Some of the people I've talked to made reference to chumming these sharks in, and in close proximity to the mainland beaches. Thanks for your post jfcl01.......
We have been diving with Dive Aventuras (Nils' shop) for about a decade. I cannot say enough for the professionalism of Nils, his divemasters, and the other members of his crew.
In those ten years, we have seen free-swimming Bull Sharks in the waters off Puerto Aventuras twice. No chum, no squeezing soda bottles, nothing but a beautiful creature swimming wild in it's environment.
Make no mistake, we have also fallen prey to the hype of diving with the Bull Sharks with a PDC shop, and regret that we did.
If you really want to see Bull Sharks, go to Costa Rica, and dive Bat Island, we've been there twice, and seen multiple Bull Sharks each time.
I applaud Nils for his courage to speak out, and I hope you take his advice.