National Program 106            Aquaculture

National Program Annual Report: FY 2006

• Introduction
• Genetic Improvement
• Integrated Aquatic Animal Health Management
• Reproduction and Early Development
• Growth, Development, and Nutrition
• Aquaculture Production Systems
• Sustainability and Environmental Compatibility of Aquaculture
• Quality, Safety, and Variety of Aquaculture Products for Consumers

Introduction

The aquaculture national program continues to receive strong support from stakeholders. The FY 2006 ARS appropriations included increases for aquaculture research conducted at five locations in three of the seven national program action plan component areas. Construction for the National Cold Water Marine Aquaculture Center, Franklin, Maine began in the fall, 2005 and moved close to completion. Construction funds were also included in the agency’s appropriations for the Hagerman Fish Culture Experiment Station, Hagerman, Idaho and the National Cold Water Marine Aquaculture Research Center, Orono, Maine,

The National Cold Water Marine Aquaculture Center in Franklin, ME completed 2 years of biannual fish health inspections in 2006 on all year classes of Atlantic salmon. The biannual inspections evaluated fish for ten different pathogens and none were detected. The research facility’s salmon stocks in the breeding program now have disease-free status and permits can be obtained from state, federal, and international sources for transfer of fish or eggs from the breeding program to other facilities.

ARS aquaculture scientists in Fairbanks Alaska participated in “ComFish” the largest show and exhibition for the commercial fishing industry in Alaska and “Changing Tides: Wild Alaska Salmon” showing potential new products from Alaska salmon byproducts

Scientists at the National Center for Cool and Cold Water Aquaculture at Leetown, West Virginia, were awarded $700,000 from the CSREES-NRI competitive research grants program for Animal Genomics. The award was given to Y. Palti, C. Rexroad III, R. Vallejo and M-C Luo (University of California-Davis) to complete a scaffold bacterial artificial chromosome (BAC) physical map for the rainbow trout genome and to integrate the physical map with the trout genetic linkage map.

Scientists at the Catfish Genetics Research Unit at Stoneville, Mississippi published the physical map for catfish, Ictalurus punctatus (www.ars.usda.gov/Main/docs.htm?docid=14234 ).

Several scientists in the national program received prestigious awards and recognition, and were appointed to leadership positions, including: 

Phil Klesius, Auburn, AL – Appointed as co-chair, Biologics Committee of the Joint Subcommittee on Aquaculture.

Brian Small, Stoneville, MS -- Early Research Scientist Award, Mid-South Area, USDA-ARS, and, Appointed to the 2007 Editorial Board for the Journal of Comparative Biochemistry and Physiology

Les Torrans, Stoneville, MS -- North American Journal of Aquaculture, Best Paper – Runner-Up

Dr. Chhorn Lim, Stoneville, MS, edited yet another book: “Tilapia: Biology, culture and nutrition” with collaborators.

The Fish Disease/Therapeutic Drug Approval research group at the Harry K. Dupree Stuttgart National Aquaculture Center received the Food and Drug Administration’s Leveraging Collaboration Award as a member of the Aquaculture Working Group/Drug Approval Coordination Workshop.

A world-wide animal health company is developing and licensing a Streptococcus agalactiae vaccine invented by scientists at the Aquatic Animal Health Research Unit at Auburn, AL. The vaccine will be protected by 25 foreign patents. Several vaccines are being commercialized that are health management tools for use in biosecurity and preventing the introduction of domestic and foreign disease agents into U.S. fish farms.

The national program welcomed three new scientists to its ranks during 2006, including:

Dr. Adam Fuller, Research Geneticist was selected to lead research on genetic improvement of hybrid striped bass at Stuttgart, AR.

Dr. Julie Bebak , DVM was selected to lead the epidemiology research on warm water fish pathogens at Auburn, AL.

Dr. Ted Wu, an environmental chemist, was hired as a postdoctoral fellow to work with Peter Bechtel on fishery byproducts at Fairbanks, AL.

The national program was highly prolific again in 2006, publishing widely in refereed journals and periodicals, and delivering a large number of invited presentations at local, national, and international conferences, meetings, and symposia.

The following sections of the report summarize high impact research results addressing the various components of the current national program action plan.

