Most wild oyster populations globally declined precipitously throughout the 20th century. The shellfish aquaculture industry has grown rapidly to meet the growing demand for seafood. Although shellfish aquaculture is one of the most sustainable sources of animal protein, it still uses antiquated equipment, such as dredges, that may impact water quality and benthic habitats within and adjacent to on-bottom leases. Dredges are commonly used to manage and harvest on-bottom oyster, yet they lack precision. Dredges indiscriminately collect crops and may damage smaller, less mature individuals. Compared to other methods (i.e., diver or tongs) they also may fail to collect many available oysters. Additionally, dredging disturbs bottom substrate, creating suspended sediment plumes (SSPs) that temporarily attenuate light and may impair water quality.
To improve crop management and increase sustainability, a smart sustainable shellfish aquaculture management (S3AM) framework that utilizes a remote underwater vehicle (RUVs) and advanced software for crop detection, automated navigation, and other features is currently being developed. This technology is unproven and comparing its usefulness and ecological footprint to traditional methods is critical for approval and adoption from industry members and other stakeholders.
To lay the groundwork for this comparison we conducted a study to better understand natural variability on active oyster leases and developed methods for characterizing SSPs. Working in and adjacent to active oyster leases in Chesapeake Bay, a YSI EXO2 Sonde routinely measured background dissolved oxygen, chlorophyll, and total dissolved solids. These measurements were mapped into a 3D spatial grid to provide researchers with more information how water quality changes with depth in on-bottom oyster leases. To characterize SSPs from dredging activity, we measured the sedimentation and direction of the plumes using sediment traps and an array of light attenuation sensors placed radially at multiple depths near the impact site. The concentration of the plume was measured with the EXO2 in TSS values.
Novel data generated by this experiment includes spatial variability of conditions within leases, and ecological footprint of advanced RUV technology within an aquaculture setting. The overall goal of this project is to improve the understanding of how RUV technology can enhance sustainable shellfish aquaculture.