The risk of a shark attack when diving inshore waters of Western Australia

[Ste Wart]

In fact I was barred from a wreck dive while doing my advanced open water course because I insisted on wearing a Sharkshield in an area not far from a recent fatal attack on a snorkeller. The instructor cited concerns about the risk of entanglement while diving the wreck as the reason for barring me from the dive. I had offered to take the Sharkshield off prior to entering the wreck. I've subsequently done the dive on several occasions with the Sharkshield on and never had a the slightest problem. I find it ironic the instructor was absorbed with the risk of entanglement which while completely ignoring the more significant risk of shark attack. I attribute that mostly to a failure in his training as a diver.

Putting faith in a placebo is also a failure as a diver.

Also the antenna is absolutely an entanglement hazard. Your instructor was in the right. You do not enter a wreck with a length of cord trailing from your fin, period!

1. A white pointer can swim at speeds of up to 56 km/hr. Great white shark - Wikipedia, the free encyclopedia I'd estimate a fast swim in scuba gear would be 60 m in a minute which is 3.6 km/hr. That means a white pointer can swim about 16 times as fast as a human in a short burst. I'd estimate a quick runner could cover 50 m in 7 seconds or run about 25 km/hr. Therefore an equivalent land speed for the mythical creature is 25x16=400 km/hr.

The Sharkshield only has an effective radius of 3-5 metres. Now compare that to a White Pointer charging at full tilt, do you honestly believe that shark is going to turn around when it hits the Sharkshield?
We used to sell these at Cape Dive, and to be honest they flew off the shelf. Then one day while heading out to the Swan our skipper (part-time) spotted a customer putting one on just before a dive. He inquired about the radius and the customer stated around 5m
He then said 'oh do you realise the Mako can attack at speeds of up to 20m/s?". The customer took off the sharkshield and went for a dive.

 

[Wingy]

Agreed Foxtrot..I was out the back of Rotto on Sunday for 9 hours and didnt see a single fin break the surface - ok, saw a humpback but as for this infestation of man eating sharks the OP keeps harping on about.....It just is nowhere near any of this hyped up froth.
"Why should we listen to you"

Skipper of the boat I was on made a wise remark - of course there were no daily sightings of sharks along perth beaches in previous decades....we didnt have a helicopter in the air looking for them then!.

Like Foxtrot, still alive and diving in W.A...well, except for sunday, swell out the back of Rotto made it impossible to stay out let alone dive.

 

[Foxfish]

Also the antenna is absolutely an entanglement hazard. Your instructor was in the right. You do not enter a wreck with a length of cord trailing from your fin, period!

I have used the Sharkshield on most dives both freediving and scuba diving over the past nine years and have never had an entanglement, including while diving on wrecks and will continue to do so.

 

[Ste Wart]

I have used the Sharkshield on most dives both freediving and scuba diving over the past nine years and have never had an entanglement, including while diving on wrecks and will continue to do so.

Which is fine and your choice. I'd wager though you are just swimming into these wrecks and not laying line?

 

[Foxfish]

Which is fine and your choice. I'd wager though you are just swimming into these wrecks and not laying line?

I have not used it with a line on a penetration dive. As previously stated, if I thought it was likely to cause problems I'd take it off inside the wreck.

On the question of the effectiveness of the Sharkshield, there are a lot of people who testify that it has been effective and in some cases saved their life.

Our Customers Are Saying

I've had my own experiences and was glad to be wearing one on those occasions.

 

[Ste Wart]

I have not used it with a line on a penetration dive. As previously stated, if I thought it was likely to cause problems I'd take it off inside the wreck.

Then you are not doing wreck penetration.

On the question of the effectiveness of the Sharkshield, there are a lot of people who testify that it has been effective and in some cases saved their life.

Our Customers Are Saying

I've had my own experiences and was glad to be wearing one on those occasions.

I'd imagine a lot of good reviews are on a manufacturers page

From the Page:
Shark Shield - Electronic Shark Deterrent - Proven Protection from Sharks

