Mullas Shark - 20/6/12

Yeah, lucky guy Credit to his mate, for doing what he did.

Years ago any real perceived threat was, say October to December with the migrations. Things are changing for sure.. I'm all for conservation but FFS – at what point do they take action based upon statistics.. Some of the 'do-gooders' say there's more people in the water nowadays etc… Give me a break! At this time of year it's usually the same crew in the water that have been going for years.. Anyway, thankfully the guy gets to have dinner with his loved ones this evening, unlike many other unfortunate people recently.

And there I was looking forward to some Pinnas action between the showers later.. Makes you think...

I dont think putting a smokey in a couple is going to harm the species too much I wouldnt think, there is more than we think, I think

I don't want to be sitting next to someone in the line up attracting sharks with there shark shield, and they are proven to work.

Proven by whom and proven on what species? Also according to shark shield the whole initial attraction idea is a myth.. Lots of inconsistencies and rumours. That is why I would like a very reputable independent review conducted on a range of species over a very large sample size to clear up the myths and rumours.

not sure anymore , some time between 95 and 97 was still a poley

Would it leach for that long? I know they did the same to one at Cott as well, I think 01 or 02 from memory.

did that come out wrong?


brian sierakowski's ski got hit a few years off cott if i remember right too - you'd think the size of the things would put a 3m white off, but they are definitely hungry
makes me feel suss about my quick paddle in teh lago at leighton on dark last night...
and the mullaz guy was lucky it wasn't the 5m one that hit the commercial fishermans pot off warnbro! ther'd be no ski left!!!

LOL! Good pickup I guess I need to proof read for more than spelling and grammar before posting.. Rain showers

people need to stop cage diving and feeding them so they are scared of us on our boats and jetskis n surfboards instead of seeing us as a food source

Here is a pic for those that don't read the general forum or are to lazy to click on the links.



Myself and a friend were called in from a downwind SUP paddle last year at Mullaloo, we never saw a thing but apparently the chopper spotted a white approx 3 metres long fairly close to us.

Think we are winning

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."

Guys, the northerly humpback migration is well under way. At horrocks, 500ks north of Perth I'm seeing 3 or 4 whale groups a day passing by without trying at all to spot them. Some quite close to the coast.
The big sharks are following them looking for a feed I think.
I think in poor light conditions like at dawn this morning, the big sharks will have a crack at something to see if it is a feed or not.

I'm no expert at all, but I think now, and in spring when the whales are heading back to southern ocean we are at more risk, particularly in poor light conditions.

Won't stop me getting out there, but dawn and dusk, I'm heading back to the beach.

Dave

Could it have been a dolphin?
They did say there were a few in the water.

"Dolphins would chase the porpoises and ram their bodies with such force that they would be thrown into the air. This would cause a massive twisting injury within the porpoise's body, ripping blubber and muscle from its bones. Once the porpoise was dead, the dolphins would immediately lose interest and swim away.

Post-mortems on the carcasses revealed the true extent and ferocity of these attacks. Broken ribs, torn tissue, bruised organs, punctured lungs and smashed skulls and vertebrae were often the results of the dolphins' brutal and fatal beatings."