An oyster farm in Washington. (Photo by Kent Wang.)

The first suspects were bacteria.

Something was killing the microscopic oyster larvae at the hatcheries in Washington’s Dabob Bay and in Oregon’s Netarts Bay in recent years. The tiny oyster shells were crumbling faster than they could grow back, says Bill Dewey, public policy director for Taylor Shellfish Farms, which harvests geoducks, oysters, and other shellfish around Puget Sound. And soon, hatchery experts realized increasing ocean acidification was the true culprit. But what exactly that means, is yet to be determined.