There were two cage breach incidents in 2016. The first was the result of an operator putting a bag of chum inside a cage and having divers basically dance and jump around on it to disperse the smell into the water. A large white shark attempted to get into the cage by coming through the top. The use of a bag of chum inside a cage wasn't a one time thing with this particular operator. I remember a video of divers dancing on this operator's chum bag inside a cage posted on ScubaBoard.
The second incident was a smaller white shark that hit a cage hard enough to breach it and join the diver inside... until the diver exited through the bottom of the cage to avoid the shark.
These incidents prompted the Mexican government to call Guadalupe operators to a 'Come to Jesus' type meeting to present evidence of operators violating the biosphere rules. If I recall correctly, fines were levied against the operators who were violating the rules. The government began putting observers on the operators' boats in an effort to curtail the bad practices.
Another issue that doesn't get discussed much relates to some of the film production work that has been done at the Isla Guadalupe. Many of the activities film crews engaged in had little to do with legitimate scientific study and more to do with stunts. For example, Discovery ran a program a while back that had one of their Shark Week regulars floating on the surface at Guadalupe inside a plexiglas box. Of course, the outcome of this stunt was predictable; a large white shark decided the diver looked like a sea lion and munched the plexiglas box. I had visited with the diver who did this stunt a couple of years before he did the box thing and told him it was disappointing to see these kinds of programs. I felt Discovery was missing opportunities to focus on educating people about sharks. His response was that the network was really focused on attracting viewers and extreme, outrageous program themes were what brought in viewers. Frankly, it's not hard to find examples of this type of Shark Week programing. Welcome to the stupid world of reality televison.
I sincerely believe the closure will have negative impacts upon the Guadalupe Biosphere. Without a doubt, there will be illegal fishing activities occurring at Isla Guadalupe without people out there to observe what's going on.
-AZTinman