The unpredicted mass mortality during winter period have never been scientifically studied before, hence oyster growers currently can only combat by harvesting early or moving the oysters to low salinity areas, both are not ideal and leads to economic lost. By studying and understanding the cause behind this mortality event, we can help oyster growers develop strategies to reduce harvest loss in the short term and develop a selective breeding program in the long run. The success of this project is a hope to revive the declining oyster aquaculture industry in Hong Kong