PercyPenguin said...
Guys - can't do the link thing; sorry. Look up Huveneers et al 2012 - Worksafe SA... Gives you the independent testing you want. P9 gives a great summary. It appears that the Shark Shield is extremely effective on a towed, moving/paddling (by extrapolation) target than on a stationary one... So... If you are paddling (fast), or kiting, you're probably ok. If you're sitting stationary in the lineup, you probably don't wanna be you... And... I don't wanna be sitting next to you... I wanna be up in the carpark towelling off and not looking...
From:
ABC Adelaide 20 June, 2012 12:01PM ACST
"SA researchers trial effectiveness of electronic shark deterrent devices on Great Whites"
Researchers from the Flinders University and SARDI have undertaken experiments at Neptune Island to discover what responses Great White sharks have to electronic shark shields.
The researchers used two methods and two separate locations to collect data, with a seal decoy towed behind a boat off the coast of South Africa, and a tuna bait and burley used near Neptune Island in South Australia.
Both tests were undertaken with the commonly used Shark shield Freedom 7 device, a submersible unit used strapped to the ankle of the user, with a 2.2m long braided antenna that emits an electronic pulse.
The pulse is said to create an elliptical field that is believed to agitate the Ampullae of Lornenzini electro-receptors on a shark's nose, making it unpleasant for the shark to remain in the area.
The receptors on a shark can help the animal locate food sources, in particular injured animals with erratic electromagnetic pulses.
The research and results
Researcher Dr Charlie Huveneers from the South Australian Research and Development Institute (SARDI) and the Flinders University was quick to point out the experiments were not used undertaken to rate the protectiveness of the device and should not be used to draw parallels for human and shark interactions.
"What we were aiming to do was to look [at] how the shark shield is affecting the behaviour of the White sharks.
"We can't apply our findings to specifically what would happen in the case of an interaction between a human and a shark, but what we can do is learn from what we have observed in understanding how sharks might behave to the shark shields."
Researcher found results varied from shark to shark, and even between the two testing methods.
When the seal decoy was towed behind a boat in South African waters for a total of 189 trials near Seal Island, when the shield was not turned on, 16 breaches and 27 surface interactions were witnessed.
When the unit was turned on, sharks were seen to visibly abort attack charges, with not one surface breaches observed.
Alternatively sharks were observed for 116 static bait trials near Neptune Island in South Australia, were not seen to be uniformly affected by the activation of the shield, with several sharks swimming within two metres of the activated device, and baits were also taken.
The South Australian Studies
Three separate trips were made to Neptune Island to gain data on the Great White Shark's interactions with the devices.
Neptune Island is home to a large seal colony, a ready food supply to the Great White, with three tourism operators running cage dive experiences from the location.
Tuna baits were placed 50 centimetres below a surface float, with the electronic device attached to another surface float 150cm from the bait.
The device was attached to a dropline at 150cm below the surface, with the antenna depth varying with the local currents from between 100 to 300cm below the bait.
Of the 116 trials completed, 49 were conducted with the units turned off and 67 with the units activated.
A total of 314 approaches and 527 interactions with 18 different sharks were identified.
Of the total approaches and interactions, 132 approaches and 179 interactions were made by sharks that were not identified.
Approaches from the individual sharks varied, with one individual approaching the bait 40 times and recording 67 interactions.
Out of the three trips, four sharks were observed only when the device was turned on, with one shark observed only when the device was turned off.
"In South Australia we found that the shark shield didn't impact the proportion of bait being consumed," Dr Huveneers said.
Dr Huveneers said they observed that sharks generally kept a little further away from the baits when the shields were activated, but were also seen within 50 cm of an activated unit.
"They are physically capable of being in close proximity to an operational shark shield."
The number of interactions within two metres of the bait was noted to decrease when the devices were activated.
"Do electronic shark deterrents work?
Dr Huveneers believed shark devices did change the way a shark interacted with an attractive lure, but the results could not be correlated to what may happen in a shark/human interaction.
"We didn't check the shark shields with humans, or in a situation like that, but what we did get is a better understanding of how the shark shield did affect the behaviour of sharks in the two situations that we tested."
Mr Huveneers observed that the Great Whites, on average, took twice as long to take the static bait when the device was turned on, suggesting the activation of the unit did cause hesitation for some of the animals.
The report concluded that the deterrent tested had an effect on shark behaviour "but did not deter or repel them in all situations nor did it repel all individual sharks."
SARDI hoped to conduct further research on electronic devices being used to repel shark interaction, trying different variables than the original tests, and also observing reactions from different species of sharks.
Martin Grace, general manager of Shark Shield was encouraged by the results of the report, particularly the doubling of response time to sharks taking baits at Neptune Island when the devices were activated.
He acknowledged that even thought the testing was done in what he described as a 'non-standard user environment' the devices increased the take time of a static bait on average from 122 seconds to 244 seconds.
"Water based activities in the presence of sharks are inherently dangerous, therefore we recommend that if a shark is sighted the user gets to safety rather than continuing with their activity.
"It should not be used to swim with sharks."
The project was funded by SafeWork SA, Neiser Foundation, Winifred Violet Charitable Trust, Save Our Seas Foundation, Flinders University, the University of Adelaide and Marine Innovation South Australia."
Credit to his mate, for doing what he did.
