It shouldn’t have surprised me to learn that there is evidence of clam gardening from Washington through British Columbia and up to Alaska. The Coast Salish tribes are globally known for existing on a bounty of salmon, but the middens of herring bones and bivalve shells found along the coast here are strong evidence that these were a significant part of the diet as well.
Similar to rice terraces, where the steep slopes of a hill are graded and supported with rock walls, the clam garden is a form of aquaculture called mariculture- or “sea farming”. As demand for seafood continues to rise globally, the World Bank, U.N. Food and Agriculture Organization, and many others are looking for ways to farm more seafoods more efficiently. I know many people who reject aquaculture as a solution to food production because they’d rather focus on reducing over harvesting, but I suspect that mostly they are thinking about how unsustainable farming carnivorous fish, like salmon, has been. This idealism I hear so often among ocean conservationists doesn’t take into account that no matter your personal opinion, aquaculture is the only growing food sector globally for a few years now. Further, the environmental footprint and energy costs of seafoods varies widely, where shellfish seems to have the lowest environmental cost and can even improve water quality. [After reading The Evolving Sphere of Food Security out of Stanford I am more familiar with these nuances of energy needs for food production and believe that we must look carefully at how aquaculture practices vary]
Scientists from Simon Fraser University and University of Washington looked at modern clam gardens and planted multiple species to compare the growth of wild clams versus farmed clams. By digging and changing the shape and water circulation of the intertidal zone, you can essentially create more prime habitat for shellfish. This resulted in four times as many butter clams and twice as many littleneck clams, as well as faster growth rates. This is really incredible results for what is essentially organic, low impact farming of healthy proteins!
Now, if only we could convince Seattle Tilth to add some clam gardening projects into the home gardening movement that has gotten such a foothold in the community, I’d be- you guessed it- happy as a clam.