Thursday, February 05, 2009

Feeding Sharks - a Battlefield of Opinions. Finally a Voice of Reason and Authority...

Dr. Samuel Gruber in his element
Photograph: Wolfgang Leander

... the voice of "Doc", Dr. Samuel Gruber, one of the most experienced shark biologists of our time.

Very kindly, Doc gave me the permission to quote a letter he wrote to a TV producer who wanted an expert opinion on the subject of diving with, and feeding, 'dangerous' sharks; specifically, how it does affect or else alter shark behavior, and also whether Dr. Gruber would consider cage-free shark diving a "hazardous" activity.


Hi ................. :

I am a proponent of shark diving. While it does affect a few
sharks, when compared to the approximately 100 million killed annually for fin and flesh the minimal impact of this human activity pales in comparison.

I feel that shark dives produce several very beneficial outcomes for humans and sharks. First exposing divers to sharks, safely and professionally - and in a beautiful environment will inevitably turn fear into fascination. Quickly these people become ambassadors for shark conservation. Further it produces jobs and income for areas and folks that need the work - especially in an economy such as the Bahamian one. Tourism in the Bahamas is the country's life blood, and sharks are a draw!!

As for hazard - tens of thousands of divers worldwide have safely enjoyed professional shark encounters ever since they were established in the Bahamas nearly 40 years ago. It is true that some people have been injured and there was even one fatality, but compared to other water sports this is a pittance.

Nearly a decade ago the World Health Organization estimated that over 400,000 people drowned in year 2000 making this the second leading cause of unintentional death after highway accidents. So shark dives turn out to be a very SAFE form of water activity when conducted in a professional way.

Dr. Samuel Gruber using his "magic wand" to lead a lemon shark, Bahamas *)
Photograph: Matthew D. Potenski

What I have written is controversial. Animal lovers think that humans have no right to interfere with non-human creatures. This is their opinion, not mine. Biologists always say "don't feed the animals." But I have been feeding sharks at my field station for over 20 years, and have observed their behavior carefully (my degree is in marine animal behavior and sensory physiology). I know for a fact that our shark encounters do not greatly affect the Caribbean reef sharks we feed.

- They do not become habituated to humans such that they completely lose their natural fear.

- They do not begin to consider us as food.

- They are very focused on what we do and learn almost instantly what the feeding situation means.

- They do not depend on us for food but hunt normally and supplement this ordinary behavior with our feedings.

- New individuals join the colony all the time, learn what we do and do not pose a danger. These reef sharks leave the area during breeding season in August and go about their normal reproductive activities. They return about three months later.

My favorite dive site is Tiger Beach in the Bahamas, and I would be very pleased to take you there (on your nickel) to show you amazing sights that should make you a believer. We are planning a trip later in the month.

"Doc" freediving at Tiger Beach, November 2008
Photograph: Wolfgang Leander

Remember many sharks are headed toward extinction which will have very deleterious effects on the Ocean ecosystem. We call sharks the "Lords of Time," having survived multiple extinction episodes for half a billion years. We really need sharks more than they need us! An ocean free of sharks will be a sick ocean. This is the story that shark dives engender - not the tired old monster jaws images.


Thank you very much, Doc - that's certainly good enough for me!! :-)

Doc's "magic wand" is a bi-metallic rod that stimulates the sharks' ampullary system so that they think the end of the pole is a living prey.


the One called "Bitey".... said...

"[...] the approximately 100 million killed annually [...]"

I just finished reading this:
- which prompts me to ask the honorable and venerable Dr. Gruber - where do you get your number? I have great respect and admiration for him, so I'm very interested to know.

Felix Leander said...

Hi Bitey - the estimates in the the article in the link you mention are from reports published 3 years ago. The number since then has more then likely increased. I also think the exact number will always be a debate and in the end is not really the issue - the point is that too many sharks are being killed

Felix Leander said...

And Luke Tipple worked with Discovery Shark Week on the Myth Buster segment - enough said with that...

shark8matt said...

I have worked with Doc for about 10 years (that's my photo of him leading the lemon). I also worked with Luke Tipple briefly in Honduras. Luke is young and while his zeal is admirable, there are some flaws in his journal. The numbers bandied about in the articles mentioned are reports from fisheries. These reports are notorious for under-reporting actual catch. Legal fishing also only accounts for a portion of sharks taken and many times do not account for bycatch and the biggest foe to shark populations - illegal fishing. The statistics involved showed the actual number to be somewhere between 10 and 73 million sharks - that's a wide range and indicates a lot of error inherent in the methodology. I believe, as most shark biologists do, that the true number is close to 100 million a year and that has widely been accepted. Shark fisheries have been expanding and I think as far as we can try to estimate a problem with so many unknown variables, Doc's accepted estimate is much more accurate than the literature mentioned in Luke's article. I do commend Luke for being brave and trying to refute that number - after all that is what science is all about. A deeper look at the actual literature and you will see it is mostly statistics that i believe falls far from the mark of describing actual events in the outside world.
cheers.... - MDP