Declines of Steller sea lion (Eumetopias jubatus) populations in the Aleutian Islands and Gulf of Alaska could be a consequence of physical oceanographic changes associated with the 1976-77 climate regime shift. Changes in ocean climate are hypothesized to have affected the quantity, quality, and accessibility of prey, which in turn may have affected the rates of birth and death of sea lions. Recent studies of the spatial and temporal variations in the ocean climate system of the North Pacific support this hypothesis. Ocean climate changes appear to have created adaptive opportunities for various species that are preyed upon by Steller sea lions at mid-trophic levels. The east-west asymmetry of the oceanic response to climate forcing after 1976-77 is consistent with both the temporal aspect (populations decreased after the late 1970s) and the spatial aspect of the decline (western, but not eastern, sea lion populations decreased). These broad-scale climate variations appear to be modulated by regionally sensitive biogeographic structures along the Aleutian Islands and Gulf of Alaska, which include a transition point from coastal to open-ocean conditions at Samalga Pass westward along the Aleutian Islands. These transition points delineate distinct clusterings of different combinations of prey species, which are in turn correlated with differential population sizes and trajectories of Steller sea lions. Archaeological records spanning 4000 yr further indicate that sea lion populations have experienced major shifts in abundance in the past. Shifts in ocean climate are the most parsimonious underlying explanation for the broad suite of ecosystem changes that have been observed in the North Pacific Ocean in recent decades.

No abstract

The Sanak Biocomplexity Project is a transdisciplinary research effort focused on a small island archipelago 50 km south of the Alaska Peninsula in the western Gulf of Alaska. This team of archaeologists, terrestrial ecologists, social anthropologists, intertidal ecologists, geologists, oceanographers, paleoecologists, and modelers is seeking to understanding the role of the ancient, historic, and modern Aleut in the structure and functioning of local and regional ecosystems. Using techniques ranging from systematic surveys to stable isotope chemistry, long-term shifts in social dynamics and ecosystem structure are present in the context of changing climatic regimes and human impacts. This paper presents a summary of a range of our preliminary findings.

A number of hypotheses have been proposed to explain the most recent decline (1977–2012) of Steller sea lions (SSL; Eumetopias jubatus) in the Gulf of Alaska and Aleutian Islands. We examined hypotheses about fisheries competition, environmental change, predation, anthropogenic effects and disease using observations of modern Aleut and archaeological, ethnohistoric and ethnographic data from the western Gulf of Alaska and Aleutian Islands. These data indicate that Steller sea lion numbers have declined and recovered repeatedly over the past 4500 years and were last at critically low numbers during the 1870s–1930s. Steller sea lions appear to have been more abundant during the cool periods – and lower during the warmer periods. Observations by local peoples, explorers, early government surveyors and biologists since the late 1800s suggest that low populations of SSL have been associated with high populations of Gadidae fishes (Pacific cod – Gadus macrocephalus and walleye pollock – Theragra chalcogramma) and are consistent with the ocean climate hypothesis to explain the decline of sea lions. They suggest that removals by people and killer whales (Orcinus orca) did not cause the sea lion declines, but could have compounded the magnitude of the decline as sea lion numbers approached low densities. Archaeological, anthropological and ethnohistorical analyses demonstrate that fluctuations have occurred in the North Pacific over hundreds to thousands of years and provide context for understanding the changes that occur today and the changes that will continue to occur in the future.

Sanak Island is the easternmost of the Aleutian Islands and was inhabited by the Aleut (Unangan) peoples for nearly 7000 years. The past few centuries of Sanak Island life for its Aleut residents can be summarized from ethnohistoric documents and extensive interviews with former residents as shifting local-global economic patterns beginning with the sea otter fur trade, followed by cod and salmon fishing, fox farming, and cattle ranching through waves of Russian, American, and Scandinavian authority and/or influence. As the industries changed and the island absorbed new peoples with new goals, Aleut identity and practices also changed as part of these shifting economic and social environments. Sanak Island was abandoned in the 1970s and although uninhabited today, Sanak Island is managed as an important land trust for the island's descendants that serves local peoples as a marine-scape rich in resources for Aleut subsistence harvesting and as a local heritage site where people draw on the diverse historical influences and legacies. Further, this move from an industrial heritage to contemporary local subsistence economies facilitated by a commercial fishing industry is a unique reversal of development in the region with broad implications for community sustainability among indigenous communities. We find that by being place-focused, rather than place-based, community sustainability can be maintained even in the context of relocation and the loss of traditional villages. This will likely become more common as indigenous peoples adapt to globalization and the forces of global change.