Oyster is an important economic shellfish in Taiwan. How to effectively harvest good-quality oyster spat is the most critical process in the entire oyster farming industry. In recent years, the number of natural oyster spat has often undergone drastic changes during the seedling period, resulting in unstable harvests of the seedling oysters, and affecting the downstream oyster farmers' demand for oyster spat. In this study, standard seedling piles were used to investigate and analyze the best seedling water layer distribution at 11 locations of Yunlin. At the same time, oyster shell strings were used to verify the effectiveness of spats harvesting. In the same time, imported oysters mixed with domestic oysters have confused the market price. Therefore, it is necessary to develop corresponding oyster origin identification technology. This project establishes feasible oyster sampling and standard operating procedures based on stable isotope analysis technology. It is planned to build a stable isotope fingerprint database of Taiwanese oysters based on the difference of isotope ratios in different environments as a standard for identifying the origin of domestic oysters.