Assessing variation in social behaviors of group-living animals may provide insight into the impacts of population stressors. Using very high resolution (VHR) satellite imagery acquired over 3 years, we compared social group size and composition, as well as spatial and social cohesion in three beluga (Delphinapterus leucas) populations that experience different levels of harvest and vessel traffic exposure: Cumberland Sound, Eastern High Arctic-Baffin Bay, and Western Hudson Bay. We further explored the relationships between harvest, vessel activity, beluga density, and social context with beluga grouping characteristics to predict potential drivers of beluga social group dynamics. Mean group size decreased with harvest levels, possibly reflecting the effects of population decline or removal of key social individuals. Populations exposed to recent increases in vessel activity were associated with larger group sizes and greater spatial cohesion, possibly suggesting increased vigilance in response to vessel traffic. Adult-juvenile mixed groups were larger and had smaller inter-group distances than groups comprised of adults only, likely reflecting the dependence of younger whales on alloparental care. This study provides a novel application of VHR satellite imagery for beluga monitoring and highlights potential impacts of anthropogenic stressors on beluga populations.

Very high-resolution (VHR) satellite imagery has proven to be useful for detection of large to medium cetaceans, such as odontocetes and offers some significant advantages over traditional detection methods. However, the significant time investment needed to manually read satellite imagery is currently a limiting factor to use this method across large open ocean regions. The objective of this study is to develop a semi-automated detection method using object-based image analysis to identify beluga whales (Delphinapterus leucas) in open water (summer) ocean conditions in the Arctic using panchromatic WorldView-3 satellite imagery and compare the detection time between human read and algorithm detected imagery. The false negative rate, false positive rate, and automated count deviation were used to assess the accuracy and reliability of various algorithms for reading training and test imagery. The best algorithm, which used spectral mean and texture variance attributes, detected no false positives and the false negative rate was low (<4%). This algorithm was able to accurately and reliably identify all the whales detected by experienced readers in the ice-free panchromatic image. The autodetection algorithm does have difficulty separately identifying whales that are perpendicular to one another, whales below the surface, and may use multiple segments to define a whale. As a result, for determining counts of whales, a reader should manually review the automated results. However, object-based image analysis offers a viable solution for processing large amounts of satellite imagery for detecting medium-sized beluga whales while eliminating all areas of the imagery which are whale-free. This algorithm could be adapted for detecting other cetaceans in ice-free water.

The development of indicators as tools for ecosystem monitoring is a key step in the management of marine protected areas (MPAs). This study uses previously developed sex-specific body condition indices, blubber thickness, and girth, to assess temporal changes in body condition from 2000 to 2015 in harvested Eastern Beaufort Sea (EBS) beluga whales (Delphinapterus leucas). Specifically, the goals were to (1) examine seasonal and inter-annual trends of beluga body condition indicators over the harvest season; (2) evaluate associations of body condition indicators across sexes; and (3) test annual means of each body condition index for correlations to regional scale environmental drivers (i.e., the Pacific decadal oscillation (PDO) and sea-ice minimum (SIM) in the Beaufort Sea). Significant seasonal changes in male blubber thickness and female girth indices demonstrated the importance of short-term seasonal drivers. Whilst inter-annual changes in girth and blubber thickness indices revealed longerterm changes, that were correlated between males and females. Only the male girth index had significant relationships with environmental drivers: a negative relationship with the PDO at a zero-year lag, and a negative relationship with the SIM at a two-year lag. The PDO is believed to capture broader environmental changes occurring at wintering habitats and migration routes of the EBS beluga that reveals connectivity between the EBS beluga home range and body condition metrics. While body condition metrics for harvested EBS belugas are regularly collected under a long-running beluga monitoring program, the interpretation and application to MPA monitoring remains difficult. We recommend the continued collection of both girth and blubber thickness measurements along with the inclusion of Inuvialuit Knowledge and observations to strengthen interpretations and inform monitoring of beluga health.

Monitoring animal population abundance and distribution is essential for conservation and management. Recent advances in very high-resolution (VHR) satellite imagery allow for unprecedented detection and identification of animals, offering a potential alternative to conventional methods of population assessment such as aerial surveys. Here, we compare satellite and aerial survey images of a terrestrial walrus haul-out site in the Canadian High Arctic taken 1.5 hours apart. While the 30-cm resolution of the commercially available satellite image was insufficient to reliably count individual walruses visually, a manual digitization method successfully identified and delineated image areas confirmed visually to have walrus. Estimates of numbers of hauled out walrus obtained by multiplying the detected area by a range of densities in the aerial image (231) agreed well with actual counts in 35 and 55mm aerial images (217–240). Potential applications of this approach include quantitative abundance estimation or more simple monitoring of presence/absence over large expanses of remote areas that are logistically difficult to cover using survey aircraft.

