As I know that shark bites occur more frequently in murky water and than in some place of Australia sea. They are attracted by lights, noise, or splashing, and smell. For theses reasons surface swimming should be kept to a minimum, in shark waters. Research shows that bright colors attract sharks more than dark objects, so it is better for divers to wear dark colors. Blood in the water can attract sharks from long distances. They can sense blood in the water in concentrations as little as 4 parts per million. Bleeding into the water by a diver or swimmer may not go unnoticed. Women who are menstruating are recommended to wear tampons. As to any evidence that the menstrual cycle can increase the hazard of shark attack is inconclusive. It is believed that sharks are only attracted by fresh blood of human being. So be aware with this one.