Optimizing the post-harvest salting of cultured oysters (Crassostrea virginica) using a recirculating wet storage system by monitoring adductor hemolymph osmolality

Abstract

The oyster aquaculture industry is steadily growing in the United States, principally driven by the rise of small farms. With an increasingly crowded marketplace, farmers are searching for methods to diversify their crops and remain competitive. Enhancing oyster liquor in wet storage while preserving the water's signature flavor, or ‘merroir,’ is one way to create a new product line and differentiate crops, especially with oysters grown in low-salinity environments. Previously, growers have attempted to increase the salinity of their product by ‘finishing’ their oysters in a saltier water body; however, mass mortality may accompany such a transfer. Therefore, implementing a wet storage system may be a useful intermediary step to reduce crop mortality prior to ‘finishing’ oysters in alternative waters. This project sought to understand how to effectively use recirculating aquaculture systems (RAS) as wet storage to expose harvested oysters to a chosen salinity and temperature to function as a modified wet storage system. Additionally, this experiment describes the effects of both short-term and long-term salinity and temperature stress on the survival, condition index, and shelf life of adult oysters. The shelf life and rate of osmoconformity of low-salinity adult oysters depend on ambient temperature and acute changes in salinity. While increasing ambient temperature improves the rate of hemolymph osmoconformity, we observed high mortality above 25 °C. Additionally, the shelf life of oysters was negatively affected by the length of exposure time to higher salinity and increasing temperature. These data can guide oyster growers in low-salinity regions who wish to diversify their product using recirculating tanks or better understand the potential risks associated with transferring cultured oysters across water bodies of varying salinity.