Great White Invasion

Great white sharks, in ever-increasing numbers, are now being routinely sighted off some of the world's most popular beaches in California, Australia and South Africa. Along these coastlines, the Great Whites are suddenly and inexplicably appearing close to the shore, in dangerous proximity to surfers and swimmers. What has prompted this 'Great White Invasion' and what is the potential threat to humans that share the water with these animals? (Discovery)