Tumbling is important for the shaping of oysters and forming a deeper cup, creating a marketable and meatier oyster. However, this process is labor intensive and often requires expensive, gas-powered, and noisy equipment that can be a barrier for farmers wanting to grow their business. This project aims to use the energy from the fluctuating tides to tumble bags on a suspended longline system - a design that works alongside the environment while reducing farmers’ labor. Previous experiments have explored tidal energy for shaping an oyster during the final four-month “finishing” period; however, this study begins a long-term project that will follow the oyster growth from spat to market size.
There was no difference in shell growth among the three farm systems. However, other research with larger oysters suggests that differences in oyster performance start to appear after three months. Intertidal bags followed a complete 180º motion that followed the tides. The sensors were limited to 180º motion, not allowing us to assess if the bags were achieving a 360º rotation. Shallow subtidal bags achieved a 100º motion. Subtidal bags had greater average acceleration (~10.9 m/s2) than intertidal bags (~10.3 m/s2).
No biofouling was observed on the control or intertidal bags. There was small but noticeable biofouling on the subtidal bags one week after deployment. The biofouling on the subtidal bags covered only half of the bag, suggesting that the bag was not completely flipping and was only exposing one side to the sun.