Monday, October 5, 2009

Shark Feeding – The Debate Continues

Another blog post making the rounds on the Internet discusses "shark feeding" - once again.

While the conversation about chumming and habituating sharks is a perennial favourite, clearly more study needs to be done with operators enabling research at sites where sharks, people, and chumming occur.

Shane Pinder Blog

This is a continuation of the topic of shark feeding dives started in an earlier post.

Scuba Diving Forum posted a comment to that post that included a link to a very interesting article on the Shark Foundation site about a study on the impact on white shark cage diving.

The study concluded that chumming for white sharks does not condition or habituate them because the sharks don’t receive any food in the chumming process.

I wonder though if the research on white shark cage diving applies to the type of shark feeding done in the Bahamas and other parts of the Caribbean.

The conclusion that white shark cage diving does not result in the conditioning of white sharks to associate humans with food seems to hinge on the fact that white sharks are not fed during cage dives. The water is chummed with blood to attract them and the food on bait line is pulled away from them so that they never actually get a reward.

This is not what happens on shark dives in The Bahamas. The sharks do receive a reward (food). The article does refer to conditioning of three shark species in captivity -

“Conditioning has been demonstrated in a captive situation in the lemon shark, Negaprion brevirostris (Clark 1959, Wright & Jackson 1964), nurse shark, Ginglymostoma cirratum (Aronson et al. 1967) and the bull shark, Carcharhinus leucas (Wright & Jackson 1964). ”

These species are all present in Bahamian waters.

The article also discusses the demonstrated learning ability of Tiger sharks (also present in Bahamian waters) - “The learning ability of sharks is also demonstrated under natural conditions. For two weeks a year in June off the shallows of Hawaii, tiger sharks (Galeocerdo cuvier) congregate to feed on young albatross that take land on the waters surface whilst learning to fly (Martin 2003). Although the sharks initially have very little success in preying on the chicks, within 3-5 days they learn the technique needed to successfully capture the young birds and, on missing a prey item, to swim a short distance upwind to where the panicked bird will land (Martin 2003).”

The question is still whether or not the type of shark dives which involve sharks obtaining a reward (food) condition sharks to associate humans with food.

If these dives do create conditioning, does it follow that sharks are then more likely to attack humans in areas where they have been conditioned to associate humans with food?

From personal experience, I know that there are dives sites close to shark feeding sites where you can expect to see sharks even though no feeding is going on. In my experience, while the sharks at these sites have not been aggressive, they certainly hang around during the entire dive. They don’t appear to be bothered by such close contact to humans.

On dive sites that are not close to shark feeding sites, it is unusual to see any sharks. If you do happen to see a shark, it is usually only a glimpse of it as it cruising by in the distance. It doesn’t hang around.

Have a look at the article posted by Scuba Diving Forum about the study done by the Shark Foundation. What are your thoughts?

  • Does this study help to confirm that shark dives in which sharks get food do not condition sharks to associate food with humans?
  • Do you think that shark dives that result in sharks being fed condition sharks to associate food with humans?
  • If sharks are conditioned by these types of dives to associate food with humans, does that make it more likely that shark attacks will occur?


Johann said...

Hi all,

as a response to these questions, we (a 4 scientists team)have just completed a scientific study on the response of a reef shark (sicklefin lemon shark, N. acutidens) to daily long term shark-feeding dive operations. This study will be submitted soon to a scientific journal.
We followed the daily presence of lemon sharks at a feeding diving site for 4 years, analysing changing in behaviour (i.e. fidelity, reproduction, aggressivity...). Some sharks (residents) showed a degree of increase in residency but shift in shark population structure does still occur every year at the mating period with resident desappearing and new sharks coming. This suggest that shark-feeding does attract sharks but does not completely condition them.
I am actually analysing some gentic data on this population that will help understand if this practice does affect the biology of a shark population.

Be patient, the paper will come soon.


Shark Diver said...

Fantastic guys, let us know when it comes out and we'll post your results.