Dennis Hedgecock combines expertise in genetics with an understanding of the larger issues of marine organisms and ecosystems. His research focuses on the population, quantitative, evolutionary and conservation genetics of marine fish and shellfish, including Pacific oysters, white seabass and Pacific salmon. A leading scientist in the field of oyster aquaculture and genetics, Hedgecock uses genetic mapping and functional genomics to study the genetic basis of hybrid vigor in Pacific oysters, a commercially important species in modern aquaculture. Hedgecock develops and improves crossbreeding techniques for farmed Pacific oysters, and has produced high-yield hybrid oyster varieties. Ultimately, his work may shed light on the basis for hybrid vigor in corn and other crops and on the maintenance of genetic diversity in natural populations. In his work with Pacific Chinook salmon of the Sacramento River and Central Valley, he developed novel genetic markers and tools that enabled scientists to distinguish between the rare endangered "winter-run” salmon and closely related salmon runs, work that proved essential in building an effective captive breeding program and evaluating its impact. Hedgecock investigates how enhancing fish populations through large hatchery programs impacts the genetic diversity of wild populations, and is currently examining the issue in local white seabass. Other research interests include the design of marine reserves, the impact of non-native species on ecosystems and fishery management issues.