Conservation of elements of biological diversity is an implicit but often unrecognized tenet of U.S. environmental policy. Biodiversity concerns underlie statutory requirements to “restore and maintain the biological integrity of the nation's waters” (Clean Water Act) and to prevent extinction (Endangered Species Act and Marine Mammal Protection Act). Yet without an explicit policy and strategy to protect biological diversity, biodiversity is being reduced at an alarming rate. A national strategy to conserve biodiversity should proceed on five fronts: research, establishment of protected areas, conservation in multiple-use areas, recovery of endangered species and ecosystems, and education. It is inappropriate to rely on protected areas as the primary conservation measure for most aquatic systems, which need substantial restoration and management. Recovery of endangered aquatic biota must be accomplished through an ecosystem approach. Legislation to make conservation of biodiversity a national policy and to direct a national biodiversity strategy has been introduced in Congress.