According to author Peter Benchley, he came up with the title 20 minutes before the book was supposed to go into production. He'd thought of many options he wasn't crazy about—A Stillness in the Water, A Silence in the Deep, The Jaws of Death, The Jaws of Leviathan. But the only title that he and the editor could agree on was just Jaws. It was short and sweet and fit nicely on the cover of the book (source). Good call, guys.