What is effect of a strobe on a shark?

[Merphotog]

Greetings,

I've been asking about a question that I can not seem to get a good answer on.

In light of sharks ability to sense the bioelectromagnetic field of prey up to several centimeters away, what perception does a strobe firing and/or recharging have upon a shark and what kind of stimulation might it cause?

I have run across multiple stories where a shark is posturing and the strobes flash triggers an attack. But is there a connection with the "sensing" or is it more an issue of space invasion?
- In the mentioned cases the sharks are "posturing" which is said to be basic SharkSpeak saying "GO AWAY [or else] !!!".
- Photographers as a rule are traveling TO what they have in the viewfinder as opposed to Away from. A clear violation of the sharks "suggestion".

So does a strobe stimulate an attack in and of itself? Or is it the photographer "in your face" that's doing it?

 

[pafindr]

Do you mean like this?

YouTube - Tiger Shark Bite

 

[gcbryan]

There isn't an answer. I can tell you that I've had a strobe close to the eye of a 10 foot sixgill shark and it did nothing and this is a deep water shark that has no iris and therefore cannot regulate the amount of light coming in.

I try not to do this but I have. Others can tell you of doing this and it resulting in aggressive behavior. Maybe it depends on the shark but my guess is that it's more than that....the shark was already feeling aggressive.

 

[drbill]

There was a recent story of a diver firing a strobe (I think it was a strobe, maybe it was an HID light) in the direction of a great white shark off Catalina, causing it to take off in the opposite direction.

I carry my camera on all my dives since it is the best insurance that I will never actually see one (even though one swam by me a mere 30 ft away a few summers ago).

 

[Desert_Diver]

Its been some time ago and I have forgotten some of the details, but I remember a story by a National Geographic underwater photographer. He maintains that the high pitched noise made by his strobe as it recharged incited a shark attack on him and his dive buddy. It was in a place like Chuuk or Bikini (lots of WW II sunken ships).

 

[reeldive]

I've had one bull and several reefies turn and run when my stobe fired.

 

[gcbryan]

Some people up here that dive with scooters claim that they see more sharks than others due to the electromagnetic nature of their scooter motor. It's BS of course since the ability of a shark to sense those fields is limited to several inches (the purpose being to detect fish under the sand).

Most of these shark theories are just like that. Just something someone pulls out of their...well, you get the picture!

It's like the size reports of sharks. The biggest sharks reported are always first time shark viewers or from those divers who have an exaggerated story about everything they talk about.

 

[Jim Ernst]

There was A show put on Discovery Channel not to long ago, And it was hosted By Mike Degruy, Very famous Underwater Photographer/Cinematographer, And he showed the Video of himself Taking A picture of A Grey reef shark that was Posturing, The second he fired his strobe the shark attacked him and caused Major injury to his arm!!

Mike Stated that he should have know'n better, and not have fired his strobe, as he felt that was the cause of his attack!

 

[gcbryan]

There was A show put on Discovery Channel not to long ago, And it was hosted By Mike Degruy, Very famous Underwater Photographer/Cinematographer, And he showed the Video of himself Taking A picture of A Grey reef shark that was Posturing, The second he fired his strobe the shark attacked him and caused Major injury to his arm!!

Mike Stated that he should have know'n better, and not have fired his strobe, as he felt that was the cause of his attack!

The shark was already posturing right?

I have a hard time listening to that guy. He is enthusiastic which is good but everything is so wonderful, so fantastic....I'd like to see just one good dive show/film/video without all the hyperbole.

 

[Jim Ernst]

The shark was already posturing right?

I have a hard time listening to that guy. He is enthusiastic which is good but everything is so wonderful, so fantastic....I'd like to see just one good dive show/film/video without all the hyperbole.

Yes, The shark was already posturing, And as he said, he knew better!