Jump to content

Shark shield effectiveness questioned at inquest


werewolf

Recommended Posts

Effectiveness of shark shields questioned at inquest

By Nance Haxton

http://www.abc.net.au/news/stories/2008/02/28/2175484.htm

Does a device designed to repel sharks actually work?

A South Australian coronial inquest into the death of 23-year-old Jarrod David Stehbens, who was killed in a shark attack on the Glenelg Tyre Reef two years ago, has raised questions about their effectiveness.

The inquest has heard that shark shields were available on the dive boat that took Mr Stehbens out to sea, but were not used because some university staff had concerns that they may actually attract sharks.

Justin Rowntree told the inquest that he was diving with his colleague, Mr Stehbens, when the attack happened.

He saw a great white shark grab Mr Stehbens's leg and drag him away.

The men's employer, the University of Adelaide, did issue shark shields to employees diving in the course of their research.

Other employees of the university have told the inquest that very few wanted to use them because of rumours that the shields attracted sharks, rather than deterred them.

Employees from the company that makes the shark shields have also been giving evidence at the inquest.

Sales manager Paul Lunn says there is no basis to rumours the device attracts sharks, rather than repelling them.

"It renders the shark pretty useless when they enter that particular zone; that wave form protective zone," he said.

"[They are] very, very effective.

"The larger the shark, the more aggressive the shark, the more developed is the ampullae of Lorenzini and the easier it is for this wave form to deter the shark."

Shark shields work by creating an electronic field around the swimmer which will repel sharks.

The company says that sharks sense electronic fields in their search for prey, and the pulse created by the shields overwhelms the shark's senses.

Mr Lunn says the shields do not work on some species, such as wobbegongs and carpet sharks, but these are less of a threat to humans.

He stands by their effectiveness on the bigger predators, such as great whites and tiger sharks.

"Dissipation of our particular wave form over a given distance will not attract the sharks in," Mr Lunn said.

"It is not the same wave form as that given off by the prey, or an injured animal, or whatever.

"There is no basis to that [rumour] whatsoever and we constantly have to argue or get into [a] debate about that, but on lots of experiments - we've actually tried to bring sharks in by having a unit set up overnight and it's never ever worked in the many, many years of the testing that we have done."

Whyalla-based commercial diver Tony Bramley runs a diving operation from the South Australian regional centre on the Spencer Gulf.

He says the shields have potentially saved his life on more than one occasion.

"I provide the shark shields for the divers to use, especially when they are working in open water environments," he said.

"I think they work very well.

"I've seen the effect on sharks, and I'll guarantee that they don't like the pulse of electricity that the device produces. But I can't guarantee that the shark itself can't override that dislike if it wants to."

Shark researcher Andrew Fox warns that shark shields should not be relied on too heavily.

Mr Fox - whose father, Rodney, was attacked by a shark and nearly died in 1963 at another Adelaide beach - says they should be treated like a seatbelt in a car.

"I guess that's the danger ... a lot of people think that it is a black and white answer. Whereas a lot of things about shark attack prevention are a lot of common sense things, like not swimming in areas where there [is] a lot of food or blood in the water [or] at certain times of the day in certain areas," he said.

"But that should also apply to any shark repellent [because] it's possibly that it's not 100 per cent effective with all sharks in all situations.

"But if it is going to help the chance of decreasing the chance of shark attack, then in that case, it gives more peace of mind and is a wise thing."

Well I tell you what, if I had coughed up big bucks for a shark shield, I would be getting pretty nervous that is was attracting noahs rather than repelling them!:blink:

cheers vvwolfB)

Link to comment
Share on other sites

well no matter what in my lifetime it may never happen but rest assured that if me and you went offshore in a kayak togther and i had my $770 sharkshield on me and you were 100m away dropping baits down and a 15ft tiger came up and nudged your yak 2klm offshore, I can bet you will be yelling at me to turn it on!

Link to comment
Share on other sites

I have read another article about the inquest and they reported that university staff didnt want to use the device because it was bulky and uncomfortable to use.

Ive seen docos when they were testing the system and sharks didnt seem to like it at all.

Link to comment
Share on other sites

but wait, there is more! This particular shark shield was so effective, the shark ate it!:woohoo:

Shark Shield device fails, becomes shark food

By Humphrey Cheung

Tuesday, March 04, 2008 13:58

Adelaide (Australia) – An anti-shark device became shark food after it failed spectacularly in the waters near South Africa. This shocking (ok maybe not so shocking) information came to light during an inquest held in South Australia over the death of a swimmer who was wearing the same device. The Shark Shield device promises to repel sharks with pulses of electromagnetic waves, but some people think it is high-tech snake oil.

Sold for 765 AUD, the Shark Shield consists of a battery and an electrode that you wear on your tank or body. The electrode puts out an invisible ‘shield’ of electromagnetic waves that supposedly cause muscle spasm in sharks that get within five to eight meters. Sharks have tiny pores in their nose area that detect EM fields and the inventor of the Shark Shield says the shark feels like it is listening to cranked up speakers.

Rod Hartley, director of Sea Change Technology and makers of the Shark Shield told the inquest panel that the device does not attract sharks. However, the company seems to be hedging their bets in their online FAQ by saying, “However, it must be remembered that all sharks are dangerous and unpredictable creatures, and therefore a 100% guarantee cannot be given. It is impossible to guarantee that all sharks will be deterred under all circumstances.â€Â

The Shark Shield failure in South Africa happened after researchers activated the device on a test raft that was carrying some bait. A 3.6 meter-long female shark then ate the device.

A quick look at several diving and surfing forums show that many people do wear the device and are quite happy with how it works. Other wearers says they haven't notice any changes in shark behavior and that the sharks initially seemed to be attracted to the swimmer.

The inquest is being run by South Australia’s Deputy State Coroner Tony Schapel. Mr. Schapel is investigating the death of Jarod Stehbens who presumably died by shark attack two years ago while wearing two Shark Shield devices. Stehbens’ body has never been found.

http://www.tgdaily.com/content/view/36320/113/

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...