Q&A: Recent Research on Southern Beaufort Sea Polar Bears Active
Polar bears are found throughout the circumpolar Arctic and roam across miles of sea ice and land. There are 19 recognized subpopulations of polar bears across the Arctic with two in Alaska: the Chukchi Sea and the Southern Beaufort Sea. The sea ice habitat of these subpopulations is changing with substantial recent declines in the extent of sea ice off the coast of Alaska. These changes are leading polar bears to spend more time on land, which increases the chances for human-bear interactions that may be harmful for bears and people.
Return to USGS Alaska Q&A Series
Each spring, the USGS Alaska Science Center polar bear research team conducts surveys and research on the North Slope of Alaska, focusing on the Southern Beaufort Sea subpopulation. Even though it’s spring when the work is conducted, the northern coast of Alaska is still gripped by snow, ice, and frigid temperatures during this time. This past spring, Todd Atwood – a research wildlife biologist with the USGS Alaska Science Center – wrapped up the third year of field work on a joint U.S. – Canada effort to develop an updated estimate of abundance for the Southern Beaufort Sea and Northern Beaufort Sea polar bear subpopulations.
Additionally, several new publications involving Todd and colleagues from agencies, universities, and industry have been published that address the population implications of the continued decline in Arctic sea ice, the preferred habitat for polar bears. These publications also evaluate what short-term mitigation measures are likely needed to reduce impacts as more polar bears come on shore to forage and build dens to birth cubs. In a recent perspective essay in the Wildlife Professional magazine, Todd discusses what long-term studies reveal about polar bear ecology but also the short-term management challenges as sea ice declines. Here, we talk about that essay, the 2022 spring field season, and what’s next for the USGS polar bear research program that focuses on the Southern Beaufort Sea subpopulation of bears.
How did the spring 2022 field season go? It was a late spring, so was the sea ice in a better condition for polar bears?
The field season was a success, largely because the pack ice was mostly cohesive throughout the 5-week effort. Since 2016, the spring ice conditions have been highly variable—in some years, we’ve encountered vast stretches of intact ice, while in other years we’ve had to navigate highly fragmented ice and open water. The ice conditions dictate bear distribution and where we can safely land the helicopter. In bad ice years, we occasionally must forego sampling a bear because we have nowhere to safely land. This year, we were able to sample nearly every bear we encountered due to the relatively good ice conditions.
When will the new population estimate for the Southern Beaufort Sea subpopulation be available and do you expect it to differ from the recent USGS estimates from 2001-2016?
The new abundance estimate should be released in 2024. We just finished our 3rd field season and will probably add one more year (2023) before wrapping up the sampling effort. The result will be abundance estimates for 2019-2022. This joint U.S. – Canada study is an impressive effort that will also make use of Indigenous Knowledge (IK) of polar bears, provided by residents of coastal Arctic communities, in the analytical framework. The incorporation of IK in the analysis will be an important methodological advancement and should result in more robust abundance estimates.
Do I expect the new abundance estimates to differ from the most recent estimates? That’s a tough one to answer. There’s a large body of research from the Southern Beaufort Sea subpopulation that supports a large decline in abundance in the mid-2000s, followed by apparent stability. Based on the sea ice conditions over the last 4-5 years, I won’t be surprised if the new abundance estimates are similar to the most recent USGS estimate, which is from 2015. In other long-studied subpopulations, like Western Hudson Bay, abundance has declined in a stair-step fashion, with periods of decline followed by periods of stability. We expect to see a similar pattern for the Southern Beaufort Sea subpopulation if sea ice continues to decline.
Recent papers that you’ve been involved with address our understanding of short-term impacts to polar bears such as if dens are close to industrial development, if bears use land around military installations more often than other land, and if high winds and melting sea ice trigger movement of bears to land. Why is it important to examine these potential short-term impacts?
The loss of sea ice habitat due to a warming climate is the primary threat to the long-term persistence of polar bears. Mitigating that threat has proved to be difficult due to our inability to reduce greenhouse gas emissions. But even if we were able to substantially reduce greenhouse gas emissions today, the recovery of sea ice habitat would be delayed for a decade or two because of the amount of greenhouse gases already present in our atmosphere. Our research suggests that managing short-term impacts to subpopulations, like threats posed by various types of human activities, should be part of a two-pronged strategy for polar bear conservation. That is, until sea ice loss is stabilized, identifying and mitigating short-term impacts may serve to slow the rate of population declines, and thereby improve the prospects of viable polar bear populations when sea ice habitats can be recovered. Some of these short-term impacts are summarized in the Wildlife Professional magazine article.
What are the plans for next year’s field work?
In 2023, we’ll continue our spring sampling in support of the joint U.S. – Canada study to estimate abundance of the Southern Beaufort Sea and Northern Beaufort Sea subpopulations. We’ll be staging out of two logistical bases: Utqiağvik, where we partner with colleagues from the North Slope Borough Department of Wildlife Management, and Deadhorse, which is the gateway to Alaska’s Arctic oil fields. We’ll spend about 2-3 weeks at each base and search for bears on the sea ice up to 90 miles from the coast. We’ll sample bears using biopsy darts, which are projectiles fired from a dart gun that collect a very small skin sample. DNA from the skin sample is used to derive a genetic ID of each sampled individual. Genetic ID’s are then used as “marks” in a mark-recapture statistical analysis to estimate abundance. Our colleagues from the North Slope Borough will also continue their collection of polar bear DNA from snow tracks. Environmental DNA, or eDNA, is genetic material obtained from samples like water, soil, or snow. Biologists from the North Slope Borough have made some exciting progress in isolating polar bear DNA from snow tracks, and those samples will be used to bolster the genetic ID data set. These new technologies are helpful as we continue to have spring field seasons where declines in sea ice make traditional captures difficult.