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.

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.

Diel cycles in marine predator diving behaviour centre around the light-mediated diel vertical migration (DVM) of prey, and are considered critical for optimizing foraging and limiting competition across global seascapes. Yet, our understanding of predator diel behaviour is based primarily on examining relative depth usage between constant day/night cycles with no formal investigation of how varying light regimes interact with abiotic factors to shape diel activity. The extreme seasonal light regimes (midnight sun, polar night, day/night cycle) in the Arctic provide a unique natural experimental setting to empirically investigate the occurrence and intensity of diel behaviour in marine predators relative to changing light levels while concomitantly assessing interacting abiotic factors. Depth time series data from satellite-linked tags deployed on six beluga whales (Delphinapterus leucas) for up to 12 months were used to quantify diel behaviour by calculating dissimilarity in time-at-depth between periods of low and high solar altitude on each day. Generalized additive mixed effects models were used to examine the influence of hours of daylight across extreme light cycles, coupled with bathymetry and sea ice concentration; focal diel patterns were further examined relative to the thermal structure of the water column. As predicted, belugas exhibited cathemerality during the midnight sun, and initiated diel behaviour with the onset of the fall day/night cycle, with a marked increase in its intensity with the progression to equal day/night length. Occurrence of diel patterns, however, was complex; ceasing in regions with seafloor depths <700 m, and occurring with greatest intensity when the water column was thermally homogeneous within the upper 150 m. Through empirical investigation, this study demonstrates that the onset of day/night light cycles and presumably associated prey DVM can modulate predator diel dive behaviour under certain circumstances, but highlights how the complex interaction of abiotic factors with light regime shape dynamic spatiotemporal patterns. These findings, building on a body of recent work, emphasize that the traditional view of the ubiquitous occurrence of diel behaviour tied to DVM at the base of the food web oversimplifies vertical predator-prey interactions, identifying the need for more structured investigation. Read the free Plain Language Summary for this article on the Journal blog.

Dive behavior represents multiple ecological functions for marine mammals, but our understanding of dive characteristics is typically limited by the resolution or longevity of tagging studies. Knowledge on the time-depth structures of dives can provide insight into the behaviors represented by vertical movements; furthering our understanding of the ecological importance of habitats occupied, seasonal shifts in activity, and the energetic consequences of targeting prey at a given depth. Given our incomplete understanding of Eastern Beaufort Sea (EBS) beluga whale behavior over an annual cycle, we aimed to characterize dives made by belugas, with a focus on analyzing shifts in foraging strategies. Objectives were to (i) characterize and classify the range of beluga-specific dive types over an annual cycle, (ii) propose dive functions based on optimal foraging theory, physiology, and association with environmental variables, and (iii) identify whether belugas undergo seasonal shifts in the frequency of dives associated with variable foraging strategies. Satellite-linked time-depth-recorders (TDRs) were attached to 13 male belugas from the EBS population in 2018 and 2019, and depth data were collected in time series at a 75 s sampling interval. Tags collected data for between 13 and 357 days, including three tags which collected data across all months. A total of 90,211 dives were identified and characterized by twelve time and depth metrics and classified into eight dive types using a Gaussian mixed modeling and hierarchical clustering analysis approach. Dive structures identify various seasonal behaviors and indicate year-round foraging. Shallower and more frequent diving during winter in the Bering Sea indicate foraging may be energetically cheaper, but less rewarding than deeper diving during summer in the Beaufort Sea and Arctic Archipelago, which frequently exceeded the aerobic dive limit previously calculated for this population. Structure, frequency and association with environmental variables supports the use of other dives in recovery, transiting, and navigating through sea ice. The current study provides the first comprehensive description of the year-round dive structures of any beluga population, providing baseline information to allow improved characterization and to monitor how this population may respond to environmental change and increasing anthropogenic stressors.

