In truth, large sharks tend to hunt large blubbery prey with a much higher ratio of flesh-to-bone than human beings. That is apparently why many test bites on a human result in no further attack. In the last decade, a tourist industry has evolved in parts of the world with access to coral reefs and natural shark populations. Hand-feeding excursions allow divers, lead by more experienced professionals to encounter sharks in the wild without a high likelihood of attack. Typically, divers descend to the ocean floor where they assemble into a tight group that de-emphasizes their appearance as meal-sized organisms and merges them (from the sharks' point-of-view into a single larger organism, too large to eat. But other procedures involve much smaller groups of two or three divers to hand feed sharks, relying only on the fact that most sharks tend not to perceive humans as potential prey, unless we exhibit specific characteristics or linger at the surface in their habitat (Perrine, 1995).

On one hand, these industries illustrate how out of proportion our fears of shark attack are in comparison to the reality. On the other hand, these excursions probably increase the incidence of attacks on swimmers and surfers. While sharks do not actively hunt humans as prey, they are very susceptible to learned associations. Shark attacks have been documented to increase in areas where hand-feeding tours operate, simply because sharks in the area learn to associate the sound of boats and human activity with feeding. Once drawn to human swimmers, they may very well initiate test bites on anything in their vicinity, especially, when their expected handouts are not forthcoming (Ritter, 2000).

For the same reason, spot divers are disproportionately more likely to be attacked by sharks, because the spearing of fish triggers distress reflexes and panicked swimming to which a sharks sensory organs are finely tuned to recognize (RCSR, 2001). At the same time, the spearing also...

However, under normal circumstances, the fear of shark attack reflects more our primal fear of the concept of being consumed as prey than the reality of falling prey to hungry sharks.
Much more often than not, shark attacks result in very predictable circumstances and their victims nearly always contribute substantially to their own peril in one or more ways. The observation that many species of shark are capable of hand-feeding in the wild without protective enclosures ensuring the safety of the feeders illustrates how exaggerated is the general fear of unprovoked attack by sharks. At the same time, those observations also suggest that the unnatural interaction between man and a predatory species capable of inflicting great bodily harm or death on us only increases the dangerous learned association on the part of sharks between human activity and feeding.

Shark attack, while devastating in their consequences when they occur, are exceptionally rare, except where humans engage irresponsibly in behaviors know to increase the risk.

References

Ellis, R. (1989) the Book of Sharks. Knopf: New York

Perrine, D. Sharks. (1995) Voyageur: Stillwater

Research Center for Shark Research (2001); Biology of Sharks and Rays; Accessed October 14, 2007, at http://www.elasmo-research.org/index.html

Ritter, E. (2000) Anatomy of Shark Accidents; SharkInfo. Accessed, October 14, 2007, at http://www.sharkinfo.ch/SI4_99e/accidents.html

Stevens, J. (1999) Sharks. Checkmark: New York