Q&A: Vessel Expedition for Estimates of Pacific Walrus Demography
Adult female and juvenile Pacific walruses reside in the northern Bering Sea and Chukchi Sea in the late spring and summer. In June of 2025, the U.S. Fish and Wildlife Service and the USGS will again conduct a walrus research expedition on the Research Vessel Norseman II. The expedition will depart from Nome, Alaska on June 2, 2025, and return to Nome on June 30, 2025. The research expedition will be supported by aerial surveys from Nome, Kotzebue and Utqiaġvik.
Return to USGS Alaska Q&A Series
The Pacific walrus ranges seasonally throughout much of the Bering and Chukchi seas in U.S. and Russian waters. Pacific walruses feed on organisms that live on the bottom of the sea floor, and they play a prominent role in the Arctic ecosystem. The Pacific walrus is also an extremely important cultural and subsistence resource to Alaska Native communities. The USGS and the U.S. Fish and Wildlife Service (USFWS) have focused on addressing existing data gaps. The two primary data gaps that scientists have focused on are population abundance (the number of Pacific walruses) and the trajectory of the population (increasing, stable, or decreasing).
During research expeditions from 2013–2017, the USFWS collected biopsy samples from walruses hauled-out on sea ice. Biopsy samples were used to identify individual animals with genetics. Analyses of these data generated the first abundance estimate since a 2006 aerial survey. This abundance estimate addressed the first data gap.
Additionally, the USGS collected information on population age structure during some of these same marine vessel expeditions in the Chukchi Sea. The age structure data were very informative and provided rigorous estimates of walrus survival rates.
The age structure data also addressed the second primary data gap: population trend over time. The age structure data provided scientists with an understanding of a multi-decade population decline of 60% over four decades. The population trajectory was stable as of 2015.
To reassess age structure and abundance of the Pacific walrus, the USGS, USFWS, and Alaska Native hunters are collaborating to conduct another round of marine vessel surveys that began in June of 2023. A third expedition is planned for summer of 2025.
In this Q&A, we talk with USGS research biologist William Beatty and USFWS biologist Irina Trukhanova about the research expeditions, how information about the expedition has been shared with important partners and communities, and what kinds of information will be collected during the expeditions.
Q: What is the role of Alaska Native Hunters in this expedition? How are they involved in the research?
William: Alaska Native hunters will again be joining the research expedition to provide insight into walrus behavior, sea ice dynamics and environmental conditions.
Irina: Alaska Native hunters are full research expedition participants. They play an integral part of the biopsy team and participate in the age structure surveys.
Q: What takes place during these expeditions and how do you find the walruses out at sea?
William: Similar to 2023, we will conduct a 4-week ship-based survey along the ice margin during June using walrus age and sex classification methods from previous surveys. We chose the early June starting date to increase the chance of encountering walrus groups before sea ice retreats north over deep waters. We also wanted to be consistent in terms of the timing with previous age structure surveys. We will have aerial support based out of Nome, Kotzebue or Utqiaġvik to locate walruses and direct the ship. A twin-engine aircraft will occasionally conduct a broad sweep of the ice margin to determine the general areas of walrus concentrations. The ship will then move along the ice margin and survey walrus groups.
Irina: While the age structure surveys are taking place, USFWS is leading a project to collect biopsy samples from walruses hauled-out on sea ice. We launch small skiffs from the ship to collect biopsy samples that are collected with a crossbow that deploys a dart that falls onto the ice or floats in the water (see diagram here). The dart is retrieved after walruses leave the area. We will use genetic markers to assign individual IDs to each walrus and use this information to estimate population size similarly to how it was done with data collected during the expeditions in 2013-2017.
Q: Who have you talked to about these expeditions? Are nearby communities aware that the expeditions are taking place?
Irina: We have provided information on these expeditions to many different groups thus far, including the Eskimo Walrus Commission (December 2024), North Slope Borough Planning Commission (October 2024), and the North Slope Borough Department of Wildlife Management (October 2024).
Q: Is this a two-year effort? How will results from the expedition be shared with hunters and communities in the Chukchi Sea region?
William: We plan to conduct another research expedition in 2026, which would be three years of data collection. Multiple years of data are important to provide an accurate view of age structure. We are sharing information from the expedition directly with the Eskimo Walrus Commission through their annual meeting.
Irina: At least three years of biopsy data is required for project success. The USFWS and USGS are seeking support for a third year of data collection in 2026.
