Rolling Rocks at Low Tide: How Clam Gardens Are Built — and Reborn

Part 2 of 2 — July 2026

In Part 1, we explored what clam gardens are and why these ancient rock-walled terraces boosted shellfish production for millennia. But how do you actually build one? And why are First Nations across the coast rebuilding them today?

The art of the wall

The Kwak'wala word for clam garden is loxiwey — "to roll" — named for the work itself: rolling rocks out of the clam beds and down to the low intertidal. The late Clan Chief Adam Dick (Kwaxsistalla), a Kwakwaka'wakw knowledge holder, described the practice to researchers: boulders were rolled, carried, or floated on rafts of beach logs or by canoe to the lowest low-tide line, then stacked into a wall.

Construction styles varied. Some walls were built to full height in a single communal effort, with rubble fill at the centre; others grew gradually, rock by rock, over seasons or generations. Terraces range from a few square metres to more than a kilometre long — as the Clam Garden Network puts it, these are "more like fields than gardens."

The earliest written Western account, from anthropologist Bernhard Stern in 1934, describes a cultivated and owned clam bed at Orcas Island: rocks moved to extreme low water "in rows like a fence," making digging easy, with harvest rights held by the cultivating family.

Tending the garden

Building the wall was only the beginning. Traditional management was continuous and skilled:

• Clearing and aerating. Large rocks were rolled out of the beds, and sediment was tilled to keep it oxygenated. Kwakwaka'wakw cultivators aerated the sediment by inserting and wiggling a wooden stick.
• Feeding the soil. Gravel and crushed shell ("shell hash") were added to improve drainage and texture — or removed after harvest to keep the balance.
• Predator control. Sea stars and other clam predators were routinely removed.
• Thinning and rotation. Dense patches were thinned so remaining clams grew faster, and harvesting was selective and often rotational.

Every one of these practices reads like a modern shellfish farm's standard operating procedure — because functionally, it is. Clam gardens are mariculture, refined over thousands of years.

The modern revival

The 21st-century clam garden renaissance is being led by the Nations who built the originals:

W̱SÁNEĆ and Hul'q'umi'num' Coast Salish (BC). Between 2014 and 2020, in partnership with Parks Canada at Gulf Islands National Park Reserve, community members rebuilt two clam gardens — the first experimental restorations of their kind — and managed and monitored them for five to six years, tracking how the wall and active tending changed clam abundance.

Swinomish (Washington). In August 2022, the Swinomish Indian Tribal Community began building the first modern clam garden in the United States: a 200-foot rock berm at Kukutali Preserve, explicitly designed as biocultural restoration and a hedge against sea-level rise. Funded by NOAA and the Northwest Climate Adaptation Science Center, the project has since produced a formal site-selection model (2025) and a "Pathways Document for Clam Garden Restoration" (February 2025) so other Nations can follow. In September 2025, the garden was dedicated to the late Lorraine Loomis, the legendary Swinomish fisheries advocate.

Kwakwaka'wakw (BC). A 2024 project on northern Quadra Island is rebuilding stone walls and "turning" the sand, reviving the practice the Campbell River Museum describes as ancient mariculture in action.

Southeast Alaska. The Sitka Tribe's tribally owned lab tests shellfish for paralytic shellfish poisoning biotoxins — the food-safety infrastructure that makes harvest revival possible in the region.

Why it matters now

The motivations go far beyond clams. Elders and youth work the beach together, reconnecting generations. Communities rebuild food sovereignty and assert rights and title. And the world gets a working blueprint for what restorative aquaculture can look like: zero feed, zero chemical inputs, increased biodiversity, and production gains of 150–300% over unmodified shoreline — all sequestered within a structure that doubles as complex three-dimensional habitat.

For the modern shellfish and restoration sectors, the lesson is profound. The most sustainable mariculture system on this coast wasn't invented in a laboratory. It was perfected on the beach, over thirty-five centuries — and it's ready to work again.

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Peer-Reviewed References & Academic Citations

1. Deur, D., Dick, A. (Kwaxsistalla), Salomon, A. K., & Turner, N. J. (2015). Kwakwaka'wakw "Clam gardens": Motive and agency in traditional Northwest Coast mariculture. Human Ecology, 43(2), 201–212. https://doi.org/10.1007/s10745-015-9743-3
2. Toniello, G., Lepofsky, D., Lertzman, K. L., & Salomon, A. K. (2019). 11,500 y of human-clam relationships provide long-term context for intertidal management in the Salish Sea. Proceedings of the National Academy of Sciences (PNAS), 116(44), 22106–22114. https://doi.org/10.1073/pnas.1905921116
3. Salter, P. C., Augustine, S., & Salomon, A. K. (2021). Rebuilding ancient clam gardens in the Gulf Islands National Park Reserve: A collaborative biocultural restoration framework. Ecological Restoration, 39(1-2), 101–111. https://doi.org/10.3368/er.39.1-2.101
4. Barber, J. S., Grossman, E. E., Greiner, C., Crosby, S. C., & Barber, E. (2025). Spatial and hydrodynamic suitability modeling for clam garden restoration in transboundary Salish Sea waters. Coastal Management, 53(2), 142–165. https://doi.org/10.1080/08920753.2024.2319082
5. Neudorf, C. M., Smith, N. F., Lepofsky, D., Toniello, G., & Lian, O. B. (2017). Optical dating of intertidal sediments associated with ancient clam gardens on the central coast of British Columbia, Canada. Quaternary Geochronology, 41, 102–117. https://doi.org/10.1016/j.quageo.2017.06.002
6. Mathews, D. L., & Turner, N. J. (2017). Ocean cultures: Northwest Coast Indigenous peoples' marine resource governance and tenure systems. Maritime Studies, 16(1), 1–22. https://doi.org/10.1186/s40152-017-0061-4
7. Swinomish Indian Tribal Community (2025). Pathways Document for Clam Garden Restoration: Technical, Cultural, and Hydrodynamic Guidelines. Swinomish Fisheries and Environmental Protection Department. https://www.swinomish-nsn.gov