Project Grant 20226701637227

** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** AQUACULTURE IS BECOMING INCREASINGLY IMPORTANT TO RESOLVE THE CURRENT AND PROJECTED SHORTFALLS IN AQUATIC FOOD PRODUCTION. AMONG AQUACULTURE FISH SPECIES, SALMONIDS ARE THE MOST VALUABLE. THEY ARE CONSIDERED ONE OF THE MOST NUTRITIOUS AND HEALTHY FOODS BECAUSE OF THEIR HIGH OMEGA-3 FATTY ACIDS, PROTEIN, VITAMINS, AND MINERALS. AS SUCH, SALMONIDS ARE BELIEVED TO BE THE MOST CRITICAL DRIVERS FOR FINFISH AQUACULTURE AND HEALTHY FOOD CONSUMPTION. AMONG SALMONIDS, ATLANTIC SALMON IS THE MOST POPULAR AND CONSUMED FISH IN THE US.AT PRESENT, OVER 99% OF ATLANTIC SALMON AQUACULTURE PRODUCTION IS FROM OCEAN NET-PENS WORLDWIDE. HOWEVER, THE LIMITED US PRODUCTION OF ATLANTIC SALMON IN COASTAL PENS CONTINUES TO BE OVERSHADOWED BY FEDERAL AND STATE REGULATIONS AND LOSS OF SOCIAL ACCEPTANCE, PREVENTING ITS DOMESTIC GROWTH. THEREFORE, IT IS BECOMING INCREASINGLY EVIDENT THAT ALTERNATIVE FARMING SYSTEMS MUST BE USED FOR ATLANTIC SALMON AQUACULTURE TO EXPAND IN THE US. LAND-BASED RECIRCULATING AQUACULTURE SYSTEM (RAS) TECHNOLOGY IS A VIABLE AND SUSTAINABLE MEANS TO EXPAND US ATLANTIC SALMON PRODUCTION. IT PROVIDES THE ABILITY TO CAPTURE AND TREAT WASTE EFFECTIVELY, ENHANCES BIOSECURITY TO PREVENT FISH ESCAPES, MINIMIZES PATHOGEN ENTRY, OFFERS OPTIMAL CONDITIONS TO MAXIMIZE FISH PERFORMANCE, AND INCREASES FLEXIBILITY IN SITE SELECTION. RECENTLY, OVER $2.5 BILLION HAS BEEN ANNOUNCED TO INVEST IN RAS ATLANTIC SALMON PRODUCTION THROUGHOUT THE US. HOWEVER, FOR THE RAS ATLANTIC SALMON INDUSTRY TO BE THRIVING IN THE US, IT MUST BE CONTINUOUSLY OPTIMIZED AND OVERCOME BIOLOGICAL AND TECHNOLOGICAL HURDLES.EARLY SEXUAL MATURATION IS ONE OF THE SIGNIFICANT CHALLENGES IN FARMED ATLANTIC SALMON. IT WAS ESTIMATED AT 20-30% IN OPEN-WATER FARMING PRACTICES. SHOCKINGLY, PRECOCIOUS MALE MATURATION HAS BEEN REPORTED AS HIGH AS 80% BY HARVEST TIME IN LAND-BASED, CLOSED-CONTAINMENT GROW-OUT SYSTEMS. SEXUAL MATURATION IS ASSOCIATED WITH A SUBSTANTIAL DECREASE IN MUSCLE GROWTH DUE TO THE DIVERSION OF ENERGY INTO THE DEVELOPMENT OF THE GONADS. IT RESULTS IN DETERIORATION OF FLESH QUALITY AND AN INCREASE IN SUSCEPTIBILITY TO STRESS AND DISEASE. EARLY MATURATION IN RAS-GROWN SALMON CAN HAVE SIGNIFICANT BIOLOGICAL AND BUSINESS CONSEQUENCES. USING AN ALL-FEMALE POPULATION IS A PROMISING APPROACH FOR PREVENTING EARLY MATURATION IN RAS FARMING AS MOST GRILSING HAS BEEN ASSOCIATED WITH MALES. CURRENTLY, THE ONLY COMMERCIAL AVAILABLE ALL-FEMALE ATLANTIC SALMON SEED PRODUCTION RELIES ON USING A MALE STEROID (17 & ALPHA;-METHYLTESTOSTERONE ) TO REVERSE FEMALES (CARRYING XX