Humans are not sharks natural food. More often than not shark attacks are from mistaken identity. Great Whites are opportunists and will take a bite out of pretty much anything to see if it is edible. The so called 'investigative bite' can obviously have devastating effects, occassionally resulting in the death of the victim. Most sharks will take a bite, realise we are not there normal food and move on. This however is not always the case. A GWS prefers the soft fatty tissue of a seal to human flesh which is very boney in comparison. It has nothing to do with whether we taste good or not!
Shark attacks are most likely on the rise due to over fishing and mans ever growing intest in aqua sports which are bringing us closer together.
However, I find it deplorable that we see fit to go hunting an animal that is doing what it does naturally. The sea is not our domain, never has been. Sure it's our hunting ground but in this case the hunter became the hunted. The guy knew the perils of his actions, knew the dangers of spear fishing in known shark territory but still put himself in great danger despite this. Sadly he is reaping the consequences of his actions and while I sympathise, you can hardly blame the shark for doing what it does naturally. It sensed distress, it smelt the blood, it killed. Most victims of shark attacks who live to tell the tale will not blame the shark so why do the authorities see fit to go on a 'man-hunt', especially when in this case they would clearly have no idea which shark killed the diver?
By the same respect of some of the ridiculous arguements put forward in this thread: If a diver went swimming in the waters off Seal island during the seal birthing season (when GWS are regularly filmed jumping from the water) and the diver happened to be killed. Should we then go and slaughter all of the sharks in the vicinity? No we shouldn't and wouldn't, why? Because the diver was being irresponsible. I see little difference from this example to the fateful experience the spear fisherman has had.
A shark is no more of a risk than mans stupidity and ignorance.