This volume presents a synthesis of basic biological and conservation data for more than 30 species of sturgeons (Acipenseridae), paddlefishes (Polyodontidae) and their fossil allies in the order Acipenseriformes. Since the Jurassic, the four families of sturgeon-like fish have been restricted to the Holarctic, where until very recently they flourished in most major river systems. Today, however, virtually all species of sturgeons and paddlefishes face difficult conservation issues. Papers in the first section of this volume examine paleontology, systematics, evolution and basic biology of Acipenseriformes. The second section of this volume details current conservation status for most of the world's living species of Acipenseriformes. These papers mark the first attempt to make such a global review of recent data from across the northern hemisphere. The emerging picture is discouraging, for negative anthropogenic impacts range from overfishing to water pollution, to dams and water diversion projects, and all species are threatened to some degree. The third section of the volume considers specific human impacts and responses to conservation issues. These include: the Aral Sea ecological disaster and its impact on native sturgeons; a review of methods for restoring sturgeon populations; the use of molecular techniques in developing conservation strategies; the extreme sensitivity of sturgeons and paddlefishes to overfishing; and the history of a recently convicted caviar poaching ring. The volume's summary reviews the status of all extant species and notes future directions for research on behavior, ecology and population biology that could lead to better co-ordinated international conservation efforts.