Document Type



Virginia Institute of Marine Science

VIMS Department/Program

Marine Advisory Program (MAP)

Publication Date



Fishery Resource Grant FRG 2003-01


This validation study was conducted during the months of July, August and Sept., 2003. The Food and Drug Administration and the Interstate Shellfish Sanitation Conference require that oysters used for a validation study are collected during the same processing day, are from the same lot of shellfish, and have an adjusted geometric mean (AGM) MPN of at least I 00,000/g of Vibrio vulnificus as an initial load. The oysters were removed from refrigerated storage and held at 71 °F (21 °C) for 40-45 hours prior to freezing in order to achieve a minimum AGM of 100,000/g Vibrio vulnificus . After quick freezing the oysters at -70°F (-57°C) for nine minutes, approximately 8-10 weeks of frozen storage at 0°F (-l 8°C) were required to reduce V. vulnificus levels from 105 MPN/g to less than 30MPN/g. Initial V. vulnificus numbers in excess of 1,000,000/g, required prolonged frozen storage (>20 weeks) of the oysters at 0°F (-18°C) to reduce V. vulnificus numbers to less than 30MPN/g.


Oyster aquaculture