The effective management of shared fish stocks stands as one of the great challenges towards achieving long-term sustainable fisheries. These resources account for as much as one-third of world marine capture fishery harvests. This paper explores the legal and economic aspects of the management of each of the several different categories of shared stocks, namely transboundary, highly migratory, straddling and discrete high seas stocks. The economics of the issue point to the conclusion that, with few exceptions, effective cooperation between and among states is a fundamental prerequisite for sustainable resource management.