Jan. 29 (UPI) -- After more than a century of overharvesting and industrial pollution, the Pacific Northwest's only native oyster is making a comeback in Washington's Puget Sound.
The tiny, but resilient, Olympia oyster, or "Oly," is becoming a delicacy again at seafood restaurants after almost being wiped out from 95 percent of its habitat along 2,500 miles of estuary shoreline.
"Olympias are different. They're feistier," said Shina Wysocki, owner of Olympia's Chelsea Farms, which specializes in shellfish. "They survived through all that pollution. Maybe the ones that are left are so strong, and we just got the toughest brood stock."
A 25-year restoration plan is attempting to bring back some of the dense, foot-deep oyster beds that once thrived over about 10,000 acres along the inlet bays of Puget Sound. Oyster bed ecosystems filter algae from seawater and provide habitat for numerous sea creatures.
"This is not a species that is going extinct. It is present throughout this historic range, but in very small numbers," said Betsy Peabody, executive director of the non-profit Puget Sound Restoration Fund. "Olympias are one of the foundational species native to this area. We've lost the lower intertidal habitat structure and the marine architecture that helped support other organisms and critters."
The Puget Sound Restoration Fund set a goal by 2020 to restore 100 acres of dense oyster bed habitat, and it has restored 84 acres so far.
Olympia oysters were rare during years when logging and industrial runoff polluted the bay, said former oyster farmer Marlin Holden, an elder of the Jamestown S'Klallam Tribe and now in his 70s.
"They were almost extinct there for a while. They were once the food of our ancestors," Holden said.
The tribe now operates an oyster farm on tribal land repurchased from logging companies and cleaned up. Workers have begun to breed Olympias.
"They were once the mainstay oyster of our people," Holden said. "I hope we can eat them soon at our tribal picnics."
Olys are smaller and pack a stronger, more robust flavor than Pacific oysters typically served at raw bars.
"They tend to taste of horseradish and copper, a very strong flavor, similar to a European flat oyster," said oyster farmer Wysocki.
During the Gold Rush, starting in 1850, early Puget Sound settler shellfish farmers dredged out entire beds of oysters. The shellfish were shipped by schooner to San Francisco, where they were served with bacon and eggs in a dish called the Hangtown fry. Mark Twain slurped Olympias on the half-shell at the Occidental Hotel in 1864.
Industrial pollution hurt
Then came industrial pollution. Starting in the 1920s, paper pulp mills and logging operations poured effluence into Puget Sound. Native oysters, buried in goopy silt, could not survive. Toxic pulp liquor interfered with larvae breeding.
In the 1990s, the number of native Olympias had dropped so low that Washington's Department of Fish and Wildlife declared the species a candidate for listing as "endangered, threatened or sensitive."
But given the right environment, Olympias are hardy opportunists and will thrive, said marine biologist Paul Dinnel of the Skagit County Marine Resources Committee.
Since 2002, Dinnel and volunteers have spread seeded oyster shells along the tidewaters of Fidalgo Bay near Anacortes, Wash., where the number of native oysters had dropped to almost zero.
"From the the original seed of 50,000 larvae, we now have almost 3 million oysters throughout the bay," Dinnel said.
Better survival rates
Olympias also appear to be better able than other oysters to withstand increased acidification of seawater.
Ten years ago, a die-off of commercial Pacific oyster larvae in Puget Sound was traced to lower pH in the ocean water. Carbon in the water was binding in a chemical reaction with calcium, leaving less calcium for the larval baby Pacific oysters to make their shells.
"A decrease in pH makes it harder for Pacific oysters to make their shell, it takes more energy to make the shell very quickly and they often don't make it," said George Waldbusser, associate professor in ocean ecology and biogeochemistry at Oregon State University, who helped identify the problem.
Olympia oysters grow slower in the larval stage, and don't need as much calcium all at once, Waldbusser found. Olympia larvae also brood protected inside their mother's shell instead of being broadcast into the water at the seed stage like Pacific oysters.
Today, commercial shellfish farmers monitor the pH level in hatchery water to protect baby Pacific oysters during their first days.
But even after the larval stage, Olympias are more robust than other types of oysters, Wysocki said.
High survival rate
Almost 90 percent of the Olys survive to harvest, she said, while half of the operation's Pacific oysters die.
The return of native oysters to Puget Sound is a reminder of the importance of the entire ecosystem to all shellfish farmers, who are part of a $270 million industry, Wysocki said.
"The Olympia oyster tells the story of how we were making mistakes in how we were managing Puget Sound early in our history as settlers," she said.
"Olympias dying off was one of the first signs that oyster farmers had to change. And their story resonates with people. Plus, they're delicious, and that doesn't hurt, either."