Evaluation of a Mechanical Grader for the Improvement of the Aquaculture Production of the Eastern Oyster, Crassostrea virginica, in the Northern Gulf of Mexico

Abstract

In order to develop culture regiments that increase oyster product quality and profitability, commercially available oyster aquaculture growout gear, a rotary style mechanical grader (“tumbler”) and three handling treatments were evaluated for their ability to physically impact oyster morphology, increase the consistency of morphology, reduce exterior biofouling and reduce mortality. The gear and the handling treatments were evaluated in two experiments, the first of which compared four gear types with three handling treatments using a constant monthly frequency. The second experiment compared two similar gear types with the three handling treatments across four frequencies: seasonal, monthly, biweekly and weekly. Oysters were grown on a commercially developed lease in Grand Bay, Alabama. During a growing season of 147 days, oysters were subjected to monthly handling treatments that involved an emersion and handling treatment, a tumbling and handling treatment and a no handling, no tumbling treatment. End harvest oysters were evaluated based on time required to manually remove biofouling, shell metrics, and percent mortality.