Soft shell blue crab (Callinectes sapidus) aquaculture is one of the oldest domestic aquaculture industries along the East and Gulf Coasts of the United States. Soft shell blue crabs are produced by culturing pre-molt (peeler) crabs in shallow dockside or land-based shedding systems (floats or tables) until they shed their hard shell in order to grow. The production of soft shell crab in Louisiana, and across the United States, has declined over the past decade. In Louisiana, the number of soft shell crab producers has decreased from 300 individuals in the 1990's to less than 40 individuals today. The decline in producers has been attributed to hurricanes and storm damage, as well as an aging workforce in the industry. Our efforts have combined extension and outreach with lab-based bioassays to increase resiliency of the industry.
To help new soft shell producers and increase success for those still in the industry, we have worked to capture the institutional knowledge of existing shedders and update best management practices. We have developed outreach materials (i.e, factsheets and videos) summarizing key information on how to produce soft shell crabs. Information provided includes the basics such as the costs to get started, the basic system design, and the overview of crab shedding; and more advanced topics covering water quality and diseases, the major attributors to large mortality events in shedding systems.
High mortality in shedding systems has always been a problem for the industry, and diseases, such as Callinectes sapidus reovirus 1 (CsRV1), can play a significant role. The prevalence of CsRV1 in dead peeler crabs ranges from 22 - 75% in blue crab shedding facilities located in Maryland, Virginia, and Louisiana. We have conducted experiments focusing on the transmission of CsRV1 among crabs in shedding systems using scaled recirculating aquaculture systems. We have examined virus threshold transmission, waterborne transmission, and the impact of salinity on transmission. All transmission studies have relied upon Real time qPCR (RT-qpcr) for detection of CsRV. Preliminary data have shown that virus transmission is spread through water and is lethal to a crab within 2-3 weeks.