Shellfish Harvest on the Coast of British Columbia: The Archaeology of Settlement and Subsistence through High-resolution Stable Isotope Analysis and Sclerochronology

Abstract

<p>In many interpretations of hunter-gatherer settlement systems, archaeologists have assumed implicitly or explicitly that a pattern of mobilitybased on seasonally-scheduled movements between different site locations waspracticed. This pattern of mobility is often characterized as a seasonal round, where different locations are used during specific times of the year for different purposes. An implication of this pattern of mobility is that short-term occupation sites are visited annually, approximately at the same time each year and longer-term residential sites can span multiple seasons. To interpret seasonality, indirect indicators are often used but the high-resolution methods presented in this study provide direct evidence of seasonal site occupation. The Pacific Northwest Coast provides an ideal landscape to examine seasonality since many of the staple resources, particularly salmon, were available on a seasonal basis. Contrary to longstanding assumptions of regular seasonal movement between sites, the analysis of shell samples from multiple archaeological sites from distinct regions in British Columbia show complex patterns of multi-seasonal occupation at smaller campsites and specific seasonal or multi-seasonal emphasis in occupation and/or shellfish harvest at longer-term residential sites.</p> <p>To identify patterns of shellfish harvest, stable oxygen isotope analysis and high-resolution sclerochronology were applied to the bivalve <em>Saxidomus gigantea</em> (butter clam). Combined with shell growth increment analysis to examine relative levels of harvest pressure, local rates of shellfish collecting are also interpreted. To examine regional variability in seasonality and resource use in British Columbia, three environmentally and historically distinct areas were selected spanning approximately 6000 years of history. These regions include the central coast in the tradition territory of the Heiltsuk, and two areas on the northern coast, specifically the Dundas Islands Group and Prince Rupert Harbour in the traditional territory of the Tsimshian. The results of the analysis show site-specific trends in shellfish harvesting on the central coast; a pattern which is not as clear on the northern coast. Sites on the Dundas Islands show multi-seasonal collection and a stronger emphasis on winter shellfish harvesting. The results also show that shellfish were harvested more intensively in the Dundas Islands area relative to the central coast. The pattern of seasonal shellfish harvesting on the mainland coast at village sites in Prince Rupert Harbour is similar to the pattern found at long-term residential sites on the central coast. With respect to the dietary importance of clams, another longstanding issue in Northwest Coast archaeology, the results show a mix of patterns including casual resource use at most campsites, intensive multi-season harvest in some regions and strategic multi-season harvest and spring consumption at some residential sites.</p>