Bull Sharks live in the coastal regions of the world at time traveling up fresh water rivers miles. THis from Wikipedia.
The Discovery Channel stated in Shark Week episodes “Ocean of Fear” that the Indianapolis sinking resulted in the most shark attacks on humans in history, and attributes the attacks to the oceanic whitetip shark species. Tiger sharks might have also killed some of the survivors. The same show attributed most of the deaths on Indianapolis to exposure, salt poisoning and thirst, with the dead being dragged off by sharks.[14]