Long-term Trends in the Population Ecology of Polar Bears in Western Hudson Bay in Relation to Climatic Change

From 1981 through 1998, the condition of adult male and female polar bears has declined significantly in western Hudson Bay, as have natality and the proportion of yearling cubs caught during the open water period that were independent at the time of capture. Over this same period, the breakup of the sea ice on western Hudson Bay has been occurring earlier. There was a significant positive relationship between the time of breakup and the condition of adult females (i.e., the earlier the breakup, the poorer the condition of the bears). The trend toward earlier breakup was also correlated with rising spring air temperatures over the study area from 1950 to 1990. We suggest that the proximate cause of the decline in physical and reproductive parameters of polar bears in western Hudson Bay over the last 19 years has been a trend toward earlier breakup, which has caused the bears to come ashore in progressively poorer condition. The ultimate factor responsible for the earlier breakup in western Hudson Bay appears to be a long-term warming trend in April-June atmospheric temperatures.De 1981 à la fin de 1998, la condition physique de l'ours polaire adulte, mâle et femelle, s'est détériorée de façon importante dans l'ouest de la baie d'Hudson, tout comme le nombre de naissances et la proportion d'oursons de l'année pris durant la période d'eau libre, et qui étaient indépendants au moment de leur capture. Au cours de la même période, la débâcle de la banquise sur l'ouest de la baie d'Hudson s'est produite plus tôt. Il existait un lien très marqué entre le moment de la débâcle et la condition physique des femelles adultes (c.-à-d. que plus la débâcle se produisait tôt, plus les ourses étaient en mauvaise condition physique). La tendance à une débâcle précoce était également corrélée à l'augmentation de la température ambiante printanière dans la zone d'étude de 1950 à 1990. On suggère que la cause immédiate du déclin des paramètres physiques et reproducteurs de l'ours polaire dans l'ouest de la baie d'Hudson au cours des derniers 19 ans a été une tendance à une débâcle précoce, ce qui amené les ours à venir sur la terre ferme dans un état de plus en plus mauvais. Le facteur responsable de la débâcle précoce dans la baie d'Hudson semble être en fin de compte la tendance au réchauffement à long terme de l'atmosphère en avril et en juin

Polar Bear Distribution and Abundance on the Southwestern Hudson Bay Coast During Open Water Season, in Relation to Population Trends and Annual Ice Patterns

