Background


Oysters and other bivalve mollusks are sessile and unable to escape harm. They have evolved over millions of years to endure most of nature’s fickle wrath but wild bottom harvest is no longer a commercially viable in some of the most productive areas of the Gulf and Atlantic US Coasts. Commercial oyster production has largely shifted to off bottom containerized oyster culture.   Off-bottom containerized production techniques have resulted in a resurgence of the oyster industry along the US Atlantic seaboard over the past couple of decades. Similar techniques are being successfully introduced to the Gulf of Mexico where oysters typically reach market size faster because of the extended growing season. Off-bottom containerized oyster production accelerates growth to market size, reduces biofouling and produces more uniform and shapely oysters that are more desirable and valuable to the half-shell market. However, similar to wild harvest, containerized oyster culture suffers from all of the common human health hazards such as pathogens, biotoxins and other chemical contaminants that can result in costly area closures and even more disruptive recalls in the event of illness outbreaks. In addition, containerized oyster culture is subject to even greater risk than bottom culture from extreme climate events such as hurricanes that damage or destroy gear and these costs typically exceeds those from crop losses. Given the high investment costs and the plethora of potential hazards to human health, crop loss and gear destruction, it is critical for industry resilience to develop best management practices from farm to fork.
While a number of containerized aquaculture systems are being used in the US, most of the gear is produced overseas in countries like Australia and Canada, which adds significant costs and time to ship and import. Much of the current gear has small capacity of 100-1000 shellfish and is limited to use in intertidal areas or a relatively narrow range of water depths (3-5’) to accommodate production practices typically accomplished by wading or in low wave energy areas for working from boats. Current oyster culture systems require manual labor to raise and lower shellfish in and out of the sea for operations including desiccation, density reduction, harvest or relocation. Shellevator automation reduces manual labor that is a major cost of oyster culture and exposes workers to a plethora of hazards. Dependence on manual labor also limits the scale of the culture system and bandwidth of operation to wading depths in most cases. Shellevators can be operated from piers or vessels and operators avoid entry into the seawater and exposure to harmful pathogens, venomous animal, hypothermia, drowning and other hazards. Shellevators can be constructed to the size existing ships providing additional economy of scale by reducing the number of unit manipulations. Existing shelllevator prototypes are an order of magnitude (>10,000 market-size oysters) larger than the largest existing oyster culture system units.  Automation and scale greatly reduce crisis response time such as a rapid or sudden turn of a hurricane and prevent loss of crop or equipment. Hurricanes Florence and Michael resulted in losses of $10,000,000 and $20,000,000 in North Carolina and Florida, respectively. Manifold valves can be easily opened in seconds to sink shellevators to the seafloor below the high energy of surface waves and debris fields during tidal surges usually without location to more protected waters. Normal boat anchors can hold shellevators in place and allow 360-degree rotation.