UPDATE TO THE ATLANTIC SALMON BREEDING PROGRAM AT THE NATIONAL COLD WATER MARINE AQUACULTURE CENTER

The USDA-ARS National Cold Water Marine Aquaculture Center (NCWMAC) in Franklin, ME has been supporting the U.S. coldwater marine aquaculture industry for the past thirteen years by developing a genetically improved North American Atlantic salmon.  The St. John's River stock was chosen as the focal strain in the program because of fast growth, certification of North American origin, and widespread utilization by industry.  The objectives of our research program have been to: 1) develop a selection index for important traits such as carcass weight, cold tolerance, fillet color, fat content, and sea lice resistance, 2) evaluate and validate the usefulness of incorporating genomic information into the salmon breeding program, and 3) evaluate the usefulness of a lumpfish (Cyclopterus lumpus) selective breeding program.  

Our selected and unselected (control line) Atlantic salmon are evaluated with the assistance of industry partners in net pens to simulate commercial conditions.  We have observed an increase in growth by approximately 15% for each generation while survival has been similar between groups of fish.  Two of the most important traits for consumers are omega-3 fat content of the fillet and the color of the fillet.  We have observed that crude fat, as measured in the Norwegian prime cut (just behind the dorsal fin) ranges from 7 to 13% (wet weight) for all measured year classes.  Total omega-3 fatty acid content in families ranges from 5 to 15% of the total fat with an average of 12.8%.  The amount of EPA and DHA in a single portion of the fillet averaged 2-3 g, which is the industry standard.  Astaxanthin and canthaxanthin concentrations ranged from 1.1 to 4.1 μg/g of fillet.  Future year classes will be evaluated to assess progress in these two traits.

Selection for resistance to sea lice has been an important component of the breeding program since 2015. At that time evaluations of phenotypic family based resistance were standardized and conducted across all families in the breeding program. Currently evaluations are based on replicated small scale infections. Based on conservative models, the heritability seen across our populations is 0.20. In the fall of 2017, the first year class of families screened under the new program were spawned. The offspring of this spawning will be evaluated in 2019. In addition to the current challenged based screening, efforts are being made to develop genetic markers and tools to estimate the genetic breeding values.  Furthermore, a lumpfish selective breeding program has also been developed as a means to control sea lice infection.