Breeding OA-resistant oysters

Crossbreeding and Selection for Resistance to Ocean Acidification in Pacific Oysters

Researchers will use genetic approaches to develop broodstocks for the shellfish industry that are better adapted to increasingly corrosive seawater impacting our coasts and estuaries.

Principal Investigator

Jonathan Davis, Pacific Shellfish Institute and Taylor Shellfish Company, Inc.

Co-Principal Investigator

Brett Dumbauld, USDA Agricultural Research Service

Carolyn S. Friedman, University of Washington, School of Aquatic and Fishery Sciences

Steven Roberts, University of Washington, School of Aquatic and Fishery Sciences


Washington Sea Grant-supported research is investigating the potential of controlled crossbreeding to create genetic lines of Pacific oysters that are resistant to the effects of ocean acidification (OA) during early larval stages. Investigators crossbred oysters to create 42 intraspecific hybrid and 7 inbred lines. Embryos were subsequently raised at a hatchery and nursery, and then transferred for testing and maintenance to Thorndyke Bay, in Hood Canal. The researchers measured how resilience factors—such as growth rate and survivorship—of oysters from each of these lines changed when they were exposed to reduced pH during two larval phases: embryogenesis to the veliger stage and the transition from pediveliger to early spat.

Research Updates


Washington’s shellfish industry is challenged to produce enough Pacific oyster seed to satisfy growing demand. Human-caused environmental change intensifies these challenges: greenhouse gas emissions are causing ocean acidification (OA), which has already caused massive shellfish larvae die-offs. Developing oyster crops that are resilient to OA could help sustain aquaculture operations.

Results Thus Far

To better measure response to different ocean acidification (OA) conditions, investigators developed an enhanced, more reliable apparatus for assessing response of oyster embryos and late-stage larvae to low pH conditions. The improved apparatus allowed flow-through seawater control that enabled cultured microalgae to be added without changing water chemistry.

The researchers used a Bayesian statistical model on their hybrid oysters to identify the highest-performing lines. These lines are already in use in commercial shellfish production. During 2018, the researchers continued their analysis of the resilience of the oyster lines to OA. If the final results show some lines to be resilient to OA, researchers will make seeds from those lines available to interested growers, free of charge.