Survival and abundance of polar bears in Alaska’s Beaufort Sea, 2001–2016

Ecology and Evolution, Journal Year: 2021, Volume and Issue: 11(20), P. 14250 - 14267

Published: Sept. 23, 2021

Abstract The Arctic Ocean is undergoing rapid transformation toward a seasonally ice‐free ecosystem. As ice‐adapted apex predators, polar bears ( Ursus maritimus ) are challenged to cope with ongoing habitat degradation and changes in their prey base driven by food‐web response climate warming. Knowledge of bear environmental change necessary understand ecosystem dynamics inform conservation decisions. In the southern Beaufort Sea (SBS) Alaska western Canada, sea ice extent has declined since satellite observations began 1979 available evidence suggests that carrying capacity SBS for trended lower nearly two decades. this study, we investigated population Alaska's from 2001 2016 using multistate Cormack–Jolly–Seber mark–recapture model. States were defined as geographic regions, used location data satellite‐telemetered model transitions between states thereby explain heterogeneity recapture probabilities. Our results corroborate prior findings subpopulation experienced low survival 2003 2006. Survival improved modestly 2006 2008 afterward rebounded comparatively high levels remainder except 2012. Abundance moved concert throughout study period, declining substantially fluctuating variation around an average 565 (95% Bayesian credible interval [340, 920]) through 2015. Even though abundance was stable without sustained trend 2015, less abundant over period than at any time passage U.S. Marine Mammal Protection Act. potential recovery likely limited degree experienced, future reductions expected given current projections continued

Language: Английский

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Model sensitivity limits attribution of greenhouse gas emissions to polar bear demographic rates

Scientific Reports, Journal Year: 2025, Volume and Issue: 15(1)

Published: Feb. 10, 2025

Abstract Greenhouse gas emissions continue to increase and negatively affect sea ice conditions that polar bears rely on. It is therefore important better understand how specific levels bear demography. A recent study proposed a framework address this issue, but sensitivity decisions rules of the approach may limit its utility. We tested sensitive related concentration, choice subpopulation boundaries, modeling choices for in Chukchi Sea Southern Beaufort subpopulations. found number ice-free days, fasting when 10% reproductive females exhibited recruitment failure varied considerably depending on equally-valid versus those used existing study. Whereas previous suggested both subpopulations surpassed critical days recruitment, we threshold was never reached by only once decision considered. Our results suggest previously published too assumptions accurately evaluate impacts GHG demographic rates.

Language: Английский

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Bears of the World

Cambridge University Press eBooks, Journal Year: 2020, Volume and Issue: unknown

Published: Nov. 16, 2020

Bears have fascinated people since ancient times. The relationship between bears and humans dates back thousands of years, during which time we also competed with for shelter food. In modern times, come under pressure through encroachment on their habitats, climate change, illegal trade in body parts, including the Asian bear bile market. IUCN lists six as vulnerable or endangered, even least concern species, such brown bear, are at risk extirpation certain countries. poaching international these most threatened populations prohibited, but still ongoing. Covering all species worldwide, this beautifully illustrated volume brings together contributions 200 experts ecology, conservation status, management Ursidae family. It reveals fascinating long history interactions threats affecting charismatic species.

Language: Английский

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Observed and forecasted changes in land use by polar bears in the Beaufort and Chukchi Seas, 1985–2040

Global Ecology and Conservation, Journal Year: 2022, Volume and Issue: 40, P. e02319 - e02319

Published: Oct. 31, 2022

Monitoring changes in the distribution of large carnivores is important for managing human safety and supporting conservation. Throughout much their range, polar bears (Ursus maritimus) are increasingly using terrestrial habitats response to Arctic sea ice decline. Their increased presence coastal areas has implications bear-human conflict, inter-species interactions, bear health survival. We examined observed trends land use over three decades by southern Beaufort Sea (SB) Chukchi (CS) where have traditionally spent most year on ice. Using data from 408 adult females fitted with satellite radio-collars, we annual proportion coming onshore (hereafter referred as "percent bears") during summer ≥ 21 days, arrival departure dates, duration relationships metrics. then estimated future through 2040 extrapolating combining between projections an ensemble earth system models. The percent summering was correlated open water that occurred within population's range July October. As declined, ∼5–30% SB ∼10–50% CS > 30 days 60–70 both populations. a greenhouse gas emission scenarios adjustments faster than forecasted loss 50–62% 79–88% will spend 90–108 110–126 CS, respectively, 2040. varied little prior but diverged thereafter. Observed increases occupancy puts more proximity activities settlements longer durations while extending lack access primary prey. Because conflict one factors affecting conservation worldwide, mitigation interactions be component

