Shark Ecology in South Australia

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Shark Ecology in South Australia

By Charlie Huveneers

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Since I have become a scientist working on shark biology and ecology, I often meet people telling me how much their dream was to become a marine biologist and to work on the ocean. I also often hear from parents asking me about what their children should do to successfully start a career in science. The best advice I could give these people is to have initiatives, perseverance, and to stand-out from the crowd.

I first started being interested in marine biology and more specifically in sharks when I was 11 years old and had to prepare a presentation on an animal. I choose to do this presentation on sharks from which my interest kept on growing larger and larger.

Following my last year of high school, I undertook an exchange year in Australia through the Rotary International during which I learnt English and started to learn about sharks and potential opportunities. However, since I am originally from Belgium, it was logistically easier and cheaper to organise an undergraduate degree in England rather than in Australia. I was quickly accepted within Southampton University to undertake a degree in Oceanography with Marine Biology with Honours. Throughout my undergraduate degree, I maximised opportunities to volunteer and help out diverse research projects including work on basking shark in England, white sharks in South Africa, lemon sharks in the Bahamas, and pelagic sharks in the Gulf of Mexico, USA. Thanks to these volunteering experiences and high grades achieved during my undergraduate and Honours, I obtained a scholarship within Macquarie University in Sydney to undertake a PhD investigating the impacts of fishing in wobbegong sharks in New South Wales. Three and a half year later I submitted my PhD and graduated a few months later. During my PhD, I was able to re-describe a new species of wobbegongs and learn about their reproductive system, diet, age and growth, and movements. These provided me with knowledge in various areas of shark biology and ecology, opening the door to many work opportunities.

My first official job after my PhD was a short-term contract within the South Australian Research and Development Institute (SARDI) in Adelaide as shark ecologist to undertake a review of pelagic sharks occurring in the Great Australian Bight. However, after four months in Adelaide, I was offered another position back in Sydney in which I was going to be running the Australian Acoustic Tagging and Monitoring System (AATAMS). This project aimed to deploy several hundred acoustic receivers around the entire Australian coastline and tag various marine organisms including reef fishes, tuna, rays, and sharks. I worked for AATAMS for two years during which I had the opportunity to undertake fieldwork in some amazing remote areas of Australia and tagged many very different marine species.

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Once again, a great opportunity opened up with the advertisement of a new shark ecologist position and lecturer in South Australia within SARDI and Flinders University. I was successfully chosen for this position and I have now been back in Adelaide for nearly a year. As part of this new position, I have created the Southern Shark Ecologist Group (SSEG) and initiated various projects on chondrichthyes (sharks, rays, and chimaeras) with students and other collaborators. These include projects to:

–       Investigate the osmoregulation of Port Jackson embryos to assess their survival rate and physiological impacts following increased salinity levels (e.g., resulting form the outflow of a desalinisation plan). Honours project of Carlie Heaven;

–       Assess the post-release survival rate and physiological stress of stingarees following trawling capture. Bycatch levels of prawn trawling are often high and while many species are discarded by fishers, survival rate is mostly unknown. This project aims to increase our understanding of how stingarees react to capture during prawn trawling operations. Honours project of Matt Heard;

–       Test the use of fatty acid analysis to quantify the diets of elasmobranchs.  Previously dietary information of sharks was obtained from stomach contents from dead or sacrificed animals. However, stomach contents only provide information about the last meal. This study will develop a new non-lethal method to assess the diet of sharks and rays. This method uses the chemical components of food (including fatty acids) which are stored within the tissues of prey and predator. As different prey types have different proportions of fatty acids, their signatures, which are passed to the tissues of the predator, can be compared to determine diet composition of these predators. This study will be the first time fatty acid signature analysis is investigated and validated in sharks, and will enable to assess the diet of threatened and protected species such as white sharks and mako sharks from which stomach contents are difficult to obtain. PhD project of Crystal Beckmann;

–       Determine the movements and migratory patterns of mako sharks. Mako sharks are currently being tracked to improve our knowledge of their movement patterns, dive behaviour and temperature preferences. State-of-the-art technology combining pop-up tags and satellite ‘Splash’ tags are being used, providing information which will help determine links between shark movement patterns, and oceanographic and physical features. Ultimately, this project will help determine the role of these top predators in the pelagic ecosystems of Southern Australia. PhD project of Paul Rogers;

–       Quantify the impacts of fishing on whaler sharks (bronze and dusky whalers). We are beginning a project using various methods including satellite and acoustic tagging as well as biological sampling (diet, reproduction, and age and growth) in collaboration with commercial fishers to quantify the resilience of whaler sharks to the current fishing pressure. Collaboration with Paul Rogers;

–       Model the fine-scale swimming behaviour of white sharks in response to the berleying undertaking by cage-diving operators. During cage-diving activities, operators commonly use berley (mixture of minced fish and blood) to attract sharks close to the boat for viewing. Recent years have seen a marked increase in the number of days that cage-diving operators are on site from about 120 days to over 300 per year. The impact of this increase in berleying activity on the behaviour of white sharks at the Neptune Islands is unknown and requires further investigation to ensure the appropriate management arrangements are established to minimise the impacts of the cage-diving industry. At present there is very little information on how white sharks behave in the vicinity of pinniped colonies and specifically how they behave during periods when cage-dive operators are on site and berleying. Our project uses continuous tags and acoustic telemetry that enables fine-scale modeling of the swimming behaviour of the tagged sharks through continuous recording of positions and depths within one metre accuracy.

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