Development of a nursery upweller for young oysters in tropical mangrove estuaries

In this study, the aim was to prototype a small intermediate cultivation device using commercially available materials based on the passive flow-type upwelling system. Young oysters were housed in the device on a farm, and a test run was conducted. To evaluate the effect on cultivation, net cage and cage + aeration groups were established for comparison, and problems associated with the field operation of the device were analyzed. The device promoted growth, as indicated by the increased levels of phytopigments in the midgut gland tissues and new shell formation in the oysters. However, regular cleaning for antifouling measures was necessary at least once a week to use this device in regions with brackish mangrove water. Further simplification of the device structure can aid in its widespread use for fishermen.