There are several expected outcomes of the project. The most important one is the determination of the tissues and pathways associated with enhanced biosynthesis and deposition of EPA and DHA in the muscle of fish fed feeds containing only sustainable plant-derived feed ingredients. Because the stocks being used in the selection program at the Hagerman Fish Culture Experiment Station are now being used in commercial production of a significant portion of the US trout industry (Idaho produces 72% of US farmed trout), markers obtained will have immediate impact on US rainbow trout production.

Furthermore, this information is applicable to other cultured finfish species and would assist in maintaining and potentially increasing US aquaculture production, especially salmon. Ability to grow fish efficiently on an all plant diet with acceptable EPA and DHA levels should lead to increased production of aquaculture feeds formulated with higher soy product incorporation.

Updated December 3, 2019:

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The research done in this project has provided new knowledge that overturns previous concepts regarding mechanisms that control or regulate bioconversion of linolenic acid, the only omega-3 fatty acid found in plant oils, to EPA and DHA, essential dietary nutrients for fish and healthful fatty acids for humans. Knowledge of these mechanisms will be used to identify genetic markers for use in selective breeding programs for salmon, trout and other farmed fish species to enhance fillet levels of EPA and DHA, and lead to higher use levels of soy oil in feeds for farmed fish to replace costly fish oil, and contribute to the production of sustainable aquaculture feeds.

The immediate impacts of the proposed research will be development of a strain of rainbow trout that exhibits enhanced deposition of EPA and DHA in muscle tissues (fillet) compared to commercial trout strains currently used by the US trout industry. Germplasm from the improved strain will be made available to commercial trout growers. This is currently being done with earlier strains of rainbow trout selected for improved growth when fed all plant-protein feeds. The impacts of the study will therefore be evaluated by successful transfer of germplasm to commercial producers and reported as such, furthermore the research station will continue selection for trait improvement. Other impacts will be identification of genetic markers that can be immediately used by companies producing trout eggs for growers in their selective breeding programs. Reporting will involve assessment of the extent to which these markers are used. Finally, use of new genetic markers in other fish species, starting with salmon, will be a longer-term impact. Evaluation and reporting will follow that used in the rainbow trout industry. Finally use of this improved germplasm will lead to formulation of commercial feeds utilizing substantially higher levels of protein and oils from plants.