If faced with a five metre white pointer in the waters off Western Australia, not many people would swim toward it to get a closer look but that's exactly what Paul Hosie did over the weekend.
Mr Hosie says he has seen plenty of large marine life underwater including whale sharks, manta rays and seals but this was his first encounter with the ocean's top predator.
Paul Hosie was diving at the HMAS Swan wreck site just off the coast of Dunsborough on Sunday when he noticed a big black shape go past him just 10 metres away.
"When I looked at it there was no doubt what it was; it was dark above with white below, just the enormous bulk of it and a massive tail fin."
The unmistakable sight of a great white shark would leave most people swimming in the opposite direction but Mr Hosie was fascinated by the sight and wanted to get closer.
"After about five minutes of observing it, I decided that I wanted a closer look. A lot of people would say that was a foolhardy stupid thing to do but I had a shark shield and I know the behaviour of these things.
"People are taken from the surface, that's how these things feed and attack not at depth, not normally."
Mr Hosie is an ex-Navy member who has been recreational diving for 18 years and was diving with his fiancee Christie at the time. He says he has seen many sharks over the years but this was by far the largest shark he has seen while diving.
Mr Hosie and his partner were wearing an 'electronic shark deterrent' at the time, which is a device that straps around the ankles with an antenna hanging below the diver which emits an electric field that induces spasms in a shark's snout.
However, the effectiveness of the device was about to be tested by Mr Hosie as he swam down away from the wreck and down to the ocean floor, the same level as the shark.
"It actually did take an interest in me because something had moved into its space and it swam straight towards me from about 20-30 metres away.
"At about 10 metres away when it was still heading straight towards me and I established eye contact, that's when I thought, 'maybe this wasn't such good idea'.
"But I had faith in my shark shield otherwise I wouldn't have been wearing it and about 5 to 7 metres away, it turned away from me."
Mr Housie has been wearing the electronic shark deterrent since a fellow diver was killed by a great white in 2008 at Port Kennedy, a location that Mr Hosie frequently dived.
"I don't go diving to put my life at risk; I dive to enjoy the experience so from then on I've worn a shark shield all the time."

I've dived this wreck around 200 times, the only shark on the wreck is a Wobbegong.

Firstly viz rarely gets to 20 metres and 30 metres is unheard of, the dark shape could have been a bull ray. So for a start this story sounds suspicious. Then you see a shark and decide to investigate? Hmm I doubt it. You would head up the to the crow's which is the shallowest part of the wreck (9m iirc) and still provides some protection.
Also he left his fiance to check out if he saw a shark? What about her? Sounds like a planted story to me.

 

[Foxfish]

Firstly viz rarely gets to 20 metres and 30 metres is unheard of, the dark shape could have been a bull ray. So for a start this story sounds suspicious. Then you see a shark and decide to investigate? Hmm I doubt it. You would head up the to the crow's which is the shallowest part of the wreck (9m iirc) and still provides some protection.
Also he left his fiance to check out if he saw a shark? What about her? Sounds like a planted story to me.

I've heard enough to be satisfied the Sharksield provides adequate protection to justify it's use. If there was a big white pointer in the water I'd be heading back to the boat.

 

[Ste Wart]

I've heard enough to be satisfied the Sharksield provides adequate protection to justify it's use. If their was a big white pointer in the water I'd be heading back to the boat.

Shark shields failed some tests: researchers - ABC News (Australian Broadcasting Corporation)

No difference

Researcher Charlie Huveneers wrote up the results.
"In South Australia with the static bait, we did not find any differences in the proportion of bait being consumed by white sharks whether the shield was turned on or off," he said.

waundersea.com - View topic - Shark Shield not effective against hungry white tips

According to this forum the manufacturer doesn't know if it's effective against all sharks.

As I said before, Placebo. You can choose what you wish to believe though

 

[Foxfish]

Shark shields failed some tests: researchers - ABC News (Australian Broadcasting Corporation)
waundersea.com - View topic - Shark Shield not effective against hungry white tips
According to this forum the manufacturer doesn't know if it's effective against all sharks.
As I said before, Placebo. You can choose what you wish to believe though

I'm very aware of the discussions on the topic.

 

[gcarter]

Interesting perspective on the topic, but the number of deaths alone don't give the whole picture. You would need to also assess the hours of exposure to a risk and determine a probability of something happening taking this into consideration.

Another way to consider the risk would be the following mind game. Imagine you are in the middle of a fenced circular bare paddock. It is getting dark and you can only see for a distance of 20 m. The paddock is 4 km in diameter. There is a wild beast roaming the area that can move at 400 km/hr in a short burst (1). Even in the dark the animal can identify your presence from 1.5 km (3) and can sense your movements and direction of travel from 250 m. The animal is considered very aggressive towards humans and is known to cut them in half with a single powerful bite.

How safe would you feel in that situation? What would you consider to be the risk of a fatal attack in that situation?

1. A white pointer can swim at speeds of up to 56 km/hr. Great white shark - Wikipedia, the free encyclopedia I'd estimate a fast swim in scuba gear would be 60 m in a minute which is 3.6 km/hr. That means a white pointer can swim about 16 times as fast as a human in a short burst. I'd estimate a quick runner could cover 50 m in 7 seconds or run about 25 km/hr. Therefore an equivalent land speed for the mythical creature is 25x16=400 km/hr.



Great White Shark | Smithsonian Ocean Portal



Jaws: The natural history of sharks | Natural History Museum

When doing a risk analysis, one must determine whether the cost of any proposed mitigation strategy is warranted by the risk. You obviously disagree with the answer, but it is clear that your government, and (based on comments) most here, feel that the cost (not just dollar cost) of a cull is too high relative to the small risk avoided.