Oyster culture is a longstanding traditional business in the Chesapeake Bay where environmental conditions support the production of shellfish that can be marketed under different grades (size, shape), and taste profiles, including from sweet to briny, with an increasing emphasis on aspects of quality. The control of biofouling, which is exacerbated in high salinity areas, is still an issue for farming on the Eastern Shore, especially in traditional and conflict-reducing bottom cages. Physical methods for biofouling control are time and staff-consuming and can be a considerable expense for the farmer, while types of anti-fouling paints are either prohibited or under development (natural base). Recognizing these limitations, growers have sought alternatives with an interest in more sustainable forms of aquaculture (conservation, restorative, regenerative), seeking natural and most sustainable solutions is the best strategy.
Within the Nature-based Solutions (NbS) framework from the United Nation to which aquaculture can potentially abide to, the farming industry should take advantage of ideas that are both environmentally friendly and provide the best social-economic outcomes. One such approach is the co-culture of different species with a focus on positive ecological interactions, higher revenue for the farmer, and possibly additional marketability.
Within that scope, this work explores if the co-culture of suspension feeding Eastern oysters (Crassostrea virginica) and native grazers, Atlantic Purple Sea urchins (Arbacia punctulata), represents an effective (or not) natural solution to control biofouling on farming bags (Figure 1) without compromising – and instead potentially improving - main product. Two different urchin sizes and urchin stocking densities are being tested for comparing potential effects on the cleanliness of cages and species conditions, while maintaining available space inside the farming gear and species survival, which will be assessed for both species. Broadly, we expect the advantage of deploying urchins with oysters to be two-fold depending on the target urchin species: in locations where the urchin species have become a biological nuisance, the species can be harvested from nature for grow-out in aquaculture devices; in locations where a past fishery has led to low species stocks, (future) demand for hatchery seed would support another farmed product for the market without the need to further alter natural stocks and possibly contribute to restoration efforts. ¨