SBIR-STTR Award

Catfish production, 300 million kg annually, is 70% of all U.S. aquaculture production. In many impoverished areas of the South, this industry is critical for the economic viability of communities. Imports of fish products resulted in a $10.7 billion trade deficit in 2000. Imported catfish now threaten profits of catfish farms. Impediments to sustainability and competitiveness such as, slow growth, inefficient feed conversion, mortality from disease and the associated use of chemicals, loss of fish from low oxygen, inefficient harvesting, inefficient use of land space and processing waste can be diminished by utilization of the channel X blue catfish hybrid. This hybrid exhibits increased growth (20-100%), feed conversion efficiency (10-20%), disease resistance and survival (10-50%), tolerance of low dissolved oxygen (50-100%), harvestability (100%), book-and-line vulnerability (100%) and carcass yield (10%). This hybrid would revolutionize catfish production, but behavioral reproductive isolating mechanisms prevent consistent large-scale production of this hybrid despite large demand. Recent research indicates induced spawning with LHRH, brood stock nutrition and controlling fungus in the hatchery may be the keys to successful hand stripping for production of hybrid embryos. The efficiency of hybrid embryo production needs to increase to a competitive level by identifying the most economic technology to increase hatch of eggs. Objectives are to determine the seasonal variation of dosages of LHRH needed to efficiently induce females, determine proper nutritional preparation of brood stock and determine the best treatments to control fungus. Results from treatment variables will be compared economically to determine the direction of Phase II research to solve this problem.

Anticipated Results/Potential Commercial Applications of Research:
The anticipated result is that hybrid embryo production will be increased to the extent that large scale commercial adoption of this hybrid will occur resulting in a revolutionary advance in sustainability and profitability in the catfish industry which is now almost entirely based on the culture of channel catfish. Even in a dynamic, commercial environment, the adoption of hybrids can have huge impacts, through cost efficiency, premium selling prices, i.e., enhancing sustainability and profitability and providing sustainable, economic community development. The adoption of the hybrid will not only benefit large farms, but also aid small farms with alternative enterprise income, reduce chemical use and be environmental friendly. Use of this reproductively limited hybrid could better protect natural genetic resources.

Catfish imports are coming from third world nations capable of producing catfish and selling lower prices than American counterparts. Therefore, methods that improve efficiency and reduce the cost of producing catfish would be a tremendous asset to the industry. The hybrid catfish between channel catfish female and blue catfish males has been shown to have many superior characteristics compared to channel catfish, the species which accounts for virtually all catfish culture in the US. The most reliable method to produce hybrid catfish is by hormonal induction of channel catfish for ovulation, hand stripping of eggs, and artificial fertilization with blue catfish sperm, and hatching in troughs. Limited fry production is a major impediment for large-scale adoption of the hybrid catfish fry production. Research on the hybrid catfish production will focus to optimize LHRHa dosages based on gonadal maturity of female catfish, develop techniques to determine egg quality, optimize antifungal formalin treatments and to determine proper nutritional preparation of broodstock to further optimize hybrid fry production. Economic analyses on the risk of producing the hybrid fry based on best treatments would be compared with the traditional method of channel catfish fry production. OBJECTIVES: Superior performance of channel catfish, Ictalurus punctatus,(female) x blue catfish, I. Furcatus,(male)has been demonstrated in research and commercial ponds relative to the commonly grown channel catfish. The lack of reliable production technologies for hybrid catfish fry is preventing the expanded use of this cultivar. Specific objectives are to 1) develop procedures to determine and predict egg quality to allow optimization of LHRHa dosages based on the gonadal maturity of individual female channel catfish and maximization of hatch rate. 2) determine and develop predictors of egg and embryo quality that result in maximum hatch. 3) Optimize fungal control on hybrid embryos by determining optimal frequency of application of formalin. 4) identify the protein requirement of channel catfish females and blue catfish males resulting in maximum hybrid fry output. 5)assess economic performance and evaluate risks associated with commercial production of hybrid embryo, fingerling and food fish production. APPROACH: To improve the commercial production of channel x blue hybrid catfish will be addressed by the following objectives : Objective 1) Development of procedures to determine and predict egg quality to allow optimization and to allow optimization of LHRHa dosages based on the gonadal maturity of individual female catfish to maximization of hatch rate. Ovulation rate, fecundity, hatch rate and fry per kg of female weight will be determined for each female and treatment. The relationship of gonadal maturity, and steroid hormone profile will be determined to relate the rise and then decline of steroid hormone levels to the development and maintenance of egg quality and then the decline of egg quality late in the season. Progression of egg development, egg quality, hatch, temperature degree days and hormone profiles will be determined and correlated. Objective 2) To determine and develop predictors of egg and embryo quality that result in maximum hatch: Ovulated eggs from individual females will be scored for quality based on color, shape, texture, clumpiness, flow of eggs and conductivity of ovarian fluid. Percent fertilization, hatch rate and fry per kg of female ovulated will be evaluated for each treatment and compared over the season. Egg quality, embryo quality, fertilization, hatch and fry/kg female body weight will be correlated. Objective 3) to optimize fungal control on hybrid embryos by determining optimal frequency of application of formalin. Percent fertilization, percent hatch and fry/kg of female body weight will be determined for each treatment. Percent increase in fungal infection rates and percent increase in hatch of embryos would be calculated for each treatment assessed in the replicate tanks. Another experiment will evaluate withholding antifungal treatments during the critical stage of hybrid embryo development between 36-42 hours after fertilization at 28 C. Formalin treatment will be withheld for 0, 2, 4 or 6 hours (beginning at 36 hours) during the critical period. Percent fertilization and percent hatch will be calculated and compared. Objective 4) to identify the protein requirement of channel catfish females and blue catfish males resulting in maximum hybrid fry output will be evaluated. Post-spawning feeding regime on growth will be assessed in a 3 X 3 factorial design to evaluate reproductive performance, gonadosomatic index of males, ovulating rate, fecundity, hatch rate and fry/kg of female will be determined. Objective 5) Economic performance will be assessed for spawning methods, egg treatments, fry, fingerling and food fish production phases for years 2002 - 2004. For each production phase, data for hybrid production costs and economic returns analyzed using simulation and sensitivity analyses to test if the hybrid catfish weathers production risks and market uncertainties in comparison to channel catfish