Towards sustainable oyster farming: A field-based modeling approach in Hong Kong

Oysters are essential nutrient-rich carbon neutral seafood delicacy for growing middle-class population, therefore, its expansion to new culture areas is important for securing seafood supply security. Notably, the demand for cultured Hong Kong (HK) oysters (Crassostrea hongkongensis) has recently increased due its added nutritional and taste related values However, increasing HK oyster production is becoming challenging as the optimal low salinity estuarine areas for HK oyster growth are threatened by pollution and land reclamation. When the aquaculture zone is moved away from the low salinity estuaries to high salinity coastal areas (with relatively less algal productivity), increase in salinity and changes in many other environmental factors becomes a primary abiotic stress to these oysters. This study assessed the growth and survival rates of Hong Kong oysters across three distinct aquaculture environments to identify the environmental factors that promote high growth yield and low mortality, using Hong Kong's 700-year-old estuarine oyster farming ecosystem as a model. Specifically, a full factorial, central composite design (CCD) with four variables including salinity, chlorophyll, dissolved oxygen, and nitrites was used to evaluate oyster growth and survival. Results indicated that salinity and chlorophyll were the major influencing factor, and the model predicted a maximum incremental growth up to 9.128 % per month and survival of 100 % under optimized conditions in Hong Kong's Deep Bay. Furthermore, this study provides a scientific basis for the adaptive practices adopted by locals, informing the government's management and future development plans in Deep Bay, ultimately enhancing sustainable oyster cultivation.