Interesting video on shark behaviour when interacting with humans. Now because this is on youtube, you may need to take it with a pinch of salt unless there are any shark experts out there that can confirm or deny the information contained within. Still worth a few minutes of your time. Embedded video below and youtube link below that for those that don't have flash enabled browser.
Bottom line, according to these guys, most humans don't have enough fat content for their liking and we're too bony for their slow digestive system. Also the risk factor for the sharks is too great for the potential gains in trying to eat us as there's more potential for injury, so we're not worth the effort. They're far more afraid of us than we are of them.
And quite rightly so. Using data on shark catches, discards and mortality rates worldwide, the researchers estimated that approximately 100 million sharks are killed per year by humans. However, they add that this is a conservative estimate, and the true number could be as high as 273 million sharks killed annually by humans.
No wonder they're afraid of us as we're systematically wiping them off the face of the planet. Next time you see a shark whilst diving, be grateful as at this rate, they could disappear entirely and that would be a tragic loss of epic proportions for us.