Genetic Improvement 

Since there has been limited genetic improvement of aquaculture stocks, major opportunities exist for improvement through traditional animal breeding, broodstock development, germplasm preservation, molecular genetics, and allied technologies.  ARS research addresses improvement of growth rates, feed efficiency, survival, disease resistance, fecundity, yield, and product quality; genetic characterization and gene mapping; and conservation and utilization.

Breeding catfish and rainbow trout to increase disease resistance. ARS scientists at the Catfish Genetic Research Unit, Stoneville, Mississippi and National Cool and Cold Water Aquaculture Center, Leetown, West Virginia discovered genetic components of resistance to Edwardsiella ictaluri in catfish and to Flavobacterium psychrophilum in rainbow trout. The high variation in breeding values for resistance to these two major diseases in these aquatic animals holds promise for breeding fish with greater resistance to these major diseases. Field evaluation is underway for an improved strain of catfish. The toll-like receptor gene is expressed at a lower level in resistant catfish and will be evaluated as a candidate for marker-assisted selection of catfish for survivability. Marker-assisted selection could improve the accuracy of selection for this elusive trait.

Progress toward developing a select line of North American Atlantic Salmon. ARS scientists at the National Cold Water Aquaculture Center, Orono, Maine, collected weight and mortality data on the five strains of salmon during the winter of 2006 on the 2003/2004 year-class stocked in industry collaborator sea cages. Growth and mortality varied widely indicating an opportunity to develop a select strain. The fish will be cultured to market size, harvested in winter of 2006, data analyzed, and broodstock spawned for a select line.

Gene discovery in rainbow trout and channel catfish.  ARS scientists at the National Center for Cool and Cold Water Aquaculture and the Catfish Genetics Research Unit discovered several genes and gene products that may have potential for use as biomarkers. The toll-like receptor gene of catfish is strongly expressed in response to the catfish disease enteric septicemia, and two new chemokine genes and three new toll-like receptor genes were identified and mapped in rainbow trout. Other genes identified include trout uncoupling protein genes, trout leptin, trout MHC genes, and the catfish ghrelin gene. Knowledge of these gene functions and products may enhance the accuracy and reduce the time needed to develop select strains of fish for culture.

Genetic map constructed for rainbow trout. A genetic linkage map for rainbow trout composed of over 1000 microsatellite DNA markers was constructed and analytical methods were designed for analyzing mapping data of outbred crosses of rainbow trout by ARS scientists at the National Center for Cool and Cold Water Aquaculture, Leetown, West Virginia. These data will be useful for identifying genes that affect traits of interest in aquaculture production efficiency.

Integrated Aquatic Animal Heath Management

Despite progress in aquatic animal health, significant losses to diseases still occur.  ARS research addresses improvement of survival, growth, vigor, and well-being of cultivated aquatic animal stocks through integrated aquatic animal health research, improved technologies and practices such as population health management; and development of health management products, including vaccines and therapeutics, and disease detection/diagnostic techniques.

New vaccines developed to protect fish from Streptococcal diseases. ARS scientists at the Aquatic Animal Health Research Unit, Auburn, Alabama developed novel vaccines to control the bacterial pathogens, Streptococcus agalactiae and Streptococcus iniae in fish. S. agalactiae and S. iniae have been associated with significant mortalities among a number of freshwater, estuarine, and marine species. Streptococcal disease results in more than $100 million in losses annually in cultured fish. Immunization is estimated to profit the farmer by $100 to $300 more per acre because fish eat more feed, grow faster and suffer less mortality. A major pharmaceutical manufacturer is cooperating by a Cooperative Research and Development Agreement to commercialize these vaccines for a world-wide market.

A rapid low-cost test developed for simultaneous and accurate identification of three pathogens. Traditional diagnosis requires about a week to arrive at a definitive identification by which time the opportunity to treat or salvage uninfected stock has passed. ARS scientists at the Aquatic Animal Health Research Unit, Auburn, Alabama developed a multiplex-polymerase chain reaction technique to enable simultaneous and accurate identification of Edwardsiella ictaluri (ESC), Flavobacterium columnare (columnaris disease), and Aeromonas Hydrophila, (motile aeromonad septicemia). This test will enable fish farmers to identify the presence of these pathogens within several hours of observing signs of disease or mortalities to make management decisions to avert the spread of disease.

