Brief Summary of Minutes of Annual Meeting

The state of the catfish industry was discussed, and the increasing role of hybrid catfish in the industry. The growth of adoption of hybrid culture and processing was discussed. The membership expressed a desire to continue the project for another 5 years. Potential objectives and research problems identified included developing farm plans and staggered stocking to allow year round supplies of single batch hybrids, optimizing hatching conditions, improving egg quality, nutrition for brood stock and food fish hybrids, genetic improvement of hybrids, hormone induced maturation, optimizing fingerling production systems and thermal stress tolerance to guide genotype selection of hybrids with the advent of global warming.

1. Improve hybrid embryo production by determining the best nutritional regime to maximize fecundity and hatch rate from induced channel catfish females and blue catfish males- Lipids and fatty acids have been reported to play a major role in brood stock nutrition and influence the quality of developing eggs. Pond trials conducted showed that catfish oil incorporated as a dietary lipid supplement improved the oocyte fatty acid profile and subsequent reproductive performance of channel catfish. At 5% catfish oil supplementation to the brood fish diet, a higher percent of catfish females attained a threshold level of maturity suitable for hormone induced spawning, ovulating response, fecundity and hybrid embryo production. 2. Conduct family selection for fecundity, hatch rate of hybrid embryos and hybrid fry produced/kg for channel catfish females that were hormone induced and hand stripped- Second generation channel catfish females selected for increased hybrid fry production when hand stripped of their eggs were spawned and data collected on fecundity, hatching rate and fry produced per kg of female body weight. Currently, data is being analyzed. 3. Lengthen the short spawning season for hybrids by developing and identifying early, peak and late spawning lines of channel catfish. Peak and late spawning lines were spawned at cold temperatures. Data is being analyzed. This experiment may have been compromised by the unusual early warming of air and water temperatures. 4. Determine the relative importance of stocking density of channel catfish females for hybrid embryo production- should density be based on surface acreage or volume? No experimentation was conducted on this project during 2011. Although previously identified as a priority by farmers, a committee partially composed of catfish farmers rejected funding a project to address this objective. 5. Compare various forms of LHRH implants to address INAD concerns and reduce implant costs- Synchronizing ovulation of channel catfish females and subsequent production of good quality eggs has been a major obstacle in producing commercial quantities of channel X blue F1 hybrid fry. Carbopol and cholesterol implants sustained release of LHRHa, synchronized maturation and improved ovulation of channel catfish compared to LHRHa suspension. Improved maturation of ovulated eggs also resulted in higher hatching success of hybrid embryos. Future studies will address the endocrinological response of implants on egg quality. Cellulose acetate based LHRHa implants were highly effective resulting in approximately 90% ovulation, while saline, sham implanted controls failed to ovulate. Toxicity studies were also conducted, and the data is currently being analyzed. 6. Determine the ideal temperature for ovulation hybrid embryo hatching in best late, peak and early spawning strains. This objective was not addressed during 2011. 7. Improve hybrid embryo production via pheromonal manipulation of channel catfish males and blue catfish males for improved ovulation, spermiation, egg quality, hatch and fry production- Catfish spawning rituals for channel x channel, blue x blue and channel x blue when hormone stimulated to spawn naturally in aquaria were compared. Pairs of fish were continuously videotaped for more than 48 h and the tapes reviewed for specific types of behavior. Similar behavior patterns were observed with all crosses. No unique behaviors were observed that were specific to channel x channel or blue x blue pairs. Spawning success was ch x ch, 75%. bl x bl, 40%, and 61.5% for ch x bl in 2010 but were 52.5%, 23.1% and 18.5% in 2011. Egg yields were 6,850, 2,910 and 5,444 eggs/kg female for the respective crosses in 2011 and 8,155, 10,122, and 3000/kg in 2011. 8. Develop extended refrigerated storage and cryopreservation of sperm.This objective was not addressed during 2011. 