Polar Bear Research
Polar bears are found throughout the circumpolar Arctic and roam across miles of sea ice and land. There are 19 recognized subpopulations of polar bears across the Arctic with two in Alaska: the Chukchi Sea and the Southern Beaufort Sea. The sea ice habitat of these subpopulations is changing with substantial recent declines in the extent of sea ice off the coast of Alaska. These changes are leading polar bears to spend more time on land, which increases the chances for human-bear interactions that may be harmful for bears and people.
Return to USGS Alaska Q&A Series
Each spring, the USGS Alaska Science Center polar bear research team conducts surveys and research on the North Slope of Alaska, focusing on the Southern Beaufort Sea subpopulation. Even though it’s spring when the work is conducted, the northern coast of Alaska is still gripped by snow, ice, and frigid temperatures during this time. This past spring, Todd Atwood – a research wildlife biologist with the USGS Alaska Science Center – wrapped up the third year of field work on a joint U.S. – Canada effort to develop an updated estimate of abundance for the Southern Beaufort Sea and Northern Beaufort Sea polar bear subpopulations.
Additionally, several new publications involving Todd and colleagues from agencies, universities, and industry have been published that address the population implications of the continued decline in Arctic sea ice, the preferred habitat for polar bears. These publications also evaluate what short-term mitigation measures are likely needed to reduce impacts as more polar bears come on shore to forage and build dens to birth cubs. In a recent perspective essay in the Wildlife Professional magazine, Todd discusses what long-term studies reveal about polar bear ecology but also the short-term management challenges as sea ice declines. Here, we talk about that essay, the 2022 spring field season, and what’s next for the USGS polar bear research program that focuses on the Southern Beaufort Sea subpopulation of bears.
How did the spring 2022 field season go? It was a late spring, so was the sea ice in a better condition for polar bears?
The field season was a success, largely because the pack ice was mostly cohesive throughout the 5-week effort. Since 2016, the spring ice conditions have been highly variable—in some years, we’ve encountered vast stretches of intact ice, while in other years we’ve had to navigate highly fragmented ice and open water. The ice conditions dictate bear distribution and where we can safely land the helicopter. In bad ice years, we occasionally must forego sampling a bear because we have nowhere to safely land. This year, we were able to sample nearly every bear we encountered due to the relatively good ice conditions.
When will the new population estimate for the Southern Beaufort Sea subpopulation be available and do you expect it to differ from the recent USGS estimates from 2001-2016?
The new abundance estimate should be released in 2024. We just finished our 3rd field season and will probably add one more year (2023) before wrapping up the sampling effort. The result will be abundance estimates for 2019-2022. This joint U.S. – Canada study is an impressive effort that will also make use of Indigenous Knowledge (IK) of polar bears, provided by residents of coastal Arctic communities, in the analytical framework. The incorporation of IK in the analysis will be an important methodological advancement and should result in more robust abundance estimates.
Do I expect the new abundance estimates to differ from the most recent estimates? That’s a tough one to answer. There’s a large body of research from the Southern Beaufort Sea subpopulation that supports a large decline in abundance in the mid-2000s, followed by apparent stability. Based on the sea ice conditions over the last 4-5 years, I won’t be surprised if the new abundance estimates are similar to the most recent USGS estimate, which is from 2015. In other long-studied subpopulations, like Western Hudson Bay, abundance has declined in a stair-step fashion, with periods of decline followed by periods of stability. We expect to see a similar pattern for the Southern Beaufort Sea subpopulation if sea ice continues to decline.
Recent papers that you’ve been involved with address our understanding of short-term impacts to polar bears such as if dens are close to industrial development, if bears use land around military installations more often than other land, and if high winds and melting sea ice trigger movement of bears to land. Why is it important to examine these potential short-term impacts?
The loss of sea ice habitat due to a warming climate is the primary threat to the long-term persistence of polar bears. Mitigating that threat has proved to be difficult due to our inability to reduce greenhouse gas emissions. But even if we were able to substantially reduce greenhouse gas emissions today, the recovery of sea ice habitat would be delayed for a decade or two because of the amount of greenhouse gases already present in our atmosphere. Our research suggests that managing short-term impacts to subpopulations, like threats posed by various types of human activities, should be part of a two-pronged strategy for polar bear conservation. That is, until sea ice loss is stabilized, identifying and mitigating short-term impacts may serve to slow the rate of population declines, and thereby improve the prospects of viable polar bear populations when sea ice habitats can be recovered. Some of these short-term impacts are summarized in the Wildlife Professional magazine article.
What are the plans for next year’s field work?
In 2023, we’ll continue our spring sampling in support of the joint U.S. – Canada study to estimate abundance of the Southern Beaufort Sea and Northern Beaufort Sea subpopulations. We’ll be staging out of two logistical bases: Utqiağvik, where we partner with colleagues from the North Slope Borough Department of Wildlife Management, and Deadhorse, which is the gateway to Alaska’s Arctic oil fields. We’ll spend about 2-3 weeks at each base and search for bears on the sea ice up to 90 miles from the coast. We’ll sample bears using biopsy darts, which are projectiles fired from a dart gun that collect a very small skin sample. DNA from the skin sample is used to derive a genetic ID of each sampled individual. Genetic ID’s are then used as “marks” in a mark-recapture statistical analysis to estimate abundance. Our colleagues from the North Slope Borough will also continue their collection of polar bear DNA from snow tracks. Environmental DNA, or eDNA, is genetic material obtained from samples like water, soil, or snow. Biologists from the North Slope Borough have made some exciting progress in isolating polar bear DNA from snow tracks, and those samples will be used to bolster the genetic ID data set. These new technologies are helpful as we continue to have spring field seasons where declines in sea ice make traditional captures difficult.