DPV'S and Shark attacks?

[DVR]

Watching a program on Sky at the weekend "Worlds deadliest sea creatures" I think. A diver using a DPV was attacked by a great white. Could the electronic signal/pulse from a DPV be mistaken for that of an injured fish by a shark? just a question that crossed my mind and I know someone on here will have the answer....or if not they'l make one up.

Regards, John

[Lou]

This doesn't provide the answer but it does tell you alot about the electrical field sensitivity of sharks and especially the GWS. Quite, quite amazing.

http://www.elasmo-research.org/educa...oreception.htm

In 1998, graduate student Steve Kaijura demonstrated that newborn Bonnethead Sharks (Sphyrna tiburo) can detect electric fields less than 1 nanovolt per square centimetre. This is equivalent to the electric field of a flashlight battery connected to electrodes some 10,000 miles (16,000 kilometres) apart in the ocean. Such incredible electrical sensitivity is over five million times greater than anything you or I could feel and is by far the most acute in the Animal Kingdom.

The 72-hour captivity of a 7.5-foot (2.3-metre), 300-pound (136-kilogram) female White Shark at San Francisco's Steinhart Aquarium during August 1980 provided an unexpected opportunity to measure the electrosensitivity of this species. Dubbed 'Sandy', the juvenile Great White was displayed in Steinhart's torus-shaped 'fish roundabout', becoming an instant media celebrity and drawing some 40,000 visitors to the Aquarium over a three-and-a-half-day period. By the fourth day of her captivity, Aquarium director John McCosker noticed that Sandy continually collided with a particular five-degree arc of the tank. No visual, sonic, or vibratory cues were discernible at that particular segment of the roundabout. So McCosker and his co-workers suspected that a weak electrical field at that location might be causing her to bang her head against the tank wall. A silver-chloride half cell was used to detect a small electric potential difference between two of the tank's windows measuring 0.000125 volts -- an amount so tiny that none of the other sharks in the roundabout seemed to notice.

Just how fantastic is that?

[Little Pete]

Really interesting link there Lou thanks.

Now the question is whether you could get away on a proper boy racer modded up Gavin with a banging sound system (black, powered from an umbilical battery) and some nice neon lighting around the prop

[Bob Cooper]

A buddy of mine regularly does deep dives in the Pacific North West with scooters. I remember him telling me that a big problem for them on long dives is sharks! especially at deco. It is standard procedure for them to switch off lights and not use their scooters when sharks are about!

Bob

[DVR]

Cheers for that Lou,fascinating report. The reason I asked was the shark had passed the diver while he was stopped, but then returned and attacked while he was underway with the DPV, I know they sense minute voltage patterns that are different between healthy and dying/distressed fish and wondered if the DPV gave of the same type of signals as a distressed fish. I'm sure there will have been some research into this at some time.


John

[DVR]

Originally Posted by Bob Cooper

A buddy of mine regularly does deep dives in the Pacific North West with scooters. I remember him telling me that a big problem for them on long dives is sharks! especially at deco. It is standard procedure for them to switch off lights and not use their scooters when sharks are about!

Bob

Thats me not using a scooter then . I know there is a low voltage shark deterent that has been developed, I did'nt read any reports on how good or bad it was though.

John

[Mark Chase]

So if i slash Bob to bits and nick his Gavin in Stony cove, do you reckon Id get away with saying the perch attacked him?

PS anybody got Bobs sig as I have a will bequethig his scooter to me that needs signing.

ATB

Mark Chase