3,000 baby oysters transplanted in Morro Bay estuary as part of work to save native species

On Tuesday morning, two scientists joined with oyster farmers in the Morro Bay estuary to exchange jubilant high fives as they stood waist-deep in the bay’s chilly water.

Kevin Johnson, an aquaculture specialist with the California Sea Grant extension program at Cal Poly, and Shannon Baldwin, who’s working with Johnson as an oyster hatchery technician, had just set up five baskets each carrying 100 baby Olympia oysters at the Grassy Bar Oyster Co.’s farm floating near the center of the estuary.

The deployment of the baby oysters marked the end of a big step toward restoring the native oyster population to Morro Bay.

“I’m excited,” Baldwin said after jumping back onto a boat in the estuary. “We’ll get to see if all of our hard work up to this point pays off.”

The Pacific oysters sold by Grassy Bar and Morro Bay Oyster Co. are not native to the Morro Bay estuary, and instead originate from Asia. The Olympia oysters are the only native species to Morro Bay and the West Coast of North America.

The native species had previously been so abundant it was a large food source for indigenous peoples and European settlers. But years of habitat destruction, increased pollution and overharvesting led to their steep decline.

“We weren’t even sure if there were any Olympias left in the bay,” said Carolyn Geraghty, restoration program manager at the Morro Bay National Estuary Program.

But in July and August, national estuary program staff alongside Cal Poly students and faculty found a total of 482 Olympia oysters in Morro Bay. Geraghty noted that this was a big cause for excitement, as it showed there was at least a small surviving population there.

3,000 Olympia oysters deployed in Morro Bay estuary

Tuesday’s deployment of the Olympia oysters was the culmination of about two years of work by Johnson, aided by Baldwin, and funded by The Nature Conservancy.

In March, Baldwin had harvested several adult Olympia oysters found near Tidelands Park and brought them to the Cal Poly Pier in Avila Beach to begin carefully growing them in tanks. There are now about 15,000 baby oysters in the tanks, Johnson said.

On Tuesday, Baldwin and Johnson took 3,000 of those baby oysters — none any larger than a dime — put them in buckets with some ocean water and transported them to Morro Bay.

Then, they divided 500 of them among five special plastic baskets and hung them at the Grassy Bar Oyster farm, while transplanting another 2,500 in a floating nursery at Morro Bay Oyster Co.’s farm near the Morro Bay T Pier.

Next, Johnson, Baldwin and Cal Poly students will regularly monitor the oysters to see if they survive and grow.

“We really don’t know how fast they’ll grow here,” Johnson said, adding that he’s pretty confident the Olympia oysters will survive.

The restoration process is an experiment, Johnson noted, so if the Olympia oysters end up not surviving, that just means the researchers will need to try different methods.

By placing thousands of Olympia oysters in the estuary, Johnson is hopeful that the native species could repopulate enough to not only serve the commercial farms, but also become naturally abundant again along the rocky shores of Morro Bay.

Restoration of oysters would benefit Morro Bay ecosystem

Restoring the native oysters in the estuary would have multiple benefits.

For one, the animals are filter feeders, meaning they draw in sea water and gain nutrients from the various organisms floating around. This method of eating leads to clearer water, which can then help a whole suite of other animals and plants better survive in the estuary.

And the oyster farmers are hopeful the Olympia oysters grow to market size.

“How cool would it be to one day have native, restored Olympias in restaurants?” remarked Neal Maloney, owner of the Morro Bay Oyster Co. “We’d be giving people a real taste of our bay.”

George Trevelyan, owner of Grassy Bar Oyster Co., noted that it’ll likely take the Olympia oysters about two years to reach market size, and they couldn’t sell them until they receive the proper permits from the state.

“I’m really interested in this restoration,” Trevelyan said. “They’ll have a unique taste and provide a really special local delicacy that’s different from the Pacific oysters.”

Also, adding to the potential benefits is the fact that raising two types of oysters on their farms will transition the companies away from having a monoculture. Should a disease come along and impact one species, it’s likely the other species would be more resistant and able to survive, Trevelyan said.

That’s likely especially true for the native Olympia oysters.

“We’re hoping that they’re naturally more adapted to grow and deal with the conditions here,” Johnson said.

The work by Johnson and Baldwin is being mirrored at the Elkhorn Slough in the Monterey Bay and Tomales Bay north of Point Reyes.

There, researchers are also deploying the native Olympia oysters in hopes of restoring the populations.

“The impacts of all of this are ideally net positive,” Johnson said. “This is really exciting stuff and I’m looking forward to seeing how the oysters do.”

Mackenzie Shuman

The Tribune

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Mackenzie Shuman primarily writes about SLO County education and the environment for The Tribune. She’s originally from Monument, Colorado, and graduated from Arizona State University’s Walter Cronkite School of Journalism and Mass Communication in May 2020. When not writing, Mackenzie spends time outside hiking and rock climbing.