Some scientists worry that feeding the whale sharks from 6 a.m. to noon 364 days of the year might be disruptive. The natural behavior of a whale shark is to travel long distances.

Whale sharks can migrate 12,800 kilometers (8,000 miles) in a ­three-year period. In Oslob, most of the whale sharks move on after a few days or weeks. But about 4 percent become year-round residents. Scientists don’t know why some stay and others go. They also don’t know why the whale sharks in the area are all young males. Mature males aren’t around, and females don’t seem to be present either. Scientists are concerned that this may be a pattern created by feeding the whale sharks.

Researchers worry that the sharks may start to depend upon people for food and become less wary of people and boats. Whale sharks naturally eat a variety of food, but the tour guides off Oslob only supply the whale sharks with massive amounts of shrimps.

A larger problem might be that the sharks associate boats with food. About half of the whale sharks studied in Oslob have cuts on their bodies caused by propellers. The tourist canoes at Oslob don't have propellers. They are powered by paddles. They don't hurt the whale sharks. But the sharks may be drawn to boats with propellers hoping for a tasty handout. They can get hurt instead.

Tourists are told not to wear sunblock in the water, as it contains a chemical toxic to wildlife. They are also told not to touch or ride the whale sharks, but many swimmers break the rules. What does that mean for the whale sharks? Is the physical interaction with people a problem? No one is sure yet.