In Hudson Bay, all the ice melts in summer, and the last areas to be ice-free (around mid-to-late July) are usually off the coasts of Manitoba and Ontario. Thus, all polar bears are forced ashore to fast until freeze-up in November (ca. four months). Pregnant females remain ashore for eight months. In most years from 1963 through 1997, aerial surveys to monitor polar bear populations were conducted along all or part of the coastline between Cape Churchill, Manitoba, and Cape Henrietta Maria, Ontario, in late August and early September. Satellite data, from which breakup and ice absence times could be estimated, first became available in 1971. The numbers of animals counted were tallied in two subareas within Manitoba and three within Ontario. We evaluated the coastal counts, along with independent data on the movements of tagged bears and annual patterns of ice breakup from 1971 through 1996. We concluded that 1) the coastal survey data reliably indicated the population trends in Manitoba and Ontario; 2) little exchange occurred between the Western Hudson Bay (Manitoba) and Southern Hudson Bay (Ontario) populations; 3) between 1971 and 2001, there was a statistically significant trend toward earlier breakup of sea ice off the Manitoba coast, but not off the Ontario coast; 4) the onset of ice absence along the coast had no significant relationship to the number of bears present in each sub-sampling area within either the Manitoba or the Ontario population, but did significantly influence the distribution of bears on the coastline of each province independently of the other; 5) timing of the surveys can influence the results; and 6) adult male and female bears both showed a high degree of fidelity to specific areas during summer, independent of the pattern of ice breakup.Dans la baie d'Hudson, toute la glace fond en été, et les dernières zones à être non englacées (du milieu à la fin de juillet environ) se trouvent généralement au large des côtes du Manitoba et de l'Ontario. Ainsi, tous les ours polaires sont forcés de rester sur la terre ferme et de jeûner jusqu'à l'engel en novembre (soit environ quatre mois). Les femelles gravides, elles, restent sur la terre ferme pendant huit mois. Presque chaque année entre 1963 et 1997, à la fin août et au début de septembre, on a effectué des relevés aériens pour surveiller les populations d'ours polaires le long du littoral entre Cape Churchill, au Manitoba, et Cape Henrietta-Maria, en Ontario. Les données satellitaires, qui ont permis d'estimer la période de la débâcle et celle de l'absence de glace, sont devenues disponibles à partir de 1971. Le nombre d'animaux repérés a été inventorié comme provenant de deux sous-zones à l'intérieur du Manitoba et de trois à l'intérieur de l'Ontario. On a évalué le dénombrement des relevés côtiers ainsi que des données indépendantes sur les déplacements d'ours marqués et les schémas annuels de débâcle de 1971 à la fin de 1996. On en a conclu que: 1) les données des relevés côtiers révélaient de façon fiable les tendances démographiques au Manitoba et en Ontario; 2) il n'y avait que peu d'échanges entre les populations de la baie d'Hudson occidentale (Manitoba) et de la baie d'Hudson méridionale (Ontario); 3) entre 1971 et 2001, il y a eu une tendance statistiquement significative à une débâcle précoce au large du littoral manitobain, mais pas au large du littoral ontarien; 4) le début de l'absence de glace le long de la côte n'avait pas de lien marqué avec le nombre d'ours présents dans chaque secteur de sous-échantillonnage, au sein de la population du Manitoba ou de celle de l'Ontario, mais cette absence de glace avait une forte incidence sur la distribution des ours le long de la côte de chaque province indépendamment l'une de l'autre; 5) le choix de l'époque des relevés peut influencer les résultats; et 6), durant l'été, les ours mâles comme femelles manifestaient une grande fidélité pour des secteurs spécifiques, indépendamment de l'évolution de la débâcle

Belugas in the Mackenzie River estuary, NT, Canada: Habitat use and hot spots in the Tarium Niryutait Marine Protected Area

AbstractThe Tarium Niryutait MPA (TNMPA) was created in 2010, through the collaborative efforts of Fisheries and Oceans Canada, the Inuvialuit, private industry and local stakeholders. The purpose of the TNMPA is to conserve and protect the biological resources within the Mackenzie Estuary, ensuring viability of a healthy population of beluga whales. TNMPA regulations allow for the conduct of certain industry activities (e.g., dredging, transportation, and hydrocarbon exploration and production activity), as long as disturbance, damage, destruction or removal of belugas do not occur or are not expected. Our goal is to summarize baseline knowledge of the times, areas and patterns of aggregation of belugas in the TNMPA, to inform future monitoring, research and environmental assessments of any developments proposed for the TNMPA. Sightings of surfaced belugas in the Mackenzie River estuary made during seven summers of aerial surveys between 1977 and 1992 were examined using contemporary geospatial analytical methods. A total of 77 aerial surveys met the minimum criteria for inclusion: flown in their entirety, without interruption, under calm sea conditions, and with full visibility. The distribution of surfaced belugas was significantly clustered in three time periods (June 26–July 9, July 10–20, July 21–31) and in all sub areas of the TNMPA (Ripley's L, p < 0.0001). Sighting rates varied by subarea and time period, with Niaqunnaq Bay having rates 3–4 times higher (p < 0.0001) in the corresponding period, compared with West Mackenzie (WM), East Mackenzie (EM) and Kugmallit (KB) bays, in all but WM in late July. During early and mid-July of 1977–1985, belugas were aggregated in seven localized, recurrent geographic areas within the TNMPA, termed here as ‘hot spots’. Results will foster more confident and informed decisions about the acceptability of proposed industry activities in the TNMPA, ensuring assessments are evidence-based and not unnecessary restrictive

Development of a small-scale approach to assess sea ice change using weekly ice charts, with application to Anguniaqvia Niqiqyuam Marine Protected Area

