Marine Wildlife and Habitats

Science Center Objects

The USGS conducts research on marine wildlife, habitats, and processes to provide science to inform our partners as they make decisions relative to species status, resource use, and human activities.

Return to Wildlife, Fish and Habitats

Polar Bears

Polar bear mother and two cubs on the Beaufort Sea ice.

Polar bear mother and two cubs on the Beaufort Sea ice. (Credit: Steven Amstrup, USGS, Alaska Science Center. Public domain.)

The long-term persistence of polar bears is linked to the health of the Arctic marine ecosystem, particularly the availability of sea ice habitat. Polar bears rely on sea ice to meet several key life history needs including accessing prey, searching for mates, and establishing maternal dens. However, the Arctic is experiencing a warming trend that is driving pronounced changes in sea ice extent and structure. Over the past 25 years, summer sea ice cover has declined by over half a million square miles. Arctic warming, and declines in sea ice habitat for polar bears, will likely continue for several decades given the current trends in global greenhouse gas emissions.


Nearshore Marine Ecosystems

Nearshore marine habitats are strongly influenced by adjacent terrestrial and oceanic biomes, including the numerous human impacts affecting each. Nearshore systems also are the habitats in which most people interact with marine environments, and they have high economic, recreational, and ecological values. Nearshore ecosystems support discrete food webs that originate with eelgrass and seaweeds, include benthic invertebrate and fish consumers, and culminate in a unique suite of top predators, including sea otters. Ongoing research addresses the natural and human-induced variation in nearshore ecosystems.


Pacific walrus hauled out on ice

Pacific walrus hauled out on ice. Middle walrus has satellite tag implanted in back. (Public domain.)


The Pacific walrus ranges throughout much of the Chukchi and Bering seas over an area equivalent to the combined areas of the western states of WA, OR, CA, ID, UT, and NV.  Walruses rely on sea ice as a platform to rest upon over the productive offshore habitats of the shallow continental shelves.  Here walruses forage on the seafloor for a wide range of invertebrates (primarily clams and marine worms) that depend on food fall from the upper water column.  Arctic sea ice is rapidly decreasing and causing shifts in prey production and changes to walrus distributions and activity budgets with unknown consequences to the walrus population.  These, and other stressors from increasing human activities in the Arctic, raise concerns over the future status of the species and the well-being of coastal indigenous peoples of the US and Russia where walruses are a major subsistence resource.


Seabirds and Forage Fish Ecology

A Tufted Puffin is flying near it's colony on Bogoslof Island

A Tufted Puffin is flying near its colony on Bogoslof Island (volcano) in the Aleutian Islands. (Credit: Ajay Varma, USGS. Public domain.)

Alaska's coastal and offshore waters provide foraging habitat for an estimated 100 million birds comprising more than 90 different species; from loons and sea ducks that nest inland, to petrels and puffins that breed on islands off shore. All these birds depend on the sea to provide a wide variety of food types including krill, forage fish, and squid. The availability of nesting habitat and suitable prey are important natural factors that regulate the distribution and abundance of marine birds. Seabird populations are also affected by human activities that have direct impacts (pollution, bycatch in fishing gear) and indirect effects (global warming alters food availability) on birds. In this project we attempt to quantify how natural variability in marine environments regulates seabird food supplies, so that we can better understand the additive impact of human activities on seabird foraging success and population dynamics.  


Habitat Dynamics

Each year the Arctic landscape transitions from a dark and frigid winter to a highly productive summer. Wildlife species synchronize their migrations and reproductive cycles to capitalize on the flourishing habitat conditions that accompany long summer days. However, natural weather variability as well as climate warming can influence the availability and quality of habitats during key stages of migration and reproduction. Satellite imagery and weather data document the dynamics of habitat conditions across the Arctic and help us improve our understanding of how weather and seasonality can affect wildlife movements and population fluctuations.


Quantitative Ecology

The Quantitative Ecology research program develops statistical models and methods of learning from data to better understand how both individual animals and animal populations respond to their environment.  Knowing how ecological processes influence key outcomes, such as animal behavior, foraging success, survival, and reproduction, provides vital insights into how populations have changed through time, and possibly how populations are likely to respond to ecosystem changes anticipated in the future.  Consequently, research results provide essential information to help manage and conserve wildlife populations.  Although research is focused on Arctic and sub-Arctic ecosystems, many products have broad applicability to other ecosystems.



Information about demographic parameters is essential for understanding wildlife population dynamics, assessing impacts, and managing wildlife populations.  As the rate of anthropogenic alteration and disturbance of Arctic environments accelerates, the need for methods to assess status and forecast responses of wildlife populations is becoming even more urgent.  The challenge is to develop methods that maximize precision, account for observational biases, and accurately quantify uncertainty, while maintaining efficiency and practicality in implementation.