Sharks are the most successful predators in the ocean.
Their only real enemies are other sharks and humans. Of these two, humans are the only serious threat to the migration success of sharks. Humans threaten sharks and their migration success in several ways. These include killing sharks for their commercial value, for sport, in response to the media, and to protect swimmers at public beaches. Sharks do feed on each other, though this is less likely than we would think since sharks are highly specialized hunters with preferred food sources.