Bottlenose dolphins suffering food shortages may be killing sibling species to take out the competition, scientists have warned. A series of dead porpoises and young bottlenose dolphins washed up have borne the animalâs teeth marks. The appearance of a rare baby Rissoâs dolphin body on a beach in the Scilly Isles raised fears that bottlenose dolphins may be becoming more aggressive in their desperate search for food. The latest victim was young enough to still be dependent on its mother for nourishment and researchers believe it was killed by an adult predator. Rissoâs dolphins feed on things like squid and cuttlefish and octopus, which are rarely eaten by bottlenose dolphin.