Oyster aquaculture is an integral part of the economic and cultural landscape in the Gulf of Mexico. However, the region’s lack of oyster hatcheries and nurseries could threaten the industry’s sustainability because farmers may not have reliable access to oyster "seed" (a juvenile life stage). One solution is for farmers to build their own nurseries and raise seed. This project aimed to facilitate successful farmer-run nurseries by advancing quality management techniques in oyster nurseries. Farmers need to raise high-quality seed to plant on their farms in a time and resource-efficient manner. Farmers cannot control all aspects of seed quality. However, farmers may be able to influence seed quality and prevent mortalities on the farm during the nursery grow-out phase with seed conditioning practices. While not common in North American oyster farming, farmers have practiced seed conditioning or “hardening” for decades in Japan and Korea. Seed hardening entails raising nursery-aged oysters in stressful environmental conditions to increase survival rates during the farm grow-out stage. This study will examine if incorporating desiccation practices into routine nursery operations can decrease farm mortality without significantly increasing the nursery labor required.
This ongoing study began in July of 2024 at the Louisiana Sea Grant Hatchery in Grand Isle, LA. Two conditioning treatments were tested to raise diploid oysters: a 16-hour, overnight desiccation treatment (the stress treatment) and a control treatment. The trial began after oyster seed reached a size of 2 – 4 mm (R2 size class) and were transferred into silo upwellers. From 7/11 to 8/06, the total number of seed in each size class (R2, R4, and R6) for each treatment was counted weekly (Figure 1). By the second week of the experiment, 7/23, over 30% of seed in the control treatment had grown into the R4 and R6 size classes. Conversely, an average of 90% of seed in the stress treatment remained in the smallest size class, R2, for the duration of the nursery experiment. After four weeks in the nursery, a portion of seed from both treatments was transferred into floating cages to track growth and mortality on the farm. Seed will be measured and counted monthly for one year to track growth and mortality.