Climate change and pulse migration: intermittent Chugach Inuit occupation of glacial fiords on the Kenai Coast, Alaska

Abstract

For millennia, Inuit peoples of the Arctic and Subarctic have been challenged by the impacts of climate change on the abundance of key subsistence species. Responses to climate-induced declines in animal populations included switching to alternative food sources and/or migrating to regions of greater availability. We examine these dynamics for the Chugach Inuit (Sugpiat) people of southern coastal Alaska by synthesizing a large body of evidence from archeological sites, including radiocarbon dates and archaeofaunal assemblages, and by applying contemporary knowledge of glaciomarine ecosystems, spatial patterns of resource richness, and ocean-climate induced regime shifts in the Gulf of Alaska. We hypothesize that Chugach groups migrated from Cook Inlet and Prince William Sound to the Kenai Peninsula during periods of low sea surface temperatures (SSTs) to harvest harbor seals, which were seasonally aggregated near tidewater glaciers during pupping season, as well as piscivorous seabirds, Pacific cod, and other species that thrive under cool ocean conditions. During warming phases, the Chugach returned to Cook Inlet and Prince William Sound to fish for salmon and other species that abound during higher SSTs. Drivers of this coupled human-natural system of repeated (pulse) migration include the Pacific Decadal Oscillation (PDO), the dominant pattern of sea surface temperatures in the North Pacific that has been shown to generate step-like regime shifts in the marine food web; and coastal glaciers that structure the functioning of fiord ecosystems and support high levels of biological productivity. The culturally-constructed Chugach niche in the glaciomarine habitat of the Gulf of Alaska was based on intergenerationally transmitted ecological knowledge that enabled a resilient, mobile response to climate and resource variation.

Laaxaayík, Near the Glacier: Indigenous History and Ecology at Yakutat Fiord, Alaska

“…In environmental archaeology, long-term processes of human colonization, adaptation, and modification of ecosystems can be modeled by the theory of niche construction (Oetelaar and Oetelaar 2007;Laland and O'Brien 2010;Reide 2011;Lightfoot et al 2013;Spengler 2014;Lullfitz et al 2017;Fitzhugh et al 2019;Crowell and Arimitsu 2023). The underlying concept of human niche construction is from evolutionary ecology, where niche refers to the interrelationships of an organism with its habitat and biotic community through exchanges of energy and matter (Lewontin 1983;Kylafis and Loreau 2011;Odling-Smee et al 2013).…”

“…Cooler sea surface temperatures occur during weaker periods of the Pacific Decadal Oscillation and also prevailed during the Little Ice Age; cooler sea surface temperatures are associated with high productivity regimes for forage fishes, sea mammals, and sea birds (Hirons et al 2001;Benson and Trites 2002;Finney et al 2002;Maschner et al 2008;Misarti et al 2009). Late eighteenth century sea surface temperatures were 2°-3°C colder in the central Gulf of Alaska than at present (Helser et al 2018), and faunal remains from the Early Contact Village, a Sugpiat site on the Kenai Peninsula that was occupied in about 1800 CE, were dominated by harbor seal, harbor porpoise, sea lion, murre, puffin, Pacific cod, rockfish, and other species that thrive in colder water (Crowell et al 2008;Crowell and Arimitsu 2023). A similar suite of species, although lacking seabirds, is present at the late Little Ice Age archaeological site of Tlákw.aan in Yakutat Bay (chapter 5,this volume).…”