Advancing Sustainable Aquaculture Production
The ARS aquaculture research program delivers new knowledge and technologies that improve domestic aquaculture production efficiency and product quality while minimizing impacts on natural resources. This work advances the efforts of more than 2,900 aquaculture farmers producing more than $1.5 billion worth of goods annually to meet the potential market demand generated by 300 million U.S. consumers. Aquaculture production is growing because demands for healthy seafood products are increasing even as stocks of wild-caught seafood are dwindling from overfishing and other stressors. Developing technologies that reduce production costs and maintain or improve product quality will help U.S. aquaculture producers meet that increasing demand. Ultimately, the ARS aquaculture research program will ensure that a healthy, competitive, and sustainable aquaculture sector is able to produce an abundant, safe, and affordable supply of seafood products. The following accomplishments highlight ARS FY 2019 advances in catfish, salmon, trout, and oyster production.
ARS advances blue catfish breeding
Blue catfish germplasm for release to U.S. catfish farmers. Over the last 15 years, U.S. catfish production has shifted from predominant use of purebred channel catfish to the production of F1 hybrids between channel catfish and blue catfish. ARS scientists in Stoneville, Mississippi, established the most diverse collection of blue catfish in existence and initiated evaluations of these strains for purebred blue catfish and hybrid catfish performance. Initial research revealed that purebred and hybrid progeny of the Rio Grande strain of blue catfish showed superior growth and meat yield relative to other blue catfish strains. Approximately 10,000 4 to 6-year-old Rio Grande fish, 20,000 2-year-old Rio Grandes, and 100,000 Rio Grande fingerlings will be released to farmers during fiscal 2020.
Blue catfish sperm cryopreservation. The F1 hybrid between the blue and channel catfish represents 75 percent of current U.S. farm-raised catfish production. However, the blue male catfish must be sacrificed to obtain sperm for use in hybrid production. ARS scientists in Stoneville, Mississippi, in cooperation with ARS scientists in Fort Collins, Colorado, and Louisiana State University, established a collection of cryopreserved blue catfish sperm. This collection is a crucial component of efforts to produce improved blue catfish germplasm for release to U.S. catfish farmers. Currently sperm from approximately 300 blue catfish males has been cryopreserved and is used for breeding.
Improved North American Atlantic salmon germplasm. Commercial salmon farming in the United States is expected to increase 5-fold over the next 3 years, and an Atlantic salmon breeding program is needed to support this industry expansion. ARS researchers in Franklin, Maine, developed a selection index in the St. John River strain of Atlantic salmon for carcass weight, fillet color, the conversion of α-linolenic acid into the omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), and resistance to sea lice. Eggs from the improved strain have been provided to industry stakeholders for integration and propagation on commercial farms. Development of salmon germplasm with increased growth, enhanced processing characteristics, and disease resistance will improve the production efficiency and sustainability of the U.S. salmon industry.
Superior ARS trout germplasm now used commercially. Most rainbow trout farmers do not manage their own broodstock, but instead purchase eggs for production from outside sources. The second largest commercial egg retailer (Riverence) in the United States obtained trout germplasm noted for growth and utilization of plant protein feed from ARS researchers in Aberdeen, Idaho, and is now selling eggs from these lines. The company is expressly marketing eggs from the ARS line as being hardier and has demonstrated their improved growth rate under different environmental conditions compared with eggs supplied by other vendors in the United States and abroad. In addition, the company is the second largest commercial producer of rainbow trout and uses ARS germplasm almost exclusively in its production farms.
The pathogen Yersinia ruckeri can sense its host. Disease-causing bacteria have evolved systems to recognize their hosts and respond by turning off functions that might trigger an immune response. ARS researchers in Leetown, West Virginia, demonstrated that the pathogen Yersinia ruckeri shuts off production of the flagellum when it senses its rainbow trout host. The flagellum is a whip-like structure that bacteria use for locomotion, but it also is a potent immune stimulator. By creating a mutant Yersinia ruckeri strain that cannot shut off flagellum expression, the researchers demonstrated that absence of the flagellum during infection is critical for the bacteria to avoid recognition and subsequent destruction by the fish’s immune system. This work provides a better understanding of the factors leading to infection and will guide development of new vaccines for disease control.