9. Evaluate morphological changes of oocytes during oocyte maturation in female catfish and relate this to fertilization, development and hatch- This objective was not addressed during 2011. 10. Conduct recurrent family selection for growth, feed conversion, disease resistance, oxygen tolerance , harvestability and carcass traits of hybrid catfish- Hybrids resulting from recurrent selection have been produced, and are now being evaluated. 11. Develop in pond seining/grading technology specific for hybrid catfish to prevent gilling- This objective was not addressed during 2011. 12. Develop technology to ejaculate blue catfish- This objective was not addressed during 2011. 13. Conduct gene transfer to improve growth, feed conversion, disease resistance and body composition and transgenic sterilization of hybrid catfish- Channel catfish and blue catfish cell cultures were established from testes of fingerlings.Tentative classification of the cell types was made. Cell counting procedures were established and improved. Fuller's earth and bromelain (pineapple enzyme) were compared for their ability to prevent adhesiveness of the eggs prior to introduction into the pressure chamber. Bromelain was used shortly post fertilization to fragment the egg mass and separate the eggs, while the Fuller's earth was used concurrently with the activation step of dry fertilization. Both de-adhesion techniques showed promise, and hatch rates were encouraging. The Bromelain was successful at fragmenting a large egg mass into smaller clumps. However, separation into individual eggs was difficult. Also, Bromelain if not used correctly will cause the eggs to totally digest due to the proteolytic nature of the enzyme. Fuller's earth was easier to use and more effective in individual egg separation. It was also safer as dosage does not need to precise, and accidentally over treating the eggs will not lead to mortality. Additionally, handing stress is reduced as de-adhesion, fertilization, and activation is done in one step. Fresh, cultured and cryopreserved putative stem cells from blue catfish were introduced to triploid channel catfish via microinjection and electroporation. Techniques were developed for mass injection of embryos while allowing for high survival rates, and several hundreds of putative xenogenic embryos were produced. Several normal triploid channel catfish males were mated with diploid channel catfish females. Despite being small these males exhibited normal courtship, and were able to induce the females to ovulate and deposit eggs. Gene constructs coding for shRNAi to disrupt primordial germ cell mighration were introduced into channel catfish. Preliminary results indicate that this approach is effective in sterilizing the catfish. During the coming year objectives 1,2,3,5, 10 and 13 will be addressed. Milestones 1 nutrition, 5 effective LHRHa implants and 13 transgenic sterilization have been achieved, but can be improved further. Resources are not available for objectives 4 and 6. Milestone 7 was addressed in an earlier year, and pheromones were identified that attract male blue catfish to channel catfish females, and that appeared to enhance ovulation. Researchers addressing this area are retiring, and this objective/milestone should be addressed in a follow on project. Milestone 8 has been achieved, and efficient refrigeration and cryopreservation of blue catfish sperm is achievable. Milestone 9 has been achieved and oocyte maturation can be effectively determined, but is not commercially practical because of the slowness in the evaluation technique. Milestone 11 has been achieved, and extremely effective harvesting technology for hybrids is now possible and is being implemented in the catfish industry. No positive results have been obtained for objective 12.

Arguello, R. 2011. Satiation feed consumption as an inventory tool to assess biomass of channel X blue hybrid catfish in earthen ponds. Master's of Science thesis, Auburn University. Arguello, R. and Phelps, R.P. 2011. Satiation feed consumption by hybrid catfish as a function of body weight and water temperature. Electronic conference proceedings (abstract), World Aquaculture Society Meeting, New Orleans LA. Chatakondi,N.G., R. D. Yant, A. Kristanto, G. M. Umali-Maceina and R. A. Dunham. 2011. The effect of LHRHa (luteinizing hormone releasing hormone analog) regime and stage of gonadal maturity for induced ovulation of channel catfish, Ictalurus punctatus.Journal of the World Aquaculture Society.42: 845-853 Duncan, J. and Phelps, R.P. 2011. Spawning characteristics of blue, channel, and channel x blue catfish when hormone-induced and allowed to spawn naturally. Electronic conference proceedings (abstract), World Aquaculture Society Meeting, New Orleans LA.