As I understand it, the bulls used to migrate through the area. One or more dive shops started feeding them so they could "guarantee" sharks to their customers.
The sharks became resident and were seen more and more, not just where they were fed but shallower as well. Some dive ops began seeing them on shallow dive sites, even on resort course dives and snorkel trips. Bulls are quite happy in shallow water.
Changing their behavior this way was, and continues to be, a mistake. A lot of people were saying and thinking a couple years ago that this was going to lead to a problem when some snorkeler or swimmer got chomped on. Sure enough, some poor woman doing nothing but wading in shallow water got bitten and almost died.
At least according to the victim and witnesses who were there, the victim was not harassing the shark or crowding it during birth, or any of the other "stuff" the local tourism board put out.
No big surprise...the fishermen then went out to rid the waters of the vicious sharks.
As far as I am concerned, the dive ops that chum for sharks share responsibility for the recent shark slaughter with fishermen...it was inevitable. I also think they have blame for the woman injured. Not legally, but morally. Feeding bull sharks near popular beaches with snorkeling, swimming, etc. is wrong.
It is a huge mistake for people to be feeding these bull sharks and changing their behavior. I wish they had not been killed, but if Playa and Cancun can either have sharks and shark attacks or no sharks/no attacks, which do you think they will pick?
If you say they will pick sharks, I have some nice seaside property in Nebraska I would like to sell you.