Florfenicol is efficacious against Streptococcus iniae infection of hybrid striped bass.  Streptococcus iniae is a major pathogen of hybrid striped bass aquaculture. There are no efficacious vaccines available. ARS scientists at the Harry K. Dupree Stuttgart National Aquaculture Research Center, Stuttgart, Arkansas demonstrated that florfenicol increased survival of infected striped bass from 4 to 94%. This research provides data needed for future FDA-approval of florfenicol to treat hybrid striped bass infected with S. iniae.

Reproduction and Early Development

Reproduction and early development are important aspects of species domestication and sustainability.  ARS research on this component interacts with several of the other components of the Aquaculture National Program.  The selection below exemplifies the multi-disciplinary character of husbandry research.

Catfish survival improved in hatcheries. Mortality of catfish eggs and fry in commercial hatcheries ranges from 10 to 30% of eggs brought to the hatchery based upon data collected at twenty commercial hatcheries. ARS scientists at the Catfish Genetics Research Unit, Stoneville, MS and collaborators at Mississippi State University Extension Service determined oxygen requirements of catfish eggs and fry from the current management practices of the twenty hatcheries. Recommendations were developed for hatchery managers and are now in use that could result in a 10-20% increase in fry production by the catfish industry.

Revised pond fertilization recommendation improves catfish fry production.   Nursery pond fertilization is an important practice among many species of fish to enhance production of phytoplankton and zooplankton needed for development of fry into healthy fingerlings. ARS partners at the Mississippi Agricultural and Forestry Experiment Station, Stoneville, Mississippi evaluated current practices and found ponds are nitrogen limited and not phosphorus limited as previously believed. New fertilization recommendations being developed from this research are being quickly adopted by catfish farmers for more consistent and economical fry production.

Growth, Development, and Nutrition

There are substantial opportunities to improve the growth, development, and nutrition of cultivated aquatic organisms.  ARS research addresses improving survival, growth rates, feed conversion, environmental tolerances, and feed formulations and feeding strategies to reduce dependence on marine fish-based protein in aquaculture diets.

Salmon liver as a source of cholesterol. Salmon byproducts including livers are not utilized for human food and are often discarded. ARS scientists in Fairbanks, Alaska in collaboration with scientists at the University of Alaska, Fairbanks have developed industrial scale methods for processing livers into meal. Liver meal contains a high content of cholesterol, an important essential nutrient for shrimp and possibly another aquaculture species in early stages of development.   

Aquaculture Production Systems

There are opportunities to improve the performance of aquaculture production systems through development and application of innovative engineering approaches and technologies.  ARS research addresses development and successful application to aquaculture of new technologies as well as relevant existing technologies and engineering presently employed in other sectors of the economy.

Application of behavior to handling fish.  Handling and moving of fish is stressful to the fish and results in injuries and mortalities. ARS partners at the Conservation Fund Freshwater Institute, Shepherdstown, West Virginia developed technology based upon rainbow trout’s ability to sense and avoid carbon dioxide dissolved at elevated levels in water to move rainbow trout from tank to tank for management purposes or harvesting. This technique is inexpensive, safe, and humane for transferring fish in circular aquaculture tanks.

Quality, Safety, and Variety of Aquaculture Products for Consumers

 The overall goal of ARS research in this area is to improve the quality, safety, and variety of aquaculture products through research and technology transfer.  ARS research addresses improvement of the safety, freshness, flavor, texture, taste, nutritional characteristics, and shelf life of cultivated fish and shellfish, and development of new and improved value-added products and processes.

Feeding fish oil to catfish increase Highly Unsaturated Fatty Acids (HUFA) in fillets. HUFA have obtained a positive reputation in the medical and human nutrition communities for being healthful. ARS scientists at the Aquatic Animal Health research Unit, Auburn, Alabama demonstrated that marine fish oil added to diets were proportionately reflected in HUFA of catfish fillets. The levels of fish oil studied had little influence on performance of catfish. This research may be useful as a marketing tool for catfish which is not known for being a high source of HUFA.