Evaluation of Elevated Rack Height to Control Biofouling on an Intertidal Oyster Farm: Efficacy and Economics

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Commodities

• Animals: shellfish

Practices

• Animal Production: aquaculture

Biofouling is an ever-present problem for shellfish farmers. Among the many biofouling agents are mud worms, genus Polydora.  Mud worms can cause significant economic loss on oyster farms. They can cause mortality, reduce growth, damage shells making them difficult to shuck, and cause internal shell blisters that reduce marketability. Strategies to control mud worm biofouling present significant labor costs and logistical challenges, limiting their application and utility. Preliminary studies on our intertidal farm suggest that increasing the height of our oyster bag racks might prove an effective strategy to control these pests; however, our simplistic trial lacked scientific rigor and failed to examine the potential tradeoffs such as reduced growth rates. This project will evaluate Polydora sp. biofouling on oysters maintained at a standard height of 15” and elevated heights of 25” and 30”. Labor inputs to clean the oysters at each treatment will be documented weekly through the summer season and production metrics (survival, growth, condition, disease) as well as the prevalence and intensity of mud worm blisters will be evaluated in the fall.  An economic analysis will be conducted to compare production costs and benefits of the three methods.

1. Evaluate the efficacy of elevated rack height in controlling biofouling of Polydora in oysters grown on a mid-Atlantic intertidal oyster farm
2. Evaluate the effect of rack height on survival, growth, disease, and condition of oysters grown on a mid-Atlantic intertidal oyster farm
3. Examine the economic costs and benefits of elevated rack height for the control of Polydora biofouling on a mid-Atlantic intertidal oyster farm
4. Share the results of this project with shellfish farming, extension, and research communities.