STABLE ISOTOPES, SCLEROCHRONOLOGY AND 5000 YEARS OF HUMAN-ENVIRONMENTAL INTERACTIONS ON CANADA'S PACIFIC NORTHWEST COAST (Invited Presentation)

Shell midden sites on Canada’s Pacific Northwest coast are ideal for interpreting long-term human-environmental interactions since they contain millennial-scale records past sea surface conditions, shellfishing activities, and the records of past food consumption. The individual bivalve archives in shell middens contain information on day-to-day activities of past people, as well as high-resolution records of local sea surface temperature and salinity. Despite the ubiquity of shellfish remains, the dietary role of shellfish is unclear in archaeological contexts. While there an increase in the size and presence of shell middens over time, the role of shellfish in past diets, and in relation to local climate change, is not well understood. Previous research suggests that contributions from low-tropic marine sources were minimal when compared to high-tropic foods, such as salmon, and this is a trend the persists along the coast through time. However, the size and distribution of many shell middens suggests otherwise. Long-term environmental trends in the stable isotope and sclerochronological record of Saxidoums gigantea (butter clam) provide insight into past sea surface conditions, but also the season of shellfish collection, and harvest pressure on local bivalve populations. To understand the dietary contribution of shellfish in past diets, stable carbon and nitrogen data from dog bones provides insights into protein sources, reflecting broad trends in food consumption by both people and dogs. Combined with new radiocarbon dates, these lines of evidence provide a foundation to examine the contribution of shellfish resources to past diets over approximately 5000-years, and to critically assess changes in diet and subsistence over periods of climate change and stability on Vancouver Island in the traditional territory of the Coast Salish. Using ancillary lines of archaeological evidence, in conjunction with the results of geochemical analyses from bone and shell, this project expands upon the limits and potential of paleoenvironmental data in interpreting past human-environmental interactions.