I have on reliable advice that a mayor of an Iranian town on the Caspian recommended a means of discouraging mixed-sex swimming: Introducing sharks into the Caspian Sea. He allegedly even tried and failed. Little did he know that there are fresh-water sharks in the world. http://en.wikipedia.org/wiki/Freshwater_shark. Thankfully, he is not that knowledgeable.
Perhaps the worst idea…
Sayings of the Preachers 