their predatory/feeding strategy at the Neptune Islands;
– Compare the activity of white sharks when cage-diving operators are present and absent; and
– Assess whether the changes observed at the Neptune Islands are detrimental, positive, or neutral.
Our study will use novel state-of-the-art technology to understand how white sharks use Australia’s largest adult aggregation site. Newly developed ‘activity package’, which records bursts of speed in three dimensions, depth, and swimming speed at very high frequency (15 data points per seconds), will be deployed on free-swimming white sharks to monitor the activity and behaviour of these sharks around the Neptune Islands off South Australia. The activity package will remain on the sharks for up to seven days after which it will detach itself from the fin and float to the surface, minimising any detrimental effect on the shark.
Photo of a white shark with the activity package and example of some of the data obtained from the activity package (representing a 22 hr deployment) (Photo: Andrew Fox)
Our activity package also includes a video camera that will film similar videos to that of the National Geographic famous Crittercam. This will allow us to record the activity and movement of the sharks in relation to their behaviour as shown by the footage taken from the shark’s perspective. Thanks to this equipment, we will better understand the predatory behaviour of white sharks and how they hunt seals or fishes while at the Neptune Islands and how the shark activity relates to the cage-diving industry.
Through continuous recording by the accelerometer package and video camera, we aim to record natural predation and understand how white sharks are using this aggregation site. Although we have historically assumed that white sharks aggregate around the Neptune Islands to feed on seals hauling on the islands, natural predation around the Neptune Islands are seldom observed. This is surprising when compared to other aggregation sites such as False Bay, near Cape Town in South Africa, where white sharks can be seen predating on seals more than 30 times in one morning. This suggests that sharks either do not feed around the Neptune Islands or uses a very different feeding strategy that cannot be observed from the surface.
Example of attempted natural predation in False Bay, South Africa (Photo: Mark Enarson)
Previous studies have also shown that some of the white sharks visiting the Neptune Islands have increased their period of residency and change their swimming behaviour during cage-diving operation. However, it remains unknown whether these changes have any detrimental effects on white sharks. Although it is possible that changes in swimming behaviour increase sharks’ energy expenditure, it might also be no different to patrolling around the Neptune Islands and seeking potential preys. We will, therefore, deploy our accelerometer packages during days when cage-diving operators are present and compare these to deployments during days when the cage-diving industry do not operate. The 3D-acceleration and swimming speed data will enable to extrapolate activity of white sharks and assess whether interacting with cage-diving operators increases their energy expenditure.
(Photo: Andrew Fox)
How The Funds Will Be Used
Due to the remote location of the Neptune Islands where white sharks aggregate and where cage-diving takes place, we will need to charter a vessel that allows us to stay on site overnight to maximise the number of deployment during the intended fieldtrip. As a result, chartering of the vessel for 5 days will require substantial funding ($3,300/day = $16,500). The rest of the amount requested will be used for scientists to travel to Port Lincoln ($2,200 for 3 scientists with equipment) and for the clamps and corrodible links ($1,600) to deploy the activity package on the sharks’ dorsal fin and ensure that it detaches itself once data has been collected to reduce any potential detrimental impacts on sharks.
Activity packages (worth ~$15,000 each) will be provided at no costs through a collaboration with the National Institute of Polar Research in Tokyo, saving a substantial cost to the study. None of the funds obtained will be used towards salary or administrative costs as these will be covered by Flinders University and the organisations of our collaborators.
The hardest part of the project will be to deploy the accelerometer package on white sharks. Luckily, we will be working with the cage-diving operators who have extensive knowledge of the sharks visiting the Neptune Islands and who will help us deploying the equipment. We have also had the opportunity to test the deployment methods intended to be used and have already successfully deployed 4 mock clamps/accelerometer and 5 actual accelerometer packages as a proof of concept for our project.
I have been working on white sharks and the effects of the cage-diving industry since I moved to Adelaide 7 years ago. I previously led a research project aimed at understanding the effects of cage-diving on the fine-scale swimming behaviour of white sharks (Marine Biology paper) and also tested the efficiency of the Shark Shield electric shark deterrent (Shark Shield paper). My experience with white sharks does not limit itself to South Australia, as I have also studied these sharks in South Africa and more recently in New Zealand.
I am recognised as an international expert in the field of shark ecology and conservation, and have received seven scientific awards including one from the “Belgian Foundation of the Vocation”, the South Australian Young Tall Poppy Award which recognises Australia research excellence, and more recently Flinders University Vice-Chancellor Early Career Research Award. I am an active invited member of the IUCNs largest Species Survival Commission, the Shark Specialist Group for which I co-authored over 60 Red List Assessments. I have published 40 peer-reviewed publications, 23 reports or proceedings, over 70 scientific presentations. Since I started at Flinders University, I have supervised 11 Honours, four Masters, and three PhD students to completion and am currently supervising or co-supervising three Honours and seven PhD students. At Flinders University, I formed the Southern Shark Ecology Group, which delivers high quality research on the biology, ecology and population status of chondrichthyans, as well as assessments of their vulnerability to fishing pressure, interactions with humans and related public perception. This group also provides research-based advice to managers and policy makers on issues associated with sharks, rays, skates,
The study was developed and is being undertaken as a collaboration between Flinders University, the Institute for Marine and Antarctic Studies / University of Tasmania (Assoc Prof Jayson Semmens), and the National Institute of Polar Research in Tokyo, Japan (Dr Yuuki Watanabe and Dr Nicholas Payne).