Production of all-female, triploid Manila clam seed for U.S. West Coast growers

On the U.S. West Coast farming of Manila clam second largest crop behind Pacific oystersrelies on hatchery propagation of seed from wild stocks. Post-harvest spawning of clams insummer results in complete product loss as growers cannot sell or replant spawned clams. Thereare no breeding programs for the Manila clam and sterile triploid stocks are not commerciallyavailable as for the Pacific oyster despite being an obvious solution to post-harvest spawning.Aligned with Topic Area 8.7 this proposal seeks to (1) eliminate post-harvest spawning ofManila clams annual losses of more than $0.25 M in product and reputational damages and (2)increase yields by 20% in a single generation using faster-growing all-female seed whichwould add about $5 M annually.The project will bundle three technical advances required to realize the value propositions: (1)implementation of strip-spawning; (2) induction of triploidy and tetraploidy; and (3)identification of primary sex-ratios in full-sib clam families at the 2- or 4-cell embryo stagefollowed by rearing of families with contrasting sex-ratios. Phase I will set the stage fordevelopment in Phase II of genetic markers to confirm pedigrees and enable mapping of sex- determining genes. Strip-spawning Manila clams will provide access to unfertilized eggs allowcontrolled crosses and permit direct-induction of triploidy in female-biased families andtetraploidy in male-biased families allowing for commercial triploid production by a simple4N♂ — 2N♀ cross.The project will transform Manila clam aquaculture from exploiting captivewild stocks to farming of sterile high yielding all-female strains.