Language: Английский

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Demographic risk assessment for a harvested species threatened by climate change: polar bears in the Chukchi Sea

Ecological Applications, Journal Year: 2021, Volume and Issue: 31(8)

Published: Sept. 28, 2021

Abstract Climate change threatens global biodiversity. Many species vulnerable to climate are important humans for nutritional, cultural, and economic reasons. Polar bears Ursus maritimus threatened by sea‐ice loss represent a subsistence resource Indigenous people. We applied novel population modeling‐management framework that is based on life history accounts habitat evaluate harvest the Chukchi Sea (CS) polar bear subpopulation. Harvest strategies followed state‐dependent approach under which new data were used update predetermined management interval. found strategy with starting total rate of 2.7% (˜85 bears/yr at current abundance), 2:1 male‐to‐female ratio, 10‐yr interval would likely maintain subpopulation abundance above maximum net productivity level next 35 yr (approximately three generations), our primary criterion sustainability. Plausible bounds 1.7–3.9%, where range reflects uncertainty due sampling variation, environmental model selection, differing levels risk tolerance. The undesired demographic outcomes (e.g., overharvest) was positively related rate, interval, projected declines in carrying capacity; negatively precision data. Results reflect several lines evidence CS has been productive recent years, although it uncertain how long this will last as continues. Our methods provide template balancing trade‐offs among protection, use, research investment, other factors. Demographic assessment become increasingly harvested species, like bears, exhibit spatiotemporal variation their response change.

Language: Английский

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The Role of Satellite Telemetry Data in 21st Century Conservation of Polar Bears (Ursus maritimus)

Frontiers in Marine Science, Journal Year: 2022, Volume and Issue: 9

Published: April 14, 2022

Satellite telemetry (ST) has played a critical role in the management and conservation of polar bears ( Ursus maritimus ) over last 50 years. ST data provide biological information relevant to subpopulation delineation, movements, habitat use, maternal denning, health, human-bear interactions, accurate estimates vital rates abundance. Given that are distributed at low densities vast remote habitats, much provided by cannot be collected other means. Obtaining for requires chemical immobilization application tracking device. Although not been found have negative effects beyond several-day reduction activity, few decades opposition deployment satellite-linked radio collars resulted lack current many 19 recognized bear subpopulations. Here, we review uses evaluate its addressing 21 st century challenges, which include estimation sustainable harvest rates, understanding impacts climate warming, delineating habitat, assessing potential anthropogenic from tourism, resource development extraction. We subpopulations where consistently collected, was available estimate density, document sea-ice loss, inform related subsistence regulatory requirements. In contrast, some increased bias uncertainty ecological demographic parameters, range consequences. As loss due warming continues, there is greater need monitor distribution, abundance, connectivity. conclude continued collection will critically important benefits immobilizing small numbers individual order deploy devices significantly outweigh risks.

Language: Английский

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Are polar bear habitat resource selection functions developed from 1985–1995 data still useful?

Ecology and Evolution, Journal Year: 2019, Volume and Issue: 9(15), P. 8625 - 8638

Published: July 4, 2019

Greenhouse-gas-induced warming in the Arctic has caused declines sea ice extent and changed its composition, raising concerns by all circumpolar nations for polar bear conservation.Negative impacts have been observed three well-studied subpopulations. Most subpopulations, however, receive little or no direct monitoring, hence, resource selection functions (RSF) may provide a useful proxy of distributions. However, efficacy RSFs constructed from past data, that is, reference RSFs, be degraded under contemporary conditions, especially rapidly changing environment.We assessed published Arctic-wide using tracking data adult female bears captured Beaufort Sea. We compared telemetry-derived seasonal distributions to RSF-defined optimal habitat during period RSF model development, 1985-1995, two subsequent periods with diminished ice: 1996-2006 2007-2016. From these comparisons, we applicability conservation.In decades following 1985-1995 period, use availability declined melt, minimum, growth seasons. During maximum season (i.e., winter), used best available, which relatively across study. seasons, areas decreased was displaced north east Alaska Sea coast. As expanded their range occupied greater suboptimal habitat.Synthesis applications: due climate change continue challenge conservation. The distribution Southern remained similar season, so developed collected >20 years ago accurately winter distribution. In contrast, transitional minimum seasons showed predictive but were revealing increasingly forced habitats those

