In Triangle Cove, a small embayment tucked into Camano Island off Port Susan Bay, the Stillaguamish Tribe of Indians is working to establish an oyster population that could someday support tribal harvests and reconnect the tribal community with a food source eaten by their ancestors.
“Shellfish have always been a big part of who Stillaguamish are,” said Kadi Bizyayeva, Stillaguamish vice chair and the tribe’s fisheries director.
With an eye toward enhancing the tribal community’s access to shellfish, the tribe in 2021 purchased tidelands here. After years of habitat restoration and some small-scale testing of oyster outplantings, the tribe this spring acquired a large quantity of Olympia oysters from the Puget Sound Restoration Fund; an estimated 322,500 Olympia oyster larvae grown on Pacific oyster shells, called spat, and another 40,000 juvenile Olympia oysters called singles.
The Olympia oyster is the only oyster species native to the Puget Sound region. It was consumed by Coast Salish communities for generations before overharvest, habitat destruction and pollution led to a major decline.
In Triangle Cove, intertidal shellfish habitat was lost to the diking and draining of the Stillaguamish River delta, decades of logging and wood mill operations and the introduction of the invasive marsh grass Spartina, said Franchesca Perez, marine biologist for the Stillaguamish Tribe. Much of that activity contributed to sediment buildup, which smothered the sandy gravel substrate where shellfish would naturally flourish.
Thanks to recent habitat restoration efforts including the eradication of the invasive grass, the sediment buildup has been eroding away, revealing the layer of gravel and sand that could again support shellfish growth.
Now, the tribe is testing whether the Olympia oysters placed in Triangle Cove this year can establish a self-sustaining population.
“Many parameters for success exist,” Perez said.
Those include the cove’s partial protection from wave action, retention of some water during low tide and persisting shellfish populations like mussels and manila clams—all clues that the Olympia oyster might do well here.
The tribe is testing Olympia oyster spat secured in 150 mesh bags. The majority was distributed into the cove’s tidepools, with some left in an active channel for comparison. The oyster singles were placed in plastic crates suspended off the muddy bottom of the tidepools to test for protection against predators and sediment.
In some areas, water quality monitoring devices were submerged, tracking the temperature, oxygen and salinity levels, and chlorophyl content around the oysters.
Perez and other staff of the Stillaguamish Natural Resources Department visit regularly to obtain data from the devices, tally oyster survival rates at a subset of locations and measure a sample of the oysters for growth rates.
It takes several years for Olympia oysters to reach a harvestable size, but monitoring over the summer has already shown promising growth in the study area, Perez said. Some of the oysters have grown from smaller than 0.25 inches long to about 1.5 inches from May through August.
If successful, reintroducing Olympia oysters to the area will benefit the intertidal ecosystem and support tribal harvest of a cultural resource that was once nearly lost.
“Restoring them isn’t just about being a good steward of the environment; it’s about taking care of our culture and making sure future generations will be able to take part in our traditions,” Bizyayeva said.
Franchesca Perez, marine biologist for the Stillaguamish Tribe, left, and Derek Arterburn, natural resources technician, sort a sample of Olympia oysters growing on Pacific oyster shells in Triangle Cove. Photos and story by Kimberly Cauvel.