Broad-scale changes in sea ice have been documented across the Arctic; however, less is known about sea ice decline at smaller scales, focused at high-priority areas such as marine protected areas (MPAs) or places identified as important by Indigenous Peoples. Here, we develop a small-scale application of assessing sea ice change using weekly sea ice charts and apply that to assess sea ice change in Anguniaqvia Niqiqyuam MPA (ANMPA) from 1980 to 2019. Over that 40-year period, sea ice coverage in ANMPA decreased and open water increased by approximately a month (31.6 days at 50% ice; 33.8 days at 20% ice remaining during break-up and 80% ice formed during freeze-up). Break-up has gone from occurring in mid- or late July to occurring in late June or early July. Freeze-up has changed from occurring in mid-October to occurring in early November. As sea ice decline may have dramatic impacts for the ecosystem and consequences for the people that rely on this important area, we highlight the need to better understand the impacts of sea ice decline in small-scale priority places and also contribute to the development of community-scale approaches to increase the accessibility of assessing change

Summer distribution and habitat preference of beluga whale social groups in the Eastern Beaufort Sea

In social animals, group composition can cause variations in individual needs that can influence responses to habitat trade-offs, such as predator exposure or foraging opportunities. The Eastern Beaufort Sea beluga whales (Delphinapterus leucas (Pallas, 1776)) form different group types and cover multiple habitat types in summer. This study compares the habitat preference of three beluga social group types: (1) individual belugas, (2) groups of adults, and (3) groups with at least one calf. Observations were collected during aerial surveys in July and August 2019. For each month, beluga distribution was analyzed with hierarchical generalized additive models, as a function of group type and four covariates: sea surface temperature, bathymetry, slope, and distance to the coastline. Group type, water temperature, and bathymetric features best explained beluga distribution. In July, groups of adults preferred the continental shelf, whereas individual belugas and groups with calves preferred the continental slope. In August, groups of adults and groups with calves were found in Amundsen Gulf at similar depths. For both months, individual belugas associated more with deeper and colder areas. The preferences often corresponded to previously published distributions of the beluga's main prey species, suggesting that foraging opportunities and size-related energy requirements strongly influence habitat use

Abundance and species diversity hotspots of tracked marine predators across the North American Arctic

International audienceAim: Climate change is altering marine ecosystems worldwide and is most pronounced in the Arctic. Economic development is increasing leading to more disturbances and pressures on Arctic wildlife. Identifying areas that support higher levels of predator abundance and biodiversity is important for the implementation of targeted conservation measures across the Arctic.Location: Primarily Canadian Arctic marine waters but also parts of the United States, Greenland and Russia.Methods: We compiled the largest data setof existing telemetry data for marine predators in the North American Arctic consisting of 1,283 individuals from 21 species. Data were arranged into four species groups: (a) cetaceans and pinnipeds, (b) polar bears Ursus maritimus (c) seabirds, and (d) fishes to address the following objectives: (a) to identify abundance hotspots for each species group in the summer–autumn and winter–spring; (b) to identify species diversity hotspots across all species groups and extent of overlap with exclusive economic zones; and (c) to perform a gap analysis that assesses amount of overlap between species diversity hotspots with existing protected areas.Results: Abundance and species diversity hotpots during summer–autumn and winter–spring were identified in Baffin Bay, Davis Strait, Hudson Bay, Hudson Strait, Amundsen Gulf, and the Beaufort, Chukchi and Bering seas both within and across species groups. Abundance and species diversity hotpots occurred within the conti -nental slope in summer–autumn and offshore in areas of moving pack ice in winter–spring. Gap analysis revealed that the current level of conservation protection that overlaps species diversity hotspots is low covering only 5% (77,498 km2) in summer–autumn and 7% (83,202 km2) in winter–spring.Main conclusions: We identified several areas of potential importance for Arctic marine predators that could provide policymakers with a starting point for conservation measures given the multitude of threats facing the Arctic. These results are relevant to multilevel and multinational governance to protect this vulnerable ecosystem in our rapidly changing world