Breeding OA-resistant oysters

Crossbreeding and Selection for Resistance to Ocean Acidification in Pacific Oysters

Researchers used 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 investigated the potential of controlled crossbreeding to create genetic lines of Pacific oysters that were 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.


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.

The researchers identified the highest-performing oyster lines, and then continued to maintain stocks from the original cohort that were shown to be nominally resistant to OA. The researchers set the stage to work with industry partners for further validation of these promising results. The researchers planned to mate crosses of different hybrid lines to produce seed oysters for dissemination to commercial oyster operations that will test double hybrid lines for general performance compared to generic oyster seed in the years ahead. The evaluations assessed whether the progeny from the hybrids perform well on commercial farms that are subject to corrosive seawater conditions.