1a. Objectives (from AD-416):
1: Define phenotypic measures and estimate genetic and phenotypic parameters for commercially important traits such as growth, cold tolerance, fillet color, and fat content in Atlantic salmon. • 1A. Define phenotypic measures and estimate genetic parameters for growth (carcass weight), fillet color, and fillet fat content in Atlantic salmon. • 1B. Define phenotypic measures and estimate genetic parameters for cold tolerance in Atlantic salmon. 2: Develop a multi-trait selection index to produce and release Atlantic salmon germplasm selected for multiple traits.
1b. Approach (from AD-416):
The research program supports the coldwater aquaculture industry with a breeding program developing improved lines of North American Atlantic salmon. Atlantic salmon cultured in research objectives in the breeding program is based on life stage and separation of year classes. An incubation system will be used for eggs and newly hatched fry before first feeding, parr tanks are used for first feeding fry to 30-40 g salmon, smolt tanks are for 30-40 g to 100 g pit tagged salmon, on-grow tanks are for 100 g to 1.0 kg salmon in their second year, 3-yr old broodstock tanks are for 1.0 kg to 3.0 kg salmon, and one 4-yr old broodstock tank is for growing salmon to 3.0 kg to 6.0 kg until spawning. Up to 224 families of Atlantic salmon with 300-500 eggs/family will be cultured each year. Approximately 250 eggs will be saved from each family mating and raised through parr size. Typically 30-40 smolts per family will be saved as nucleus of fish for the breeding program and cultured in biosecure tanks will become broodfish. Additional 30-40 smolts per family will be cultured and transferred to an industry collaborator for stocking into net pens for performance evaluations. Net pen fish will be cultured to market size, harvested from sea cages, and transported to a commercial processing plant. Data will be collected for carcass weight, sex, and stage of sexual maturity. Muscle tissue samples will be collected from each fish for fat and pigment analyses. A separate group of fish from each family will be pit tagged as smolts, cultured to 2-year old sub-marketable size and stocked into replicated fish culture tanks equipped filled with filtered, UV-treated seawater in a recirculation biofilter system. The water temperature will be lowered approximately 1C per day using a glycol-based chiller system capable of chilling seawater temperatures down to approximately -2C. Individual fish will be scored on the basis of temperature and time to loss of equilibrium and death and survival. Data will be analyzed to calculate phenotypic and genetic variation for carcass weight, fillet color, fillet fat, and cold tolerance traits. Heritabilities, breeding values, and genetic correlations for carcass weight, fillet fat, fillet color, and temperature tolerance obtained from performance data will be used to develop a selection index or index of merit for each individual broodfish chosen for spawning in a selected line. Selection of 4 year old fish for spawning will occur when fish are moved from 3-yr old broodstock tanks into the 4-yr brood stock system prior to the spawning season. Relative economic weights for each trait will be determined in consultation with industry collaborators and account for the market value of each trait. Germplasm from an Atlantic salmon line selected for multiple traits will be released to commercial producers and consumers.
3. Progress Report:
Pedigreed families were produced by spawning broodstock selected for improved carcass weight from the 2008 year class of salmon already in the National Cold Water Marine Aquaculture Center's (NCWMAC) breeding program. Fish from the 2008 year class were cultured in marine net pens in collaboration with industry, and growth data were analyzed to obtain estimated breeding values on broodfish to be spawned as a line selected for increased carcass weight. The NCWMAC transferred approximately 500,000 unfertilized and/or eyed eggs from the USDA ARS NCWMAC’s Atlantic salmon breeding program to the Maine Aquaculture Association (MAA). The germplasm originated from St. John’s River stock and was named “USDA NCWMAC 2012 Year Class Atlantic Salmon Select Line”. Fish from the 2009 year class were cultured in marine net pens in collaboration with industry, fish were harvested and growth data analyzed to obtain estimated breeding values on broodfish to be spawned as a line selected for increased carcass weight. The mean carcass weight for 2009 year class St. John’s stock fish from the NCWMAC breeding program was 5.8 kg compared to a mean carcass weight of 4.8 kg for industry fish cultured under the same conditions. NCWMAC fish were 20.8% larger than industry fish and 85% larger than wild Penobscot River fish (3.1 kg) used as a control line. Data will be used to calculate breeding values on captive sibling adult broodfish and a line of St. John’s River fish will be selected using an index for multiple traits (carcass weight, fillet color, fillet fat, and sea lice resistance) in the fall of 2013 following discussions with industry collaborators. Broodfish were genotyped for North American origin using a panel of microsatellite loci and were health certified for specific pathogen free status following New England Salmonid Fish Health Guidelines and Canada’s Federal Department of Fisheries and Oceans Fish Health Protection Regulations (FHPR). The MAA distributed the germplasm to private industry under the direction of its stakeholder committee. The NCWMAC and MAA held a meeting with industry representatives to discuss technology transfer and review guidelines developed by the MAA Germplasm Committee to manage the technology transfer within the scope of this Agreement. Eyed eggs from the 2012 year class were disinfected and incubated in separate hatching trays. Fry were transferred to separate rearing tanks prior to first feeding and are being raised to parr size. When the fish reach 20-40 grams, individual fish will be pit tagged and cultured communally before being stocked into sea cages for performance evaluations and some fish will also be exposed to superchill temperatures for evaluation of cold tolerance. Research progress is consistent with the objectives of the project plan with the goal of improving performance of Atlantic salmon and releasing germplasm to commercial production.
1. Atlantic salmon evaluated and selected for multiple traits. Commercial salmon producers in the U.S. predominantly utilize stocks that are not many generations removed from wild, unselected stocks, and are legally required to culture certified stocks of North American salmon. ARS researchers at Franklin, Maine evaluated the growth of salmon from their breeding program in commercial sea cages in collaboration with industry. A salmon line was selected for increased growth, fillet color, and sea lice resistance using a selection index. Utilization of improved germplasm will increase the profitability and sustainability of coldwater marine aquaculture in the U.S. and provide a quality seafood product to U.S. consumers.
2. Arctic charr germplasm selected for increased growth and late maturity. Arctic charr have a flavor many consumers feel is superior to trout and salmon, however, expansion of arctic charr culture has not been rapid because of production problems related to slow growth and too early sexual maturity. Results from the charr breeding program have shown increased weight gain and reduced sexual maturity in one generation of selection. ARS researchers at Franklin, Maine released germplasm from this select line through a Coopertive Research and Development Agreement (CRADA) to a commercial producer.
3. Salmon growth in freshwater and seawater on fishmeal and marine-free diets. Atlantic salmon producers require knowledge about optimum salinity and feed formulations to lower production costs. Salmon were cultured by ARS researchers at Franklin, Maine in either freshwater or seawater on a standard fish meal or marine-free diet. Water source had no effect on growth, but fillet color was higher for fish grown in seawater and salmon fed the marine-free diet had lower omega-3 fatty acids compared to the fish fed the fishmeal diet. Atlantic salmon can be successfully cultured in a wide range of salinities, but proper diet formulation is needed to insure product quality.
Anttila, K., Dhillon, R., Boulding, E., Farrell, A., Glebe, B., Elliott, J., Wolters, W.R., Schulte, P. 2013. Variation in temperature tolerance among families of Atlantic salmon (Salmo salar L.) is associated with hypoxia tolerance, ventricle size and myoglobin level. Experimental Biology. 216: 1183-1190.