The state Division of Marine Fisheries announced the determination Tuesday after speaking with the swimmer, examining his injuries and working with the curator of the International Shark Attack File at the Florida Museum of Natural History. Officials had said last week the attack likely was by a great white, the type seen in the "Jaws" movies.
Denver resident Christopher Myers was bitten on his legs July 30 while swimming off Ballston Beach in Truro. He joked about the experience when he was released from a hospital Friday with one leg in a cast and the other bandaged.
Great white sightings off the Massachusetts coast have increased in recent years. Experts say it's likely because there are more seals, which sharks eat.