SEX CHROMOSOMES) TO MALES THAT PRODUCE ALL-X SPERM. DUE TO REGULATORY HURDLES AND THE INCREASING CONCERN OF 17 & ALPHA;-METHYLTESTOSTERONE RELEASING INTO THE ENVIRONMENT, ALTERNATIVE APPROACHES TO PRODUCE AN ALL-FEMALE POPULATION ARE NEEDED. HENCE, WE PROPOSE AN ALTERNATIVE APPROACH THAT EMPLOYS FISH STERILIZATION AND GERM CELL TRANSPLANTATION TECHNOLOGY TO GENERATE THE ALL-X MILT FOR ALL-FEMALE SALMON PRODUCTION. BY TRANSPLANTING FEMALE GERM CELLS (CARRYING XX SEX CHROMOSOMES) TO STERILE MALE GONADS, ALL-X SPERM CAN BE PRODUCED IN THE RECIPIENTS AND USED FOR AN ALL-FEMALE PRODUCTION WITHOUT THE NEED OF USING STEROIDS.FOR A COMMERCIAL APPLICATION TO ACHIEVE COST-EFFECTIVE OPERATION, THE GERM-CELL-TRANSPLANTATION TECHNOLOGY NEEDS TO BE FURTHER OPTIMIZED TO ACHIEVE A HIGHER SUCCESS RATE. AS SUCH, WE WILL STUDY AND OPTIMIZE THIS TECHNOLOGY BY 1) SYSTEMATICALLY INVESTIGATING THE CANDIDATE FACTORS FOR IMPROVING FISH OVARIAN-GERM-CELL TRANSPLANTATION; 2) VERIFYING AND OPTIMIZING THE IMPROVED CONDITIONS IN TRANSPLANTATION; 3) PRODUCING ALL-MALE STERILE RAINBOW TROUT TO CARRY ATLANTIC SALMON OVARIAN GERM CELLS AND PRODUCE ALL-X SPERM SUCCESSFULLY. IT IS KNOWN THAT MALE ATLANTIC SALMON GENERALLY REACH SEXUAL MATURITY AT AGE 2 TO 3 YEARS, WHILE MALE RAINBOW TROUT MATURE AT AGE 1 TO 2 YEARS. THUS, THE GENERATION TIME FOR ATLANTIC SALMON ALL-X MILT PRODUCTION CAN BE SHORTENED THROUGH THE USE OF TROUT RECIPIENTS.IN SALMONIDS,SUBSTANTIAL INVESTIGATION OF THE FACTORS THAT INFLUENCE GERM CELL TRANSPLANTATION AND OPTIMIZING THE CONDITIONS THAT CAN ENHANCE TRANSPLANTATION EFFICIENCY IS VERY LIMITED DUE TO THEIR SEASONAL AVAILABILITY OF EMBRYOS AND A RELATIVELY LONG GENERATION TIME. THEREFORE, WE WILL USE FISH SPECIES THAT CAN SPAWN YEAR-ROUND AND HAVE A SHORT GENERATION TIME FOR THIS OBJECTIVE. ZEBRAFISH AND NILE TILAPIA ARE CONSIDERED GREAT MODELS FOR THIS PURPOSE SINCE THEY BREED YEAR-ROUND AND HAVE RELATIVELY SHORT GENERATION TIME, AND WELL-ESTABLISHED METHODOLOGIES WILL HELP THE OPTIMIZATION OF OVARIAN GERM CELL TRANSPLANTATION. THE OPTIMIZED CONDITIONS ACHIEVED IN ZEBRAFISH AND TILAPIA TRANSPLANTATION WORKS WILL BE EVALUATED AND MODIFIED IN RAINBOW TROUT AND ATLANTIC SALMON GERM CELL TRANSPLANTATION. WE WILL ESTABLISH AN OPTIMAL SALMONID GERM CELL TRANSPLANTATION SOP FOR ALL-FEMALE ATLANTIC SALMON PRODUCTION IN A COMMERCIAL SETTING.THE VALUABLE OUTCOMES OF THIS RESEARCH WILL HELP OVERCOME THE RESTRICTION OF USING 17 & ALPHA;-METHYLTESTOSTERONE TO REDUCE OR EVEN ELIMINATE THE USE OF SEX STEROIDS FOR ALL-FEMALE PRODUCTION, WHICH WILL SUPPORT AQUACULTURE DEVELOPMENT TOWARD MORE ENVIRONMENTALLY RESPONSIBLE AND SUSTAINABLE.