Seal Science: Establishing Baselines: Data Gaps in Harbor Seal Research

Seal Science: Establishing Baselines: Data Gaps in Harbor Seal Research

Posted By:
Kathy Dye
Kathy Dye
Published On: April 19th, 2023

This article is one of eight in a series of outreach materials funded through a partnership between Sealaska Heritage Institute (SHI) and the Indigenous People’s Council for Marine Mammals (IPCoMM) on harbor seal conservation and subsistence harvesting.

While residents and visitors of coastal Alaska may have to search to see a humpback whale or a blue heron, a less elusive and appropriately-named harbor seal can often be found lounging near the docks. Like much Alaskan wildlife, harbor seals blend into Alaska’s unique urban environments seamlessly, making them feel almost pedestrian. While harbor seals are one of North America’s most common marine mammals, their sustained history of cultural and ecological importance in Alaska make them anything but ordinary. Their widespread nature makes them uniquely important across a diverse range of Alaska’s coastal Indigenous communities.

These playful pinnipeds are ecological, cultural, and economic keystones, and the more we supplement thousands of years of traditional Indigenous science with Western science, the more we can reduce the threats against them.

While you may see large groups of harbor seals hauled out on tidewater glacier fronts, they’re typically solitary in the water, where they spend the majority of their time. This makes counting populations difficult, as seals most commonly haul out when they have pups and molt during the spring and summer months. With seasonal fluctuations in population numbers, establishing a baseline census for harbor seal populations is an ongoing challenge for the National Oceanic and Atmospheric Administration (NOAA).

In 2010 a partnership with the Alaska Native Harbor Seal Commission allowed NOAA to identify 12 harbor seal stocks in Alaska, comprising the majority of the 16 stocks identified nationwide. Stocks are defined as a group of individuals of the same species who regularly occupy the same environment and interbreed. Since harbor seals are non-migratory and have a relatively small geographic range close to land, this means that each of Alaska’s stocks have slight differences in their diets, behaviors, and genetics. For example, Lake Iliamna is home to one of very few freshwater harbor seal populations, who have different diets, seasonal behavior, and coats than their tidewater glacier cousins in Southeast. Their remote locations and largely underwater lifespans mean that while these stocks have been identified, there is a wealth of stock-specific knowledge that is yet to be investigated and recorded by Western scientists.

As these stocks are spread throughout Alaska’s coastlines, they have been important parts of the food, art, and culture of multiple Indigenous groups. While terrestrial life like plants and land mammals differ wildly across Alaska’s many different terrains, harbor seals have been a common element between Yup’ik, Alutiiq, Dena’ina, Eyak, Unangax̂, Sugpiaq, Tlingit, Haida, and Tsimshian subsistence lifestyles for as long as seals and people have shared these environments. The close relationships between subsistence hunters and the land they steward means that while Western researchers have had difficulty establishing confident baselines for populations and behaviors, traditional ecological knowledge has been vital for understanding changes in trends. When cruise ship tourism increased rapidly at the turn of the century, Tlingit hunters in Yakutat noticed a decline in seal numbers in Disenchantment Bay, leading to a NOAA study showing that pups leave ice floes as a response when boats get too close, causing thermal stress. Due to this research, there is legislation in place to keep boats 500 m away from hauled out seals.

It is only through the knowledge of subsistence hunters that Western scientists have even begun to understand the harbor seal stocks that Alaska’s Indigenous peoples have been researching, hunting, and living with for thousands of years. Through shared interest in conservation of this keystone species, combined efforts of Western scientists and Native cultural scholars are necessary to understand how to understand and preserve this species.

References/Additional Resources

“Harbor Seal.” NOAA Species Directory.,the%20western%20North%20Atlantic%20stocks.

“Marine Mammal Stock Assessments.” NOAA, 24 Jan. 2023,,MMPA%20was%20amended%20in%201994.

Van Lanen, James. “Iliamna Lake Seals: Local and Scientific Understanding.” Alaska Fish & Wildlife News, May 2012.

Jansen et al. “Reaction of Harbor Seals to Cruise Ships.” The Journal of Wildlife Management, vol. 74, no. 6, pp. 1186-1194.  

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