Last month scientists from the CSIRO Wealth from Oceans National Research Flagship fitted acoustic tags to 50 gulper sharks, swellsharks and green eye dogfish near Port Lincoln, South Australia.
They will track the shark’s movements in a closed area designed to protect the gulper shark – a species which is severely depleted over much of its range and is nominated for protection under the Environment Protection and Biodiversity Conservation Act 1999.
“Half of the fish harvested in Australia’s south-east fishery come from a thin belt of water along the south-eastern continental shelf at depths of 200-700 metres,” says CSIRO Wealth from Oceans Flagship scientist, Dr Alan Williams.
“This rich belt yields prime table fish such as blue eye trevalla and pink ling, but is also home to several shark species vulnerable to over-fishing.
“The fishery has taken steps to reduce its impact on sharks by putting in place a network of three closed areas located off South Australia, Tasmania and New South Wales.
“To assess the optimum size and location of such areas, we need to know how much time the sharks spend there, what the seabed habitats are like, and what role they play in the ecology of the sharks. For example, the sharks may rely on shelter in rough habitats, and these are scarce.”
The research applied tagging techniques never before tested at such depths and developed new handling practices to minimise stress caused by the tag and release process.
The closed area, which covers approximately 1200-square-kilometres and is mostly in 200 to 1000m depths, was mapped from the Marine National Facility Research Vessel Southern Surveyor. Multi-beam sonar was used to draw the contours of steep rocky banks, narrow muddy terraces and submarine canyons on a previously blank area of seabed.
A towed underwater camera system was used for fine-scale observations of seabed habitats and communities, fish behaviour and habitat use, and to estimate fish distribution and abundance. In collaboration with the University of Western Australia, baited video cameras were also used to estimate fish abundance.
The sharks were caught and tagged from the South Australian Research and Development Institute (SARDI) Marine Research Vessel Ngerin, with fishing assistance provided by scientists from the Australian Maritime College National Centre for Marine Conservation and Resource Sustainability. Some sharks were released at the surface while others were lowered to the seabed in large cages fitted with video surveillance systems to monitor their recovery.
The sharks will be tracked for the next three years by a network of 24 acoustic listening stations moored 100 metres off the complex and steep seabed. These listening stations were deployed with pinpoint accuracy using the precise positioning capabilities of the Marine National Facility. Four listening stations raised for an early preview have detected a flurry of activity, receiving 5700 acoustic ‘pings’ in five days from 42 of the sharks moving in all directions.
“This large scale experiment, the deepest of its kind in the world, will be important to understand the balance between maintaining fisheries, and protecting the marine ecosystem,” Dr Williams says.
CSIRO initiated the National Research Flagships to provide science-based solutions to Australia’s major research challenges and opportunities. The nine Flagships form multidisciplinary teams with industry and the research community.
Bryony Bennett | EurekAlert!
Despite government claims, orangutan populations have not increased. Call for better monitoring
06.11.2018 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig
Increasing frequency of ocean storms could alter kelp forest ecosystems
30.10.2018 | University of Virginia
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
09.11.2018 | Event News
06.11.2018 | Event News
23.10.2018 | Event News
16.11.2018 | Physics and Astronomy
16.11.2018 | Physics and Astronomy
16.11.2018 | Life Sciences