Research Project: Production of Sterile Atlantic Salmon

Location: National Cold Water Marine Aquaculture Center

Project Number: 8030-31000-005-054-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Oct 1, 2023
End Date: Sep 30, 2024

Objective:
The reliance on imported seafood to fulfill high quality protein needs of the United States reveals a vulnerable link in food security. The United States is a major consumer of seafood with Atlantic salmon making up the majority of fish consumed at approximately 420,000 metric tons per year which is 1.3 kg per capita consumption but, 95% of that is imported, contributing $3.4 billion annually to our trade deficit (FAO, 2020; Naylor et al., 2021). To maximize domestic seafood production there is a need for the development of sterile Atlantic salmon broodstock which produce sterile offspring to be used in both net pen and land-based aquaculture system. The Cooperator, Center for Aquaculture Technologies (CAT), offers a new method to produce sterile salmon using CRISP/cas9 technology. ARS maintains a selective breeding program in Franklin, ME and has expertise in raising and growing Atlantic salmon. New gene editing methods are currently being explored, with the aim to create populations of farmed sterile fish (Zohar, 1989). While multiple studies are utilizing gene editing to produce sterile fish, these methods cannot be upscaled for commercial applications in Atlantic salmon farming. Gene edited sterile fish appear to be an industry ideal. These fish wouldn’t divert energy into reproduction, or breed with wild fish, eliminating biocontainment concerns. However, those benefits would only last a generation and sterile fish cannot produce the next generation. In response to this conundrum, a collaboration has been formed with NCWMAC, National Cool and Cold Water Aquaculture Research, University of Maine’s Aquaculture Research Institute (ARI) and the Center for Aquatic Technology (CAT) to utilize the novel approach of CRISPR/cas9 gene editing in a novel way and solve the ultimate paradox ‘The Sterile/Fertile Broodstock’ for Atlantic salmon aquaculture. A new method combing gene editing (CRISPR/cas9) technology and germ cell (eggs and sperm) transplantation will support the mass production of sterile progeny suitable for use in commercial aquaculture facilities. The results will be increased domestic production and availability of healthy, sustainable seafood.

Approach:
The first step starts with a population of all female gene edited fish which have been further gene-edited so they produce sterile offspring. These gene edited traits require two copies of the modified gene, to result in sterility. The next generation would either have one copy of the modified gene and be used in a breeding population or have two copies of the gene, exhibit sterility and utilized for food production. The commercial-scale production of sterile production fish begins through the transplantation of germline cells from one gene edited broodstock donor into hundreds of other sterile broodstock. This multiplication leads to mass production of sterile progeny. Step 1: Compile Atlantic salmon genomic data to identify salmon gene sequences for conserved genes to be targeted to create sterility solutions. Design and produce molecular reagents for gene targeting based on Atlantic salmon genome. Step 2: Set up space for microinjection of salmon eggs. Provide access to salmon eggs and fertilized embryos for research use. Set up mobile laboratory, and train NCWMAC staff in microinjection techniques for GE and Germ Cell Transfer (GCT). Advise on laboratory set up for future GE and GCT work. Step 3: Microinject salmon embryos to create sterility and performance lines, and to create recipient lines for GCT. Optimize protocols for microinjection. Step 4: Hatch research embryos and evaluate survival and pigmentation. Step 5: Continue to raise research animals. Collect performance data. Collect sterility data. Collect tissue samples for analysis of GE effectiveness. Send samples to San Diego for analysis. Step 6: Compile data on editing effectiveness, GCT recipient production, performance benefits, and sterility creation. Analyze data. Synthesize and deliver findings and recommendations. Step 7: Continue to rear research lines and prepare for 2024 spawning season.