Effects of different aquaculture patterns on growth, survival and yield of diploid and triploid Portuguese oysters (Crassostrea angulata)

Abstract

Bivalve molluscs are increasingly being promoted as an alternative to land-based meat production due to their high levels of high-quality protein and lipids. The Crassostrea angulata, also known as the Portuguese oyster, has been a globally productive and renowned oyster species. In this study, we evaluated the aquaculture performance of C. angulata over two consecutive culture periods (pre-harvest phase, post-harvest phase) at different stocking densities and water depths, and compared the survival, growth and yield of diploid and triploid oysters. The experiment spanned 13 months, beginning in June 2022 and ending in June 2023. The results indicated that both stocking density and water depth significantly affected the aquaculture performance of C. angulata and exhibited distinct patterns in the two culture phases. Overall, compared to diploid C. angulata, triploid oysters showed significant culture advantages in the pre-harvest period, the growth rates and total yield of which were much higher than those of diploids. In the pre-harvest phase, the depth of 1 m and low-density culture (5 substrates/rope) favored the survival and growth of triploid oysters, while diploid C. angulata presented higher growth rates at high-density cultivation (15 substrates/rope), and the total oyster yield under 5 m culture reached a minimum for both diploids and triploids. In the post-harvest phase, the survival rate was stabilized, water depths of 1–3 m were optimal, and diploid oysters grew better at low (50 ind/cage) and medium (100 ind/cage) densities, whereas triploids had a higher growth rate of shell height at medium and high (150 ind/cage) densities. The findings of this research provide theoretical guidelines for exploring efficient C. angulata cultivation methods in the future, which will be beneficial to its commercial production.