Q&A: Vessel Cruise 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 2024, the U.S. Fish and Wildlife Service and the USGS will again conduct a walrus research cruise on the Research Vessel Norseman II. The cruise will depart from Nome, Alaska on May 31, 2024, and return to Nome on June 28, 2024. The research cruise 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 rapid reduction of sea ice and increased periods of open water in the Arctic over the past few decades have real-time and future consequences to the Arctic ecosystem.
In recognition of future stressors to the Pacific walrus population that may result from reductions in summer sea ice, the USGS and the U.S. Fish and Wildlife Service (USFWS) have focused on addressing existing data gaps to understand and forecast the response of walruses to the rapid loss of sea ice. 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, decreasing).
During research cruises 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 cruises 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 second cruise is planned for summer of 2024.
In this Q &A, we talk with USGS research biologist William Beatty and USFWS biologist Irina Trukhanova about the research cruises, how information about the cruise has been shared with important partners and communities, and what kinds of information will be collected during the cruises. More information about the cruise can be found in a recorded talk from April 2023.
Q: What is the role of Alaska Native Hunters in this cruise? How are they involved in the research?
William: Alaska Native hunters will again be joining the research cruise to provide insight into walrus behavior, sea ice dynamics and environmental conditions.
Irina: Alaska Native hunters are full research cruise participants. They play an integral part of the biopsy team and participate in the age structure surveys.
Q: What takes place during these cruises 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 cruise 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 cruises in 2013-2017. In 2023, we also collected water, benthos and walrus fecal material to test for the presence of harmful algal toxins and better understand walrus diets.
Q: Who have you talked to about these cruises? Are nearby communities aware that the cruises are taking place?
Irina: We have provided information on these cruises to many different groups thus far, including the Eskimo Walrus Commission (December 2023), the Alaska Eskimo Whaling Commission (December 2023), North Slope Borough Planning Commission (October 2023), and the North Slope Borough Department of Wildlife Management (October 2023). More communication is planned in early 2024.
Q: Is this a two-year effort? How will results from the cruise be shared with hunters and communities in the Chukchi Sea region?
William: We plan to conduct a total of at least three years of this research cruise. Multiple years of data are important to provide an accurate view of age structure. We are sharing information from the cruise directly with the Eskimo Walrus Commission through their annual meeting.
Irina: At least three years of biopsy data is required for project success. USFWS and USGS are seeking support for a third research cruise in 2025 with aspirations for additional cruises in 2026 and 2027 if necessary.
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 2024, the U.S. Fish and Wildlife Service and the USGS will again conduct a walrus research cruise on the Research Vessel Norseman II. The cruise will depart from Nome, Alaska on May 31, 2024, and return to Nome on June 28, 2024. The research cruise 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 rapid reduction of sea ice and increased periods of open water in the Arctic over the past few decades have real-time and future consequences to the Arctic ecosystem.
In recognition of future stressors to the Pacific walrus population that may result from reductions in summer sea ice, the USGS and the U.S. Fish and Wildlife Service (USFWS) have focused on addressing existing data gaps to understand and forecast the response of walruses to the rapid loss of sea ice. 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, decreasing).
During research cruises 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 cruises 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 second cruise is planned for summer of 2024.
In this Q &A, we talk with USGS research biologist William Beatty and USFWS biologist Irina Trukhanova about the research cruises, how information about the cruise has been shared with important partners and communities, and what kinds of information will be collected during the cruises. More information about the cruise can be found in a recorded talk from April 2023.
Q: What is the role of Alaska Native Hunters in this cruise? How are they involved in the research?
William: Alaska Native hunters will again be joining the research cruise to provide insight into walrus behavior, sea ice dynamics and environmental conditions.
Irina: Alaska Native hunters are full research cruise participants. They play an integral part of the biopsy team and participate in the age structure surveys.
Q: What takes place during these cruises 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 cruise 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 cruises in 2013-2017. In 2023, we also collected water, benthos and walrus fecal material to test for the presence of harmful algal toxins and better understand walrus diets.
Q: Who have you talked to about these cruises? Are nearby communities aware that the cruises are taking place?
Irina: We have provided information on these cruises to many different groups thus far, including the Eskimo Walrus Commission (December 2023), the Alaska Eskimo Whaling Commission (December 2023), North Slope Borough Planning Commission (October 2023), and the North Slope Borough Department of Wildlife Management (October 2023). More communication is planned in early 2024.
Q: Is this a two-year effort? How will results from the cruise be shared with hunters and communities in the Chukchi Sea region?
William: We plan to conduct a total of at least three years of this research cruise. Multiple years of data are important to provide an accurate view of age structure. We are sharing information from the cruise directly with the Eskimo Walrus Commission through their annual meeting.
Irina: At least three years of biopsy data is required for project success. USFWS and USGS are seeking support for a third research cruise in 2025 with aspirations for additional cruises in 2026 and 2027 if necessary.