Indigenous sea gardens 

For those who know how to read them, the signs have long been there. Like the towering mound of 20 million oyster shells all but obscured by the lush greenery of central Florida’s Gulf Coast. Or the arcing lines of wave-weathered stone walls strung along British Columbia’s shores like a necklace. Such features, hidden in the landscape, tell a rich and varied story of Indigenous stewardship. They reveal how humans carefully transformed the world’s coasts into gardens of the sea—gardens that produced vibrant, varied communities of marine life that sustained Indigenous peoples for millennia. And in certain places, like on the west coast of North America in what is now Washington State and where the Swinomish are building a new sea garden, these ancient practices are poised to sustain them once again.

“I see it as a way for our people to be reconnected to our place, to be reconnected to each other, and to have a purpose, to have a responsibility that goes beyond us,” says Alana Quintasket (siwəlcə?) of the Swinomish Tribal Senate.

Across the planet, Indigenous communities, from the Heiltsuk in British Columbia, to the Powhatan on the Chesapeake Bay on the United States’ Atlantic Coast, to the Māori in New Zealand, have successfully stewarded the sea for thousands of years. These communities avoided diminishing their productive sea gardens despite, in some cases, seeing harvests that rival modern commercial fisheries.

The scale of historical Indigenous oyster gardening, for instance, cannot be overstated. On America’s southeastern Atlantic coast, in the modern states of South Carolina, Georgia, and Florida, Indigenous peoples whose descendants include the Muscogee built gargantuan monuments out of oyster shells. These structures could reach 30 meters high or more.

“These people are taking billions of oysters—literally billions of oysters—to form a single site,” says Torben Rick, an archaeologist at the Smithsonian’s National Museum of Natural History. The monuments were deeply significant, serving as sites for human burial, feasting, and other ceremonies and rituals.

Scientists studying historical overfishing published a study showing how, starting around the 19th century, oyster stocks suffered a “moving wave of exploitation” that traveled down the Atlantic and Pacific coasts of North America and the eastern coast of Australia. The capitalist commercial fisheries that arrived with European colonization and settlement, Rick says, undid thousands of years of sustainable prosperity. “Within 50 years, 100 years, maybe even less in some areas, they’ve depleted that stock.”

But to Rick, that modern narrative of rampant decline is only part of the story. By focusing on the past few centuries, that paper—and many other important scientific studies and conversations—overlooks the ways in which major Indigenous oyster fisheries managed to sustain mass productivity for millennia. Paying these fisheries more attention, says Rick, could have far-reaching implications for restoring and managing the flagging oyster populations left today. To fill in the rest of the story, Rick assembled a diverse, multidisciplinary team of researchers to revisit the history of oyster fishing in the same places as in the 2004 study, but they started their clock in the 1800s and looked backward.

Relying on archaeological and ethnohistorical records, the team followed how changes in the natural world—such as the thawing of glaciers more than 11,000 years ago and the stabilization of sea levels thousands of years later—created an abundance of estuaries and an explosion of intensive oyster harvesting by Indigenous communities for 5,000 to 10,000 years. Through this and other insights, the team is redrawing the historical ecological baseline for these oyster stocks.

Smithsonian