Clam Gardens

While there is increasing recognition among archaeologists of the extent to which non-agricultural societies have managed their terrestrial ecosystems, the traditional management of marine ecosystems has been largely ignored.  In this paper, we bring together Indigenous ecological knowledge, coastal geomorphological observations, and archaeological data to document how Northwest Coast First Nations cultivated clams to maintain and increase productivity.  We focus on “clam gardens”, walled intertidal terraces constructed to increase bivalve habitat and productivity.  Our survey and excavations of clam gardens in four locations in British Columbia provides insights into the ecological and social context, morphology, construction, and the first reported ages of these features. These data demonstrate the extent of traditional maricultural systems among coastal First Nations, and coupled with previously collected information on terrestrial management, challenges us to broaden our definition of “forager” as applied to Northwest Coast peoples. This study also highlights the value of combining diverse kinds of knowledge, including archaeological data, to understand the social and ecological contexts of traditional management systems.

Our knowledge of what the denizens of the animal kingdom are up to, especially when humans aren’t around, has steadily increased over the last 50 years. For example, we know now that animals use tools in their daily lives. Chimps use twigs to fish for termites; sea otters break open shellfish on rocks they selected; octopi carry coconut shell halves to later use as shelters....The latest discovery has taken this assessment to new heights, literally. A team of researchers led by Mark Bonta and Robert Gosford in northern Australia has documented kites and falcons, colloquially termed “firehawks,” intentionally carrying burning sticks to spread fire. While it has long been known that birds will take advantage of natural fires that cause insects, rodents and reptiles to flee and thus increase feeding opportunities, that they would intercede to spread fire to unburned locales is astounding.....The worldwide attention given to the firehawks article provides an opportunity to explore the double standard that exists concerning the acceptance of Traditional Knowledge by practitioners of Western science.

Historical ecology can provide insights into the long-term and complex relationships between humans and culturally important species and ecosystems, thereby extending baselines for modern management. We bring together paleoecological, archaeological, and modern clam records to explore the relationship between humans and butter clams (Saxidomus gigantea) throughout the Holocene in the northern Salish Sea of British Columbia, Canada. We compare butter clam size and growth patterns from different temporal, environmental, and cultural contexts spanning 11,500 y to present. Butter clam size and growth were restricted in early postglacial times but increased over the next few millennia. During the early-Late Holocene, humans took increasing advantage of robust clam populations and after 3.5 ka, began constructing clam gardens (intertidal rock-walled terraces). Environmental and cultural variables, including coarse substrate, stabilized sea surface temperature, and the presence of a clam garden wall, increased clam growth throughout the Holocene. Measurements of clams collected in active clam gardens and deposited in middens suggest that clam gardens as well as other mariculture activities enhanced clam production despite increased harvesting pressure. Since Eu-ropean contact, decline of traditional management practices and increases in industrial activities are associated with reduced clam size and growth similar to those of the early postglacial clams. Deeper-time baselines that more accurately represent clam population variability and allow us to assess magnitudes of change throughout time as well as the complex interactions among humans and clams are useful for modern marine resource management. historical ecology | clam gardens | traditional resource management | Northwest Coast | paleoecology O ver the millennia, many peoples worldwide developed intimate knowledge of, and relationships with, particularly valued species of plants and animals (1). Tracking the development of these long-term human-species relationships requires temporally grounded records that provide insights into both the cultural and ecological sides of this equation. For instance, the archaeological faunal record can provide detailed information on the ecological and cultural effects of human-species interactions (2-5), whereas the paleoecological record can provide insights into species ecology in the absence of significant human intervention (6-8). Taken together, these 2 records can offer a powerful lens through which to assess coupled social-ecological systems over broad spatial and temporal scales and can help establish ecological baselines for modern management (8-12). On the Northwest Coast of North America, clams are a valued cultural species (13, 14) with widespread importance that is reflected in origin stories, rituals, language, and in the kilometers of deep and ancient shell middens that line the coastline (15, 16). Detailed archaeological and ethnographic research indicates that clams, especially butter clams (Saxidomus gigantea) and littleneck clams (Leukoma staminea), were eaten in abundance both seasonally and year round (17) and both fresh and preserved. These species were a reliable, abundant, and easily harvested source of food (13, 18) that could be tended to increase abundance by applying various traditional cultivation techniques. One such technique, the building of rock-walled intertidal terraces called "clam gardens," expanded and enhanced clam habitat and thus, clam production (14, 16, 19, 20). Complimenting the archaeological and ethnographic records, studies of subfossil and fossil bivalves on the Northwest Coast have provided significant insights into the region's paleoecol-ogy. Such data have been used for reconstructing both pre-human (21) and recent historical ecological conditions (22, 23). To our knowledge, no studies have combined both the archaeological and paleoecological marine bivalve records to fully explore the long-term relationships among humans and clams. In this paper, we investigate the historical ecology of butter clams throughout the Holocene along the northern coast of Quadra Island, Salish Sea, British Columbia (Fig. 1) through analyses of the paleoecological, archaeological, and contemporary ecological records. Together, these records encompass 11,500 y of history-a period that spans the time before extensive human settlement to Significance Climate change, habitat loss, and overharvesting are threatening coastal ecosystems worldwide. A less widely recognized threat is the decline in Indigenous mariculture practices. These practices, such as building of clam gardens, structured coastal ecosystems for millennia. Teasing out the dynamic and intertwined relationships between humans and culturally valued species, such as clams, requires long-term paleoecological and archaeological records. These records are requisite for creating meaningful management targets and for applying traditional mariculture practices, such as the tending of clam gardens, to increase the productivity and sustainability of our foods today. Documenting these interactions between humans and coastal ecosystems, such as we have done here, also counteracts the erasure of the long-term connections of Indigenous peoples to their lands and seas.

Historical ecology can provide insights into the long-term and complex relationships between humans and culturally important species and ecosystems, thereby extending baselines for modern management. We bring together paleoecological, archaeological, and modern clam records to explore the relationship between humans and butter clams (Saxidomus gigantea) throughout the Holocene in the northern Salish Sea of British Columbia, Canada. We compare butter clam size and growth patterns from different temporal, environmental, and cultural contexts spanning 11,500 y to present. Butter clam size and growth were restricted in early postglacial times but increased over the next few millennia. During the early-Late Holocene, humans took increasing advantage of robust clam populations and after 3.5 ka, began constructing clam gardens (intertidal rock-walled terraces). Environmental and cultural variables, including coarse substrate, stabilized sea surface temperature, and the presence of a clam g...

While there is increasing recognition among archaeologists of the extent to which non-agricultural societies have managed their terrestrial ecosystems, the traditional management of marine ecosystems has largely been ignored. In this paper, we bring together Indigenous ecological knowledge, coastal geomorphological observations, and archaeological data to document how Northwest Coast First Nations cultivated clams to maintain and increase productivity. We focus on “clam gardens,” walled intertidal terraces constructed to increase bivalve habitat and productivity. Our survey and excavations of clam gardens in four locations in British Columbia provide insights into the ecological and social context, morphology, construction, and first reported ages of these features. These data demonstrate the extent of traditional maricultural systems among coastal First Nations and, coupled with previously collected information on terrestrial management, challenge us to broaden our definition of “f...