i saw something similar with a guy swimming and doing all kinds of crazy stuff with tiger sharks and another aggressive species. he even went into the water after pouring blood and throwing meat into it.
basically he said that if the shark knows youre human, he has not that much interest in you. sometimes shark mistakes humans for something else and probably more often they will be nosy and wanna find out whats that weird thing. too bad they dont have hands to check it out, so they have to bite into it
in all seriousness, i read that 3 times, 1st time i thought what the fuck is he on about, read it again and thought, this fuckbag has to be kidding, read it once more and decided calling you a fuckbag wasnt good enough - sick-as-aids