Walrus Research
Q&A: Estimates of Abundance for Pacific Walrus
Adult female and juvenile Pacific walruses reside in the northern Bering Sea and Chukchi Sea in the late spring and summer. In June of 2025, the U.S. Fish and Wildlife Service and the USGS will again conduct a walrus research expedition on the Research Vessel Norseman II. The expedition will depart from Nome, Alaska on June 2, 2025, and return to Nome on June 30, 2025. The research expedition will be supported by aerial surveys from Nome, Kotzebue and Utqiaġvik.
Return to USGS Alaska Q&A Series
The Pacific walrus ranges seasonally throughout much of the Bering and Chukchi seas in U.S. and Russian waters. Pacific walruses feed on organisms that live on the bottom of the sea floor, and they play a prominent role in the Arctic ecosystem. The Pacific walrus is also an extremely important cultural and subsistence resource to Alaska Native communities. The USGS and the U.S. Fish and Wildlife Service (USFWS) have focused on addressing existing data gaps. The two primary data gaps that scientists have focused on are population abundance (the number of Pacific walruses) and the trajectory of the population (increasing, stable, or decreasing).
During research expeditions from 2013–2017, the USFWS collected biopsy samples from walruses hauled-out on sea ice. Biopsy samples were used to identify individual animals with genetics. Analyses of these data generated the first abundance estimate since a 2006 aerial survey. This abundance estimate addressed the first data gap.
Additionally, the USGS collected information on population age structure during some of these same marine vessel expeditions in the Chukchi Sea. The age structure data were very informative and provided rigorous estimates of walrus survival rates.
The age structure data also addressed the second primary data gap: population trend over time. The age structure data provided scientists with an understanding of a multi-decade population decline of 60% over four decades. The population trajectory was stable as of 2015.
To reassess age structure and abundance of the Pacific walrus, the USGS, USFWS, and Alaska Native hunters are collaborating to conduct another round of marine vessel surveys that began in June of 2023. A third expedition is planned for summer of 2025.
In this Q&A, we talk with USGS research biologist William Beatty and USFWS biologist Irina Trukhanova about the research expeditions, how information about the expedition has been shared with important partners and communities, and what kinds of information will be collected during the expeditions.
Q: What is the role of Alaska Native Hunters in this expedition? How are they involved in the research?
William: Alaska Native hunters will again be joining the research expedition to provide insight into walrus behavior, sea ice dynamics and environmental conditions.
Irina: Alaska Native hunters are full research expedition participants. They play an integral part of the biopsy team and participate in the age structure surveys.
Q: What takes place during these expeditions and how do you find the walruses out at sea?
William: Similar to 2023, we will conduct a 4-week ship-based survey along the ice margin during June using walrus age and sex classification methods from previous surveys. We chose the early June starting date to increase the chance of encountering walrus groups before sea ice retreats north over deep waters. We also wanted to be consistent in terms of the timing with previous age structure surveys. We will have aerial support based out of Nome, Kotzebue or Utqiaġvik to locate walruses and direct the ship. A twin-engine aircraft will occasionally conduct a broad sweep of the ice margin to determine the general areas of walrus concentrations. The ship will then move along the ice margin and survey walrus groups.
Irina: While the age structure surveys are taking place, USFWS is leading a project to collect biopsy samples from walruses hauled-out on sea ice. We launch small skiffs from the ship to collect biopsy samples that are collected with a crossbow that deploys a dart that falls onto the ice or floats in the water (see diagram here). The dart is retrieved after walruses leave the area. We will use genetic markers to assign individual IDs to each walrus and use this information to estimate population size similarly to how it was done with data collected during the expeditions in 2013-2017.
Q: Who have you talked to about these expeditions? Are nearby communities aware that the expeditions are taking place?
Irina: We have provided information on these expeditions to many different groups thus far, including the Eskimo Walrus Commission (December 2024), North Slope Borough Planning Commission (October 2024), and the North Slope Borough Department of Wildlife Management (October 2024).
Q: Is this a two-year effort? How will results from the expedition be shared with hunters and communities in the Chukchi Sea region?
William: We plan to conduct another research expedition in 2026, which would be three years of data collection. Multiple years of data are important to provide an accurate view of age structure. We are sharing information from the expedition directly with the Eskimo Walrus Commission through their annual meeting.
Irina: At least three years of biopsy data is required for project success. The USFWS and USGS are seeking support for a third year of data collection in 2026.
Walrus Research