Louisiana Aquaculture Improvement through Science and Technology

Non-Technical Summary: Louisiana supports one of the most diverse aquaculture industries in the U.S. New technologies are needed to address the many concerns related to maintaining these viable industries within the state. Crawfish is the leading aquacultural species, but fall reproduction and survival rates are highly variable in female broodstock, trapping cost efficiencies are in constant need of improvement, pond inventory assessment methods are desperately needed, and the effect of recruitment class on crawfish yield and profitability needs to be better understood. Louisiana also leads the nation in alligator production, but rising energy costs are reducing profits and improved energy-use efficiency is needed. Although catfish production is declining within the state, development of new technology to stimulate advances in genetic improvement and disease prevention could spark a resurgence of this species. New and emerging species such as coppernose bluegill may offer alternatives to catfish production and development of new methods of cocaho minnow production could stimulate growth in the baitfish industry. Finally, ensuring the safety and quality of aquaculture food products must remain a priority. <P> Approach: Further development, refinement, and intensification of catfish broodstock conditioning, artificial spawning, ultrasound, and cryopreservation methods will be investigated with the goal of optimizing procedures for commercial-scale production of improved channel catfish and hybrid catfish. Recombinant DNA techniques will be used to adapt the Lambda Red Recombination System for use with Edwardsiella ictaluri. This will allow for rapid characterization of the role virulence factors play in E. ictaluri invasion. Juvenile coppernose bluegill will be stocked in replicated 0.08 ha ponds in winter at four densities ranging from 2,471 fish per ha (recommended recreational pond density) to 2.5 times this density. The goal is to determine the feeding rate/stock density combination that will produce 500g food fish in one year. Crawfish reproduction will be assessed in female broodstock obtained from ponds receiving short-term supplemental feeding compared with no feed. The ability of female broodstock to build energy reserves prior to burrowing as well as the timing and/or location of crawfish burrowing within a pond and their effects on survival and reproduction will be determined. Crawfish capture efficiency of various trap type by trap density combinations will be determined along with the effective attraction area of standard commercial crawfish baits (both fish and formulated) at various water temperatures. Various techniques and systematic sampling in crawfish ponds with known populations will be used to develop a means of determining crawfish pond inventory. To quantify the effects of secondary recruitment class on overall crawfish production, replicated pools will be assigned to one of four treatments where a primary recruitment treatment will be compared to the primary plus various secondary recruitment times on growth and yield. Outdoor tanks will be used as mesocosms for cocaho minnow spawning and grow-out under three different management systems each involving spawning and various staggered grow-out methods of fry to marketable size. Personal interviews with alligator farmers will provide initial data on current energy use, and energy balance and conservation measures will be employed. Research will be completed using crawfish chitosan to reduce catfish fillet off-flavor and improve refrigerated storage time. Additionally, research will be initiated to investigate the effects of chitosan coating on quality characteristics of frozen/thawed alligator meat. Finally, research will be initiated to monitor antimicrobial resistance patterns and screen for resistance genes in Vibrio spp. isolated from environmental and retail oysters.