Dot Earth Blog: Chumming Around With Great White Sharks

One of my Pace University communication students, Martin Totlandt, spent much of the summer in South Africa and filed this ?Your Dot? dispatch about the controversy over the process of chumming ? luring sharks with a fishy, bloody brew spooned overboard ? something done both for science and for adventure tourism cage diving operations. The video above was shot by Totland of a shark encounter in June (the camera was on a pole). Here is his post:

As the finny, toothsome vortex that is the Discovery Channel?s annual??Shark Week? swirls this week, I?ve been thinking back on my summer in South Africa. In June and July I was in the town of Mossel Bay as an intern at the Fiona Ayerst Underwater Photography agency.??We spent our days going on various photographic excursions, editing photos and learning about life as freelance photographers.

While I was there, there was heated debate around the practice of ?shark chumming,? and whether or not it increases the risk of attacks on humans. As it turned out, I got to see?the process up close in the context of scientific research on great white sharks.

Fair regularly, we accompanied marine scientists from Oceans Research, an organization on the same campus as the photography program, on their boat trips. The scientists there study great white sharks and other elasmobranchs, tracking their movements via satellite and sonar tags, among other things.

To get close enough to sharks to be able to attach such tags to the dorsal fin, the scientists use the chumming process, which consists of dumping a mixture of water, fish oil, and mashed parts of sardines in the water.

When the sharks start circling the boat, a line with a float and a few tuna heads attached to the end is tossed out. This leaves the tuna floating right below the surface. When sharks go for the bait, scientists have a brief chance to attach acoustic tags.

This practice has gotten a lot of public criticism in South Africa. Opponents argue that sharks will, after enough exposure, learn to associate human presence with the possibility of food, which can potentially increase the risk of shark attacks.

In late April, a great white shark killed David Lilienfeld, 20, a South African body-boarding champion. In the wake of the accident some people blamed marine researchers and chumming for attracting great white sharks.

Obviously this is a contentious issue, especially in a place like Mossel Bay. Surfers occupy the beach virtually every day while scientists go about their business on their vessels, sometimes just a few hundred yards out from the beach.

There are, however, people on the other side of this issue, as there always are. They argue that it is highly unlikely that great whites will associate human presence with food since there is a huge difference (to sharks) between the sight and smell of a research vessel floating on the surface, and a human body being in the water.

A lot of the chumming that goes on in South African waters is due to the cage diving industry, where adventure-seekers are taken out in shark-infested waters to view these magnificent and imposing creatures up close. The spectators climb into steel cages attached to the side of a boat, wearing wet suits and masks, while the boat crew chums for sharks. I have done this myself and the sight is spectacular, to say the least.

The cage diving operators are not always quick enough to get the bait line out of the shark?s jaws. Although this means that the shark gets a mouthful of food, it is uncertain how often this actually happens. In other words, it?s an open question whether this conditions sharks to associate human presence with food.

According to a 2006 paper co-authored by Ryan Johnson, the co-owner of Oceans Research and a researcher focused on great white sharks, conditioning ?will only arise if [cage diving] operators intentionally and willfully contravene current permit regulations prohibiting intentional feeding of sharks.?

In fact, according to Johnson?s research, negative conditioning can occur if operators adhere to the feeding and chumming regulations. In short, if you?re good enough at pulling away the bait line so that the shark doesn?t get to eat, they could eventually learn to associate the presence of boats with no food rewards.

When I accompanied the researchers from Johnson?s organization on their vessels, I saw the effectiveness of chumming. Generally it takes no longer than 20 to 30 minutes to attract at least one great white, but normally you?ll see four to six sharks. One day we attracted 11 different sharks to the vessel.

It?s clear there?s more research to be done, but also seems fairly evident that proper procedures can lure sharks, when necessary, without raising risks to surfers and others eager to enjoy ocean waters in regions also frequented by this remarkable predator.

Source: http://feeds.nytimes.com/click.phdo?i=57278c95893ca6277fd51c9dce6ae6aa

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