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Ancient Indigenous ‘clam gardens’ could be modern-day climate solution

June 8, 2023
(Camille Vernet)

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For close to four millennia, “clam gardens” on beaches on the west coast of B.C. have provided First Nations with a supply of not just clams but other types of seafood.

In the aftermath of the brutal 2021 heat dome on the West Coast, there’s renewed interest in this ancient aquaculture technique.  Five days of stifling heat killed hundreds of people and billions of sea creatures. But scientific experimentation by researchers from Simon Fraser University, in collaboration with Coastal Salish First Nations, indicates clam gardens help sea life stay cooler.

The research aims to show how ancient Indigenous practices offer a modern-day solution to coping with climate change.  SFU master’s student Emily Spencer wanted to know whether the clam gardens, with their steady supply of cool water, could help keep shellfish cooler and protect them from future episodes of extreme heat.  

Ken Thomas was more than willing to demonstrate the age-old practices of maintaining clam gardens on a recent visit to Russell Island, which lies close to the better-known Saltspring Island, off the southeast coast of Vancouver Island.  He’s intimately involved with the research being carried out here. A tall, broad-shouldered man in his 50s, Thomas is in charge of fisheries, wildlife and natural resources for the Penelakut First Nation.

He picked up a three-pronged rake and began “tilling” the sand. As he pulled the rake down, he explained that it helps keep the beach from becoming “hard and dormant.” It also revealed small clams and crabs living close to the sand’s surface. 

When the idea of reconstructing a clam garden on this beach was broached a few years ago, Thomas wasn’t convinced. Elders directed him and others to pick up large rocks from higher up the shore and arrange them to form a rough seawall close to the low tide line. “At first it was, ‘OK, yeah, I’ll go move rocks, whatever,'” Thomas told What On Earth. But something shifted in him as he heard the elders tell stories from the past. He began to understand and appreciate how a technique so old could work so well for him and his children. 

“It really touched me in a way that I can’t explain,” Thomas said. “Every time I moved a rock and placed it on the wall, I was like, wow, my ancestors touched these rocks, and here I am putting it back, restoring it back to what it was meant for.”

The rock wall is about a metre and a half tall and runs the length of the beach, about 750 metres. It ensures that ocean water recedes slowly as the tide goes out, maintaining a cool, wet environment until the tide comes back in. That makes the beach a kind of shelter or refuge — or pantry, according to Thomas’s forebears.

“To this day, you still hear our elders saying, ‘When the tide’s out, the table’s set. Go get your food.'”

Working with Thomas to ensure Indigenous knowledge and practices are respected, Spencer designed an experiment that used Ikea chairs, propane torches and non-flammable material to recreate the conditions of the heat dome on the beach. “We created little saunas for the clams,” she said. 

At low tide, they erected a series of these small tents with the clams inside. They did this for five days straight — replicating the length of the heat dome. After that, the clams were scooped up and taken to labs for analysis.

Spencer’s results — to be submitted for peer review in the coming months — found the gardens kept the clams cooler even with the added heat. This effect suggests the gardens are more than a way to create and maintain a food source. They could also be a climate adaptation strategy for an entire ecosystem.

Spencer’s supervisor at SFU, marine ecologist Anne Salomon, is excited about the prospect. “We’re desperately looking around the world for climate solutions, and here’s one that is at least 4,000 years old,” Salomon said. “It works. It’s a very simple process, and so I am very optimistic about the future when I see examples like this.”

For Ken Thomas, it’s confirmation that his people knew how to use the resources responsibly for millennia. That’s one reason he so readily agreed to go ahead with Spencer’s experiment.   “Just last night, we had a nice pot of steamers, manila clams and little neck clams [to eat]. So you know, we still utilize it and we still love it and we want it around forever.”

– Laura Lynch