What the shark is doing is fishing. It has no interest in the guy on the kayak, unless of course he ended up in the water. The shark is just waiting to pick off a hooked fish that is unable to escape. It's simply looking for an easy meal, which in a technical sense, makes it semi-domesticated. They are not hunting naturally as they have done for millions of years. They are using people fishing on boats as a tool for an easy meal. Imagine if he was in an inflatable kayak. He would have been lunch!! This is a scary video to watch because of that: stay safe!