Shellfish Aquaculture Resilience

Co-culture of grazers and oysters: a nature-based solution approach for biofouling control

Project lead – Dr. Darien Mizuta

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 Virginia Eastern Shore, especially in traditional bottom cages (which tend to reduce social conflicts). 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 seeking natural and most sustainable solutions is the best strategy.

This work explores if the co-culture of suspension-feeding Eastern oysters (Crassostrea virginica) and native grazers, Atlantic Purple Sea urchins (Arbacia punctulata), and periwinkles (Littorina littorea), representing a possible effective natural solution to control biofouling on farming bags without compromising - and instead potentially improving – the main product, oysters. Two different species’ sizes and stocking densities are being tested for comparing potential effects on the cleanliness of cages and species performance 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 improve the bivalve quality and bring a secondary additional marketable product, and income, for the farmer.

Predicting optimal splitting of oyster crops

Project lead – Matt LaGanke

My project focuses on predicting the growth rates of cage-cultured oysters to help growers manage their crop proactively rather than reactively. As oysters grow, they are graded into similar size classes and then split into containers at lower densities for additional room to grow. Experienced growers are in tune with the relative growth rates year-round - pick up in the spring, take off in the summer, and slow down in the winter - and have a general sense of when to process. I'm investigating how different predictive quantitative models of growth can aid in fine-tuning the planning and management aspect so that oysters are processed on time to limit the extra labor associated with processing too soon or too late. I'm comparing three predictive growth models based on different inputs and mechanisms but focused on the same output – oyster growth rate.