When I was a kid playing Vice City back in the day one of the things I enjoyed most was the sharks. I never saw them in the open ocean too often but I do remember seeing them by the docks next to the light house in ocean beach quite a bit. If you knocked alot of people into the water it seemed to help spawn sharks a little more frequently or it might just be a coincidence. Of course the sharks never ate anyone just swam around still fun though, try it out if your bored seemed to work for me. I'm probably a day late and a dollar short with this one, more like a few years. I know this isn't a myth as we all know sharks are in Vice City.
It's a lucid reference to the Shark Attacks. Shark Attacks are mentioned in the Vice City Manual, it's likely that Rockstar programmed the sharks to appear at times to give an impression of Shark Attacks. It's a great discovery for sure, nostalgic :). I have mentioned this bona fide fact on the main page. Do check this out: Megalodon Shark.