Book excerpt: Millions of people are moving from rural areas to coastal cities. Meeting the basic human needs for protein foods in the future will be a difficult challenge. Fishery products are the world's most important source of animal protein, which has led to a doubling of the demand for fish since the 1950s. As we can not expect to catch more food from the sea, we must turn to farming the waters, not just hunting them. The new challenge for planners now is to accelerate aquaculture development and to plan for new production, making urban areas of production, particularly recycled urban wastewater. This book includes papers from authors in the U.S., Europe, and Asia that review these developing issues from the perspective of both developed and developing countries.