SILVERDALE -- Generations ago, Indigenous peoples pulled Olympia oysters out of the Puget Sound to cook and eat. Cooks built fires atop river and beach rocks until they were hot enough, then set oysters on top and covered them with seaweed and kelp to trap the steam. About 20 minutes later, they had fresh cooked oysters so flavorful they didn’t require seasoning.

Olympia oysters remained abundant in the Puget Sound until the 1800s, before they were overharvested, canned and preserved without any management of the species, Suquamish Tribe fisheries director Rob Purser said. The native oysters form clusters and harvesters would gather as much as they could, grabbing blocks of oysters rather than just taking a percentage and allowing oysters to reseed.

Today the Suquamish eat Pacific oysters that are mostly shipped over from Japan, said Purser. Though the imported oysters taste good and provide the same ecological benefits, the Olympia oysters have a traditional and spiritual value to the tribe.

The Puget Sound Restoration Fund (PSRF) is now working to restore habitat for the native oyster in Dyes inlet around Oyster Bay and Chico Bay, with a project this week to add to the 110 acres of Olympia oyster restoration completed throughout the Puget Sound.

“These Olympias are thriving under current conditions, which hasn't always been the case,” said Purser, who said the Tribe has partnered with PSRF along with state agencies and local governments in years past. “Now's the time to try to put as much habitat in place for them to attach to as possible.”

A barge full of oyster shells

On Tuesday, an almost 250-foot barge rolled into Dyes inlet from Tacoma, loaded with Pacific oyster shells. As the barge maneuvered over the tidelands, workers “sluiced” the empty shells from the deck with seawater. The team will spread 1,900 cubic yards of shells over up to 20 acres of tidelands, covering them in various densities.

Though the goal is habitat restoration for Olympia oysters, the PSRF is using Pacific oyster shells collected from shellfish industries in the state to conduct an aquaculture practice called “natural set capture,” which is usually done with cages or mesh sacks of shells. These Pacific oyster shells will serve as seasoned cultch for the Olympia oyster larvae to settle on and create a naturalized oyster bed over time.

“We're looking to regain space that is a natural oyster bed in this estuary,” said habitat restoration director Brian Allen. “In order to get there, we need to have populations developed to a certain point where they can both facilitate the development and then the persistence of the population.”

The PSRF has been working in Dyes Inlet for more than a decade restoring oyster habitat with similar shell amendments, surveying oyster populations, and studying and monitoring their development. Because of this work, the organization knew Dyes Inlet had a naturalized population of oysters that have a high magnitude for recruitment, a process where new oysters are incorporated into the population, Allen said.

The hope is that laying shells in the right position in the corner of Dyes Inlet will develop an oyster bed that will supply larvae for more recruitment within the system with ecological significance.

Healthy habitat contribution 

In addition to the cultural and spiritual value of the Olympia oyster to Indigenous peoples, establishing a naturalized oyster bed in Dyes Inlet could also have environmental benefits.

The oyster beds provide important environmental services in estuaries like filtering feeding, nitrogen cycling and food web enhancement, supporting a community of species, Allen said. Oyster beds create a structured habitat for tiny marine invertebrates that serve as prey for many important forage fish species that in turn feed Chinook and chum salmon that have high fidelity with the near shore as they enter Dyes Inlet.

Oyster beds also contribute to a diversity of estuary habitats like mud flats, eelgrass and gravel beaches, Allen said. “Having those kinds of diverse inlet habitats facilitates the natural function of and support for the native species that we care about.”

One hundred of oysters per square acre

It will take oyster larvae about a year to mature after they settle out of the marine plankton and glue themselves to a bit of shell supplied by the PSRF.

But the organization didn’t sluice the shells into Dyes Inlet in anticipation of the reproductive season. This attachment process happens between May and August, so the 20 acres of Pacific oyster shell will be ready when larvae are swimming around the estuary waters during late spring and summer of 2024.

“We are still working on the task of restoring Olympia oyster populations to the places where it was historically in the Salish Sea,” Allen said. “So for the oyster, it means taking back real estate where it used to occupy.”

The PSRF monitors the behavior of Olympia oyster settlements in Dyes Inlet and throughout the Puget Sound, Allen said. They intend to check in on recruitment about a year later around August 2024 during the low tide season to search for signs of natural recruitment. The real test will be to come back three and five years later to check on population development, he said.

“Success would mean a population development that is getting observed or measurable recruitment at least a few times within a decade,” Allen said. “We are looking for densities that get over 100 animals per square meter.”

Over the decades, the PSRF expects to see the budget of available Pacific oyster shell substrate to eventually shift towards Olympia oyster shell as the population develops, Allen said. Then,  the oysters will be forming three-dimensional structures that will act as a factory for epigenetic and vertebrate prey populations.

“We're really, really hopeful that the outcome in Silverdale is… gregarious settlement, relatively soon on the heels of the amendment and in 2028, '29, '30, where we're looking at a natural oyster bed that's tens of acres in space in Silverdale,” Allen said.

This article originally appeared on Kitsap Sun: Puget Sound Restoration Fund restoring Olympia oysters in Dyes Inlet