On-site biofouling removal enhances the nutritional and gustatory quality of oysters from suspension aquaculture and the recovery of essential biomolecules for human consumption

We experimentally tested the effects of on-site biofouling removal (BR) via heat treatment on the biomolecule contents of Pacific oysters and the bay-scale recovery of these biomolecules through the harvest of farmed oysters from suspension aquaculture in a temperate bay. At harvest after an 18-month cultivation period, oysters treated at the 13th month showed 18 % higher soft body weights and increased contents of certain biomolecules compared to untreated (UN) oysters. Specifically, BR oysters had 15 % higher eicosapentaenoic acid (EPA) content and 13 % higher docosahexaenoic acid (DHA) content than UN oysters. The glycogen content of BR oysters was 54 % higher, suggesting enhanced energy storage and potentially improved sweetness. BR likely reduced food competition between oysters and fouling organisms, predominantly mussels, leading to the higher biomolecule contents. If BR were expanded to cover the entire bay (from the current 10–100 %), the recovery of EPA and DHA through the harvest of farmed oysters would increase by 28 %, reaching 869 kg in a 1.5-year production cycle. Biofouling removal (BR) did not significantly affect the content of essential amino acids (AAs), gustatory-related AAs, or taurine in oysters. However, due to improved oyster biomass production, BR is estimated to potentially increase the recovery of these biomolecules by approximately 12 %. In conclusion, on-site BR is a straightforward and effective method for enhancing the levels of certain nutritional and gustatory-related biomolecules in cultivated oysters while simultaneously increasing the recovery of nutritionally important biomolecules for human consumption.