Climate Change and Indigenous Subsistence in the Thompson River Watershed (British Columbia) in the Late Holocene

The Indigenous peoples of the Thompson River watershed on the northern Columbia Plateau traditionally subsisted in winter on dried salmon, dried roots and berries from upland meadows, and game. A summed probability distribution (SPDF) based on 54 radiocarbon ages from twenty-eight winter villages and summer fishing camps along that river exhibits volatile activity in anti-phase with an SPDF derived from 77 radiocarbon ages from twenty-six sites in the neighbouring uplands in the 2500–500 cal BP interval. Activity levels on the riverbanks decline after ∼2000 cal BP, increase rapidly from ∼1600 cal BP to ∼1350 cal BP, fall dramatically in the next century, then rise again after ∼700 cal BP, echoing patterns at other upriver fisheries on the northern Columbia plateau. Periods of increased activity on the Thompson riverbank are linked to robust runs of sockeye salmon, prompted by cooler/wetter phases of regional climate, and marked by higher lake levels, glacial advances, and increased rates of coastal upwelling in the northeast Pacific. Less reliable salmon harvests in the intervening periods are indicated by increases in activity in the uplands, with a concomitant greater reliance on roots and game in the local diet.