Mar 14, 2016
Arctic animal populations are rapidly declining. Scientists at the Smithsonian’s Arctic Studies Center are working with indigenous observers and partner organizations around the circumpolar Arctic to explore why these populations are crashing and whether climate, habitat or human factors like overhunting practices may be contributing to these crashes. Arctic anthropologist Aron L. Crowell directs the Alaska Office of the Smithsonian’s Arctic Studies Center and is leading a project investigating the sudden and swift large-scale decline of harbor seal populations in coastal southern Alaska.
The Arctic Crashes project is an international collaborative study exploring the history of polar animal fluctuations and the shifting scientific, cultural, and public interpretations of human-animal interactions in the Arctic. Alaskan Native people of the Unnagax, Sugpiaq, and Tlingit communities rely on harbor seals in the Gulf of Alaska as their primary subsistence resource. Government-sponsored bounty hunting from 1927-1972 threatened these animals, but intense commercial hunting pressure precipitated a population decline in the 1960s. Despite the efforts of conservationists and governmental organizations, including species protection under the Marine Mammal Protection Act of 1972, which eliminated all but Alaska Native subsistence hunting, harbor seal populations have crashed by more than 70% since the 1970s.
Before 1900, the Gulf of Alaska harbor seal population may have been over 500,000. Today there are about 150,000 harbor seals in the Gulf. Archaeological and historical information on human hunting patterns from A.D. 1500-1900, combined with Alaska Native oral traditions and contemporary observations, can provide a baseline for modeling long-term seal population history.
From 2011-2014, Aron conducted fieldwork in Yakutat Bay in southeastern Alaska, where harbor seals play an important role in the contemporary Tlingit subsistence economy. As modeled by the National Marine Fisheries Service the 150 seals that 400 Alaska Native residents hunt per year for consumption (down from about 250 seals per year in the 1990s), is within safe harvest levels for the species and is unlikely to be the culprit for the local or regional drop in harbor seal numbers.
Yakutat hunters focus much of their hunting at the spring ice floe seal rookery near Hubbard Glacier at the head of the bay. This way of hunting near the glacier goes back some 900 years, to when a much larger Hubbard Glacier filled the entire fjord. Over the centuries, as the glacier gradually retreated to its modern position, the Yakutat people built villages and hunting camps near its receding edge. Consequently, the oldest archaeological sites are located in the outer bay, while the most recent (from the late 19th century) are near its head. The Smithsonian’s Yakutat Seal Camps Project, funded by the National Science Foundation, relocated, mapped, and excavated at six of these locations. Seal bones preserved at the sites, along with barbed sealing harpoons, stone tools for scraping the hides, seal oil lamps and other tools, tell the story of human-seal interaction over many centuries.
The Yakutat Tlingit Tribe and many members of the community have been closely involved in this archaeological research, including high school students who worked with the Arctic Crashes field team on Knight Island in 2014. To record indigenous knowledge, Yakutat elders including George Ramos Sr., a lifelong seal hunter, and his wife Elaine Abraham, shared their deep knowledge of Yakutat history and dramatic changes that have taken place in the glaciers, landscape, and biome. Ramos has seen a major reduction of the seal population during his lifetime, and remembers that in the 1960s the ice was still “black with seals.” Crowell has interviewed and accompanied seal hunters including Jeremiah James, to record modern methods and perspectives.
“Yakutat Tlingit knowledge of these animals and their changing habitat is profound,” Aron observes. The Tlingit relationship to seals is “based on a belief in the essential personhood of both seals and of the glacier itself, which shelters the animals and provides them to the human community.”
While commercial and bounty-driven overhunting during the twentieth century was almost certainly a major factor in the harbor seal decline, nutritional stress due to climate-ecosystem cycles may be an important cause for its continuation. Oceanic warming since the end of the Little Ice Age (A.D. 1350-1900), particularly strong since the 1970s, is affecting the marine food web and limiting the availability of the most nutritious prey species for harbor seals. Aron and the Arctic Crashes team anticipate that human and natural causes for the seal crash are closely interlinked.
Michael Etnier, an expert is seal paleobiology at Portland State University, is analyzing seal bones and other fauna from a seal-hunting site the Arctic Studies Center team excavated in 2014. He plans to use stable isotope analysis to model marine productivity and water temperatures during the Little Ice Age period when this site was occupied. DNA analysis of the seal bones and comparison with modern samples provided by Yakutat seal hunters will examine how the seal population has changed over time. For instance, the current seal population may show genetic signatures of in-migration from other regions as Hubbard Glacier withdrew and Yakutat Bay opened up, creating one of the richest harbor seal habitats in southern Alaska.
While there is no simple answer to the big question of why Arctic animal crashes occur, Arctic Studies Center researchers and their colleagues are employing a broad, interdisciplinary approach that integrates human, climate, and ecosystem history, and joins scientific studies with indigenous community knowledge.