California Sea Grant College Program

The goal of this project was to investigate and document the presence of disease agents in cultured and wild oyster populations throughout California. This is the first comprehensive survey to be conducted since that of Katkansky and Warner in the late 1960s to early 1970s (Katkansky and Warner, 1974). Particular emphasis was placed on detection of the agent of Denman Island Disease (Mikrocytos mackini, Farley et al., 1988). This pathogen of the Pacific oyster (Crassostrea gigas) was detected in the State of Washington in 2002, and many California oyster growers receive seed from Washington State. All major populations of farmed and feral commercial oysters and wild native oysters Ostrea lurida were targeted for sampling. Sufficient numbers from each population were collected so that relatively rare pathogens should have been detected when they are present.