ABSTRACT
In early summer of 1960, I came for the first time to the Oxford Biological Laboratory on Maryland’s Eastern Shore. As a new shellfish research laboratory of the National Marine Fisheries Service, it had been confronted in the year before my arrival with high mortalities of oysters due apparently to a disease of unknown origin. Oysters of the Middle Atlantic region had died in great numbers beginning in 1957 in Delaware Bay and in 1959 in Chesapeake Bay, and production had declined precipitously. The laboratory’s programs were being reoriented to develop information about the cause. During the 1960s and 1970s, staff members worked full-time on the problem, as did research scientists at several state and university laboratories in the Middle Atlantic area. The pathogen (a protozoan named Haplosporidium nelsoni) and its life cycle were described, as were some controlling environmental factors (especially salinity and temperature), but the origin of the disease agent and its method of natural transmission remained a mystery for many years thereafter.
