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Scotty88 said...
Does anybody know why WA gets more shark attacks then east coast ?
No idea mate but I was wondering that myself and found this site, it's looks it could be a fairly interesting reasearch program.
http://whitetag.com.au/index.php?route=information/information&information_id=8Edit here's a story from Swellnet 2 about it
www.swellnet.com.au/news/3071-shark-tagging-in-the-southern-oceanLate last year the documentary Shark Harbour played on Australian television. The documentary makers followed a Sydney-based research team who were responding to a surge in local shark attacks. To gain information the researchers tagged and followed 25 Bull Sharks in Sydney Harbour. A common response to the show, both in the comments to the Shark Harbour website and also here on Swellnet, was surprise at the number of sharks swimming in popular waterways. Surprise because a common belief is that sharks and humans can't mix together. That any encounter leads to an attack.
Such a view fits with the popular understanding of sharks as irrational animals; mindless killing machines with behaviour that's impossible to predict. It's ironic then that this superficial understanding of sharks manifests itself as irrational behaviour in humans. Little wonder so many viewers of Shark Harbour were surprised - sharks and humans had been safely co-existing for a long time without any of us being aware of it!
The study of sharks and their behaviour is a burgeoning field. Relatively little is known yet there is a lot to be gained from a more accurate understanding of their behaviour. Recently a research team set sail from Port Lincoln, South Australia, with the goal of adding to the bank of knowledge. The team included scientists, Dr Rachel Robbins and Andrew Fox from the Fox Foundation, marine biologist Dr Will Robbins, and Russ Bradford from the CSIRO. Also aboard were a film team plus Kent Stannard of Whitetag, and lastly, Wayne Lynch and his son, Jarrah, both ambassadors of Kent's not-for-profit environmental program, Tag For Life. Wayne is the subject of an upcoming film and the research trip will be one component of it.
Wayne and Jarrah were more than just token surfers, however. Both were actively involved in the research and data collection which increased their own understanding of how shark science is performed. Wayne and Jarrah's involvement served a twin purpose: Of all ocean users surfers have one of the highest incidents of shark encounters, so having surfers involved in a research program helps the scientists while the benefits of gained knowledge ultimately flow back to us - surfers.
Much of the information we do know about sharks is gleaned from acoustic listening devices. On trips such as the one undertaken scientists apply tags to selected sharks. When the sharks move within range of listening stations they are detected and the data recorded. In Australia the listening devices form a network that identifies sharks and records their relevant information. The information helps shark scientists determine residency times and seasonal abundance patterns that form the basis for population modelling. Also, by plotting paths and frequencies scientists can ascertain types of shark behaviour.
Many different research agencies have placed listening devices around Australia and coordination of the information received is achieved through a national group based in Sydney known as AATAMS (Australian Animal Tracking and Monitoring System). AATAMS is also partnered with a global network that all use the same receivers to form a comprehensive network of tagged animals. Although researchers and agencies maintain their own smaller networks the information is shared co-operatively between agencies world wide.
In December 2011 a series of listening devices were deployed at four of the sites to be visited on this trip. One of the primary purposes of this trip was to revisit those sites and retrieve the data from the devices.
Taking advantage of calm weather the team's first stop was Dangerous Reef in Spencer Gulf. The aptly named Dangerous Reef is where most of the underwater sequences for Jaws were filmed, yet despite its infamy the team didn't see any sharks there. Curiously no research work had been done at Dangerous Reef for ten years yet it was one of the sites where a listening device was dropped in 2011. The scientists were keen to retrieve and download the data.
After the trip they found that a 5 metre white shark nicknamed Noah (scientists: clever folk, not always creative) had been detected. Noah was tagged in 2008 at North Neptune Island where he has been frequently detected since. The team found it interesting that he swam up the gulf to Dangerous Reef but what was far more interesting was that he was the only tagged white shark detected.
The simple explanation of science is that it is a search for answers, yet the process always begins by asking good questions. In this instance the question 'why was only one shark detected when more were expected?' will have to be suitably framed and ventured.
The next stop was Liguanea Island, south of Fishery Beach near Port Lincoln, to retrieve listening stations and to tag sharks. Four sharks were seen and tagged at Liguanea. The region had never previously been worked by researchers though it's thought to be on the 'shark highway' leading up the west coast of South Australia. For this reason Liguanea has become very important to researchers for the information it may hold. It is also very near to where the abalone diver Peter Clarkson disappeared last year.
After Liguanea the team moved south to the Neptune Islands. At North Neptune Island the team redeployed a CSIRO VR4 listening receiver. The VR4 is a more advanced unit than the other listening devices retrieved on the trip. It communicates directly via satellite to tell researchers when a tagged shark is present. This device was first deployed at North Neptune Island in 2008 as part of a joint project between CSIRO and the Western Australian Department of Fisheries and was the first of its type. It is similar to the models currently in use off Perth's metropolitan beaches (and which detected a five metre shark off Cottesloe last week).
Compatibility between tags and listening devices is essential due to the migration of sharks. The tags put in sharks in South Australia can be detected by the receivers in Western Australia, and in fact they have been many times.
At North Neptune the team saw two sharks and tagged one. At South Neptune Island they attempted to retrieve acoustic listening stations but the their run of good weather was over and they had to abandon their plans in the face of an increasing south-west swell and strong southwest winds. The team were forced to find shelter in the lee side of the island. Still, they saw two sharks and again tagged one.
From South Neptune Island the team motored back to the shelter of Port Lincoln with the majority of their tasks completed. A successful mission, although quite what they've achieved isn't yet known. For now it is up to the scientists to assess and analyse the information they've retrieved - to crunch the data, so to speak - before their findings can be considered another deposit in the growing bank of shark knowledge.
stuk
> 9 months ago, 14 Jul 2012
