Hybrid Vigor in Pacific Oysters: An Experimental Approach Using Crosses Among Inbred Lines.

Hedgecock, D., D. J. McGoldrick, and B. L. Bayne. 1995. Hybrid vigor in Pacific oysters: An experimental approach using crosses among inbred lines. Aquaculture 137:285-298.

This study was the first experimental demonstration that crosses of inbred parent lines produced hybrid vigor for yield in the Pacific oyster. Yield or the amount of biomass produced per unit area or volume is a composite trait, reflecting both survival and growth. This paper follows Griffing (1990) in defining hybrid vigor as performance of hybrid offspring exceeding that of the better parent.

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Bivalve Genomics: Complications, Challenges, and Future Perspectives.

Curole, J. P., and D. Hedgecock. 2007. Chapter 29. Bivalve genomics: Complications, challenges, and future perspectives. In: Aquaculture Genome Technologies, Liu, Z. (editor), Blackwell Publishing, Ames, Iowa, pp. 525-543.

This book chapter reports progress in bivalve genomics, mainly with the Pacific oyster, in relation to genetic improvement.

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Bayesian Hierarchical Modeling of Yield in Incomplete Diallel Crosses of the Pacific Oyster Crassostrea Gigas.

Yin, X., and D. Hedgecock. 2019. Bayesian hierarchical modeling of yield in incomplete diallel crosses of the Pacific oyster Crassostrea gigas. Aquaculture 510:43-50.

The Pacific oyster shows dramatic hybrid vigor for yield and potential for rapid improvement through crossbreeding. Hybrid vigor is assessed by crossing inbred parent lines, acting as male and female parents, in all possible combinations; such a cross is called a “diallel.” Traditional statistical methods for analyzing diallel crosses are sensitive to missing information, which is common in practice. In this paper, part of the Ph.D. dissertation of Xiaoshen Yin, we use computer simulations to test the ability of a Bayesian hierarchical model to predict offspring and to rank parent lines. This model accurately predicts yield of offspring present in incomplete diallels and helps identify superior parent lines.

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Heterosis for Yield and Crossbreeding of the Pacific Oyster Crassostrea Gigas

Hedgecock, D., and J. P. Davis. 2007. Heterosis for yield and crossbreeding of the Pacific oyster Crassostrea gigas. Aquaculture 272S1: S17–S29.

This paper provides major evidence for hybrid vigor in the Pacific oyster and lays the foundation for Pacific Hybreed’s crossbreeding program. Hybrid vigor is the dramatically greater yield, resilience, and uniformity in the offspring of a cross between two inbred parent lines.

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Nonnative Oysters in the Chesapeake Bay

Committee on Nonnative Oysters in the Chesapeake Bay [J. Anderson and D. Hedgecock (Co-Chairs), M. Berrigan, K. Criddle, W. Dewey, S. Ford, P. Goulletquer, R. Hildreth, M. Paolisso, N. Targett, R. Whitlatch]. 2004. Nonnative Oysters in the Chesapeake Bay. National Research Council of the National Academies. The National Academies Press, Washington, D.C. 325 pp.

Shellfish have been transported and introduced by humans to areas outside of their native ranges for centuries. This study by the National Research Council, which was co-chaired by Pacific Hybreed founder Hedgecock, examined the general biological, legal, and economic consequences of introducing non-native species of shellfish, focusing, in particular, on a proposal to introduce the non-native Suminoe oyster into Chesapeake Bay to replace stocks of the native eastern oyster, which had been devastated by over-fishing and diseases.

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Genetics of Shellfish on a Human-Dominated Planet

Hedgecock, D. 2011. Genetics of Shellfish on a Human-Dominated Planet. Chapter 12, in: Shellfish Aquaculture and the Environment. Shumway, S. E. (editor). Wiley-Blackwell, pp. 339-357.

This book provides resource managers and policymakers with background on issues pertaining to shellfish aquaculture. Chapter 2, co-authored by Pacific Hybreed founder Davis, provides a perspective on the role that the shellfish industry has in maintaining the environmental integrity of coastal environments suitable for shellfish aquaculture and associated commercial shellfisheries and in shaping public policy with regard to sustained multiple use of near-shore marine environments. Chapter 2, by Pacific Hybreed founder Hedgecock, discusses three broad areas of genetic impact, translocations or introductions of shellfish, interbreeding between farmed and wild stocks, and domestication and genetic improvement of shellfish in aquaculture.

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Aquaculture: the Next Wave of Domestication.

Hedgecock, D. 2012. Aquaculture: the Next Wave of Domestication. In: Biodiversity in Agriculture: Domestication, Evolution, and Sustainability. Gepts, P. L., T. R. Famula, R. L. Bettinger, S. B. Brush, A.

Aquaculture, the fastest growing sector of global food production, accounts for nearly 40% of aquatic production and will soon surpass capture fisheries, forecast to collapse by mid-century.

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Boom-and-Bust Production Cycles in Animal Seafood Aquaculture.

You, W., and D. Hedgecock. 2018. Boom-and-bust production cycles in animal seafood aquaculture. Reviews in Aquaculture, available online. https://onlinelibrary.wiley.com/doi/full/10.1111/raq.12278.

In this paper, using data from the United Nations Food & Agriculture Organization, we document widespread boom-and-bust production cycles in marine aquaculture. Boom-and-bust production cycles have historically occurred in small aquaculture stocks, but the pattern appears to be spreading to larger and larger stocks and is having an increasing and unsustainable impact on global aquaculture production and aquatic biodiversity. We need to know more about diseases and on how to breed robust, disease- and stress-resistant aquaculture stocks.Boom-and-bust production cycles in animal seafood aquaculture.

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