The debate on the causes of the Crise Requin on Reunion Island is a difficult one. The most accurate way of putting it would be that nobody knows exactly why the attacks happen more often.
People that said they knew the exact reason seemed to be stating wrong explanations or only telling part of the truth. There are however many reasons that I have heard regularly and some of them make more sense than others.
The elimination of the larger sharks on drumlines (mostly bull and tiger sharks, but recently even a Great White shark) is a controversial method that is met with increasing resistance. Resistance is growing due to its tendency to create unwanted bycatch and the already unsustainable levels of overfishing on shark species worldwide. Also, many people state that the drumlines with bait actually bring in sharks from a distance and therefore actually increase the risk of interactions with sharks.
On top of that removing the sharks from the ocean is also negatively affecting shark populations regionally. The sharks from Reunion Island have been tracked to the Southern African coastline were a vibrant shark tourism industry is present. Needless to say shark operators on the African continent are not pleased with the fact that the sharks they make their profit from are killed elsewhere.
Finally, biologists and scientists indicate that these sharks play a vital role in the marine ecosystem around Reunion and taking them out could well make matters worse..
Please also find the following blogpost on the Crise Requin.