Walrus Research

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The Pacific walrus (Odobenus rosmarus divergens) is one of 4 marine mammal species managed by the U.S. Department of Interior. The USGS Alaska Science Center conducts long–term research on Pacific walruses to inform local, state, national and international policy makers regarding conservation of the species and its habitat. The goal of our current research efforts is to refine and enhance models to project the future status of the Pacific walrus in the rapidly changing Arctic environment.

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Tracking Walrus by Satellite

The USGS conducts research to understand how continued summer sea ice loss affects the walrus population. To help answer these questions, USGS researchers  attached satellite radio tags to walruses to study changes in their movements and foraging habits as a consequence of reduced sea ice over the continental shelf. 

Image: Scientists Preparing to Radio-Tag Walruses

Scientists prepare to radio-tag walruses in the Chukchi sea to track movements as sea ice is reduced in the region.
(Credit: U.S. Geological Survey. Public domain.)

Walrus radio-tracking in the Chukchi Sea 2015: USGS Alaska Science Center researchers attached 39 satellite radio-tags to walruses in the northeastern Chukchi Sea, July 14-15 to track the movement patterns and foraging behaviors of walruses within areas of offshore sea ice. 

Project Purpose:  The retreat of sea ice beyond the continental shelf in the past seven years represents a step change in the summer habitat for the Pacific walrus and our observations of their behavior under these conditions of extreme summer ice minimums is providing a glimpse into their potential response to future summertime sea ice loss. The loss of summer sea ice in the Chukchi Sea is also increasing opportunities for human activities in the Arctic, such as shipping and oil and gas activities.

 

 

 

 

 

Forecasting Pacific walrus responses to climate change

Walrus Female And calf Up Close From The Side

Female walrus and calf in the Chukchi Sea 
(Credit: Sarah Sonsthagen, U.S. Geological Survey. Public domain.)

The Pacific walrus is a benthic feeding, ice-associated pinniped that ranges over the continental shelves of the Bering and Chukchi seas.  The extent of summer sea ice in the Chukchi Sea has decreased substantially in recent years and this trend is projected to continue.  Changes in the distribution of seasonal sea ice will likely affect walrus distribution and behavior and could affect the status of this population.  Based on this and concerns about the effects of large-scale industrial developments that are expected to take place in walrus habitat, the U.S. Fish and Wildlife Service has recently designated this the Pacific walrus as warranted for listing under the Endangered Species Act, with a final decision scheduled for 2017.  Department of Interior agencies need information on likely responses of walruses to climate change and other potential impacts as a basis for management of this trust species.  As a part of the USGS Changing Arctic Ecosystem Initiative, this research is focused on developing a comprehensive approach for forecasting status of the Pacific walrus population under changing climate scenarios.  We are developing and integrating bioenergetic and population dynamics models to provide mechanistic linkages between forecasted changes in sea ice and benthic prey and population level consequences for walruses.  There is almost no existing information about bioenergetic or demographic parameters for walruses, there have been no previous attempts to model their bioenergetics, and existing population models are rudimentary.  Technology for long-term monitoring of individual walruses is not currently available and other approaches for estimating the necessary parameters must be developed.

Quantification of walrus diet using DNA from fecal material

The distribution and availability of sea-ice has changed dramatically in recent years, causing Pacific walruses to change their distribution and areas of foraging during summer and autumn months. To better understand the consequences of these new behaviors to walrus energetics, body condition, and potentially survival and reproduction, we must understand what prey items are important to walruses and the availability and caloric contribution of those prey items to the walrus diet. Toward this end, we are collecting walrus fecal matter from ice floes across the Chukchi and Bering Seas, and identifying prey taxa within feces by use of a new DNA sequencing approach. This approach to assessing walrus diet will aid in the identification of dominant prey taxa and uncover prey taxa that occur in low abundance resulting in a more complete dietary profile. Overlaying these dietary profiles with key foraging areas and prey biomass distributions will improve our ability to forecast how walruses may respond to a changing Arctic.

Additional Research

  • An age-structure survey to estimate current demographics of the Pacific walrus
  • Walrus seasonal distribution and habitat use in the eastern Chukchi Sea
  • Modeling walrus-habitat associations and foraging energetics