Few places in the world can claim such a diversity of species as the Gulf of California (Sea of Cortez), with its 6,000 recorded animal species estimated to be half the number actually living in its waters. So rich are the Gulf's water that over a half-million tons of seafood are taken from them annually—and this figure does not count the wasted by-catch, which would triple or quadruple that tonnage. This timely book provides a benchmark for understanding the Gulf's extraordinary diversity, how it is threatened, and in what ways it is—or should be—protected. In spite of its dazzling richness, most of the Gulf's coastline now harbors but a pale shadow of the diversity that existed just a half-century ago. Recommendations based on sound, careful science must guide Mexico in moving forward to protect the Gulf of California. This edited volume contains contributions by twenty-four Gulf of California experts, from both sides of the U.S.-Mexico border. From the origins of the Gulf to its physical and chemical characteristics, from urgently needed conservation alternatives for fisheries and the entire Gulf ecosystem to information about its invertebrates, fishes, cetaceans, and sea turtles, this thought-provoking book provides new insights and clear paths to achieve sustainable use solidly based on robust science. The interdisciplinary, international cooperation involved in creating this much-needed collection provides a model for achieving success in answering critically important questions about a precious but rapidly disappearing ecological treasure.