Survey of Oyster Diseases in the Galveston Bay Area - Survey of Oyster Populations and Associated Organisms

Mortalities among tray-held oysters (Crassostrea virginica) were studied during a two year period at stations located on Switchover Reef and Hannah Reef. In 1963 mortalities at both stations showed similar patterns, increasing during the summer months (with peaks in August-September) and declining during the fall and winter. The summer mortalities were associated with high infections of Dermocystidium marinum. From March through December 1963 oysters at the Switchover station suffered a mortality of 52.6%. From April through December, 1963 a mortality of 42.2% occurred among the Hanna oysters.