The ghandi approach....
Get an old board, preferably easy to paddle and dinged up and just sit on the bloke for a whole session, sit just on his outside and paddle for every little ripple he looks at... If he goes you go, if he pulls back flick off and sit next to him again. No violence, just shadow him and try to get under his skin. After a while he'll no doubt ask what's going on,.. if this approach fails see the movie point break for further tips...

This tactic also works better if you can rope in a few mates and kind just encircle him and just try to make his surf unpleasant as possible, more mates is good cause you can still all sneak a few in while paddling around laughing at old mate.