Swellnet Dispatch Playing Tag With White Sharks

In: Swellnet Dispatch by Stu Nettle 2 Comments Sun 31st Jan '10

Tags: kent stannard , white tag research , sharks

click to enlarge

click to enlarge

click to enlarge

Kent Stannard from Whitetag reports on the latest shark activity around the nations coastline...

With recent reports of white sharks in Port Phillip Bay and a juvenile white shark biting an oar belonging to a surf club boat in NSW, it makes me realise how much more we need to know about where sharks go and what they do.

The technology to track the movements of white sharks and see how they use the ocean has progressed enormously in the decade since CSIRO pioneered satellite tracking on two small white sharks - anyone remember Neale and Heather - in Victorian waters a decade ago.

One of the more recent developments has been installing listening stations around the Australian coastline that 'listen' for special acoustic tags placed on or inside white sharks. These tags can last up to ten years and send out a unique coded signal that the station records when a shark comes in range (usually about 400-500m). Researchers are now tagging many different types of sharks and fish with these devices and studying their movements around Australia using this system.

During our trip to Port Stephens last year, CSIRO researchers Barry Bruce and Russ Bradford used both satellite tracking tags attached to the shark's dorsal fin and acoustic tags that they carefully implanted in each shark's belly via a small incision. Some of those white sharks have now swum down the coast and are now in waters off the coast of Ninety Mile Beach and Corner Inlet - exactly where Neale and Heather were at this time of year.

The difference for these sharks is that their acoustic tags will help the researchers follow their movements for many years to come as they grow into large sharks via the growing number of listening stations located in Australian waters. Already these stations have recorded large sharks moving from South Australia to northwest Western Australia and central Queensland as well as juveniles moving north and south along the NSW coast over multiple years - over much longer periods than satellite tags alone can give.

Now imagine combining the two technologies in one unit - satellite tracking and acoustic tagging.

Well, our friends at CSIRO have done just that. In collaboration with a company in Canada, CSIRO have been trialling a special listening station (called a VR4) that, on recording a tagged shark, sends a message via the Iridium satellite system to let researchers know it is in the area.

I was fortunate enough to be on board the vessel with Barry Bruce and Russ Bradford when they were trialling this system off the Neptune Islands in South Australia back in 2007. Because the sharks there are much larger (3-5 m) than the juveniles at Port Stephens, Barry and Russ used an Hawaiian sling to dart the tags onto the backs of the sharks rather than catch them and do so by surgery.

 The trials have been so successful that recently the Western Australian Government has deployed twenty of these hi-tech satellite linked listening stations off Perth's beaches. The WA Department of Fisheries is collaborating with CSIRO in the research to learn more about how white sharks use the Perth metropolitan coast. The system sends messages via email to a network of Government authorities, community groups (such as Surf Life Saving Australia) and local councils responsible for implementing the Western Australian Shark Incident Emergency Response Plan, notifying them of when and where a tagged shark is detected.

Of course the system only tracks tagged sharks, but the more the researchers tag, and the more this type of technology is placed around Australia?s coast, the more we will understand about why sharks visit certain beaches at certain times. Perhaps we will one day see a regular shark report on Swellnet based on fact instead of media-hype! //KENT STANNARD

Loading Comments