The oyster population in the Maryland portion ot Chesapeake Bay, USA, has declined by more than 50-Iold since the early part of this century. The paper presents evidence that the mechanical destruction of habitat and stock over fishing have been important factors in the decline, even thouqh it is commonly thought that 'water quality' and, more recently, oyster diseases are critical. Quantitative analyses show that the long-term decline 01 oysters largely resuIts from habitat loss associated with intense fishing pressure early in this century and stock over fishing from early in the century throuqh recent limes. Furthermore, the major ecological effects on Chesapeake Bay occurred weIl betore World War II, before industrialization and the reported prevalence of disease. To effect the recovery of the ailing Chesapeake Bay oyster stock, a 4-point management strategy is proposed.