Language: Английский

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Identifying reliable indicators of fitness in polar bears

PLoS ONE, Journal Year: 2020, Volume and Issue: 15(8), P. e0237444 - e0237444

Published: Aug. 19, 2020

Animal structural body size and condition are often measured to evaluate individual health, identify responses environmental change food availability, relate availability effects on reproduction survival. A variety of metrics have been developed but relationships between these vital rates rarely validated. Identifying an optimal approach estimate the polar bears is needed improve monitoring their response decline in sea ice habitat. Therefore, we examined several commonly used indices (CI), mass, with female reproductive success cub survival among (Ursus maritimus) two subpopulations over three decades. To measurement application morphometrics CIs, also whether CIs independent age size–an important assumption for temporal trends—and factors affecting precision accuracy. Maternal mass fall prior denning were related production. Similarly, maternal length cubs or yearlings that accompanied her. However, not spring was production only probability These results suggest may be better indicators fitness than part because remove variation associated fitness. Further, exhibited variable growing lower longer despite being success. consistent findings from other species indicating a useful metric link conditions population dynamics.

Language: Английский

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An integrated population model for estimating the relative effects of natural and anthropogenic factors on a threatened population of steelhead trout

Journal of Applied Ecology, Journal Year: 2020, Volume and Issue: 58(1), P. 114 - 124

Published: Nov. 1, 2020

Abstract Assessing the degree to which at‐risk species are regulated by density‐dependent versus density‐independent factors is often complicated incomplete or biased information. If not addressed in an appropriate manner, errors data can affect estimates of population demographics, may obfuscate anticipated response a specific action. We developed Bayesian integrated model that accounts explicitly for interannual variability number reproducing adults and their age structure, harvest environmental conditions. apply 41 years threatened steelhead trout Oncorhynchus mykiss using freshwater flows, ocean indices releases hatchery‐born conspecifics as covariates. found compelling evidence under regulation, despite being well below its historical size. In portion lifecycle, we negative relationship between productivity (offspring per parent) peak winter positive with summer flows. also hatchery conspecifics. marine correlation North Pacific Gyre Oscillation. Synthesis applications . The combined substantial loss juvenile rearing habitat this river basin, suggests restoration could benefit steelhead. Our results imply programmes need be considered carefully respect availability recovery goals wild have indeed limited production potential steelhead, there likely significant trade‐offs providing opportunities via achieving goals. Furthermore, rates on fish been sufficiently low ensure very little risk overfishing.

Language: Английский

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Where do you think you’re going? Accounting for ontogenetic and climate‐induced movement in spatially stratified integrated population assessment models

Fish and Fisheries, Journal Year: 2020, Volume and Issue: 22(1), P. 141 - 160

Published: Sept. 19, 2020

Abstract Understanding spatial population structure and biocomplexity is critical for determining a species’ resilience to environmental anthropogenic perturbations. However, integrated models (IPMs) used develop management advice harvested populations have been slow incorporate dynamics. Therefore, limited research has devoted understanding the reliability of movement parameter estimation in models, especially spatially dynamic marine fish populations. We implemented simulation–estimation framework that emulated generic metapopulation explore impact ontogenetic climate‐induced distributional shifts between two The robustness stratified IPMs was explored across range parametrizations, including ignoring connectivity or estimating with various levels complexity. Ignoring detrimental accurate population‐specific biomass, while implementing intermediate complexity (e.g. two‐year two‐age blocks) performed best when no priori information about underlying available. One‐way mimicking poleward migrations presented greatest difficulties, but incorporation auxiliary on tag‐recapture data) reduced bias. continued development modelling approaches should allow resources be better utilized without increased risk. Additionally, expanded collection unique explicit data will enhance future.

Language: Английский

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