Family-based breeding for production of higher-yielding Manila clam seed

Farming of marine bivalves provides high-quality protein and has a positive impact on the coastal environment. The U.S. is a top producer of the Manila clam (Japanese carpet shell, Ruditapes philippinarum) with reported sales of $31 M in 2019. Production of clams, however, has depended almost entirely on seed from wild stocks and natural recruitment, leaving the industry vulnerable to ocean change. In response to Topic Area 9.3 The Changing Ocean, this Phase I proposal seeks to develop a family-based breeding program for R. philippinarum and select for families with differential sex-ratios that may have contrasting yield potentials and environmental resilience. This proposal builds on prior research showing a relationship between sex-ratios and growth rates, and the possibility of identifying sex based on mitochondrial segregation patterns in embryonic clams. We propose to combine several technological innovations: (1) development of a repository of pair-mated, full-sibling families; (2) identification of primary sex-ratios at embryonic stages; (3) out-planting of families with differential sex-ratios for assessments of yield performances. Expected results could enable the development of future projects that will be focused on investigating the genetic bases for sex determination and biological underpinnings of differential growth and survival for the species.