Mysterious shark deaths do not necessarily indicate the presence of a massive, unknown marine predator. There are other, more mundane explanations. (Artwork by Thomas Finley)
As was expected, it seems that the shark's predator has been identified as a larger shark. So much for all of the premature and wild speculation. Thanks to cryptozoological researcher Dale Drinnon, who has refrained from any sort of irregular speculation as a proper investigator of unverified animals should, for bringing this to my attention.