this is the instance walter zolts jr. realizes he's being followed, stalked by a healthy are 12 to 15-foot shark which may or may not have been a great white. you've seen the picture everybody is talking about. the alone kayaker, the shark behind. >> we're not 100% it's a great white shark, based on the fin shape itself which is remarkably similar. >> reporter: but there is real concern among some experts who are seeing evidence of an uptick in great whites off the east coast. >> i've been telling people for 27 years not to worry about sharks. not to worry about shark attacks. now, i'm advising towns when or when not to close beaches. >> reporter: but skomo questions movies like "jaws" with a mechanical white shark have given great whites a bad rap. >> we often think of sharks as killing machines. that's not wha we're actually killing them at a far greater pace than they're biting us. >> reporter: they don't actually hunt humans but what makes them potentially dangerous are these little guys. the seals that have returned