I like the alberta references!
I am certainly not advocating "conserve" at all costs, just that a "cull" is an extreme over-reaction to an exceptional incident. Take a look at the following threads:
http://www.scubaboard.com/forums/mexico/366384-playa-del-carmen-sharks-wiped-out.html and
http://www.scubaboard.com/forums/mexico/359631-playa-del-carmen-sharks-killed.html
The fisherman are not taking "a few man-killing sharks from the sea." By the way "man-killing" is intended to invoke a emotional reaction as well, there was not even a fatality in this case, and I do not know if there has ever been a bull shark fatality in the area. In regards to the fishing, there is no control, no quota, it is being done unchecked for pure profit. There is no indication that any of those sharks taken in the late 2010 incidents were of any threat to a human population. I do not think that the taking of so many sharks can be described as anything less than a slaughter. The irony here is that if there could be a sustainable commercial shark fishery, I would have no issues with that, just as I have no issues with a sustainable lobster fishery (yum) or a sustainable cod fishery. The problem is that in practice, generally shark fishing has not been done sustainably, and often is done in a cruel and wasteful fashion (finning).
I do not know any specifics about this encounter, and yes, if the animal was "seeking out" humans for food, or using the shallow waters for hunting ground (do they even do this???), it should be destroyed, just as the bears in banff and jasper are when they attack humans. The issue with the bears is that the park rangers try to "train" bears to fear humans through non-leathal means, but sometimes they fail resulting in bad interactions and the neccessary destruction of the offending animal (history has shown that these animals will tend to repeat their behaviour). In these cases a single animal is destroyed in order to reduce the likelyhood of a future incident, while maintaining the bulk of the population.
I am no environmentalists (see I'm from Alberta, I drive a big gas guzzling pickup truck, I support our oilsands, and vote Conservative, gasp!) but I do believe in balancing our impact on our environment. I don't think we should all go live in trees and become vegetarians, but I do think we have a duty to protect the areas we use for our recreation so it can be enjoyed by future generations. Lets use the resources that exist around us to make our lives better and more comfortable, just do it in a way that is generally sustainable. The point is not to conserve at all costs, but to try and maintain a population of an apex predator and thus to help to maintain the reef systems so I can selfishly keep going back to this wonderful scuba playground.
As I have previously said, and many other threads on this board mirror, the irresponsible dive ops that are doing feeding dives are at best damaging the sharks by conditioning them and changing their behavior and at worst endangering the divers that are their customers and the public as a whole. In a perfect world it would be those dive ops who would bear the brunt of the blame in these issues.
I truly feel for the swimmer, but I still believe this to be an isolated incident.