During summer, the Eastern Beaufort Sea beluga whale ( Delphinapterus leucas (Pallas, 1776)) population aggregates in the waters of the Mackenzie Estuary and Tarium Niryutait Marine Protected Area (TNMPA). Guided by local communities’ priorities, this study aimed to better understand beluga summer habitat selection and to examine whether shifts in beluga distribution are expected under a changing climate. We used a resource selection function (RSF) based on aerial survey data and satellite remote sensing images to estimate the likelihood of beluga presence as a function of environmental conditions. The RSF revealed that belugas selected warm and turbid waters, with suspended particulate matter concentrations and sea surface temperatures ranging above average estuarine values. These specific conditions support hypotheses on the ecological roles of estuaries for belugas such as providing a thermal advantage for their calves or for beluga epidermal moulting. Using a diachronic analysis, we found a distribution shift towards coastal and inshore waters, areas already experiencing effects of climate change. Thus, the current distribution may reflect beluga responses to a changing climate, selecting warmer and more turbid areas. Our finding provides insight into current and evolving beluga habitat and habitat selection under a changing climate, which may help inform beluga management in the TNMPA.

Emergence of new technologies in remote sensing give scientists a new way to detect and monitor wildlife populations. In this study we assess the ability to detect and classify two emblematic Arctic cetaceans, the narwhal (Monodon monoceros) and beluga whale (Delphinapterus leucas), using very high-resolution (VHR) satellite imagery. We analyzed 12 VHR images acquired in August 2017 and 2019, collected by the WorldView-3 satellite, which has a maximum resolution of 0.31 m per pixel. The images covered Clearwater Fiord (138.8 km2), an area on eastern Baffin Island, Canada where belugas spend a large part of the summer, and Tremblay Sound (127.0 km2), a narrow water body located on the north shore of Baffin Island that is used by narwhals during the open water season. A total of 292 beluga whales and 109 narwhals were detected in the images. This study contributes to our understanding of Arctic cetacean distribution and highlights the capabilities of using satellite imagery to detect marine mammals.

With increased warming and open water due to climate change, the frequency and intensity of storm surges is expected to increase. Although studies have shown that strong storms can negatively impact Arctic ecosystems, the impact of storms on Arctic marine mammals is relatively unknown. In July 2016, an unusually large storm occurred in the Mackenzie Delta while instrumented seabed moorings equipped with hydrophones and oceanographic sensors were in place to study environmental drivers of beluga habitat use during their summer aggregation. The storm lasted up to 88 h, with maximum wind speeds reaching 60 km/h; historical wind data from Tuktoyaktuk revealed a storm of similar duration has not occurred in July in at least the past 28 years. This provided a unique opportunity to study the impacts of large storms on oceanographic conditions, beluga habitat use, and the traditional subsistence hunt that occurs annually in the delta. The storm resulted in increased water levels and localized flooding as well as a significant drop in water temperature (∼10 °C) and caused belugas to leave the area for 5 days. Although belugas returned after the storm ended, the subsistence hunt was halted resulting in the lowest beluga harvest between 1978 and 2017.

Understanding drivers of habitat use and selection of mobile species is critical for understanding the impacts of climate change and formulating management plans. Eastern Beaufort Sea beluga whales Delphinapterus leucas form large summering aggregations in the warm, fresh waters of the Mackenzie Estuary, Northwest Territories, Canada; however, the environmental factors driving spatial and temporal patterns of habitat use within the estuary are not fully understood. We used passive acoustic monitoring to record beluga presence during their summer aggregation (June-August) at known congregation areas and locations with unique oceanographic features in Kugmallit Bay in the Mackenzie River Estuary, while simultaneously recording environmental and oceanographic data. The effectiveness of hydrophones at determining beluga presence/absence was validated using shore-based observations. Multiple logistic regression was used to assess the influence of environmental conditions on presence/absence of belugas. Results indicate that temporal patterns of habitat use varied by location, and were influenced by environmental conditions such as temperature, salinity, and wind speed. Belugas did not frequent commonly used locations during periods with high-speed winds and moved farther into the estuary during periods of cold oceanic influxes. This study provides support for hypotheses that belugas use the location for moulting or to provide a thermal advantage for young belugas. This information can be used to inform decisions by northern communities and policy makers, thus aiding in management of the Beaufort Sea beluga population.

Monitoring marine protected areas requires simplifying complex marine ecosystems into a suite of indicators. The Tarium Niryutait Marine Protected Area (TN MPA), the first MPA in the Canadian Arctic is located in the Inuvialuit Settlement Region, NT and is selecting indicators for monitoring. Proposed health indicators for the TN MPA species of interest, the Eastern Beaufort Sea (EBS) beluga, include the body condition metrics blubber thickness and girth. Sex-specific body condition models for both metrics were developed to account for age, size, location, and timing of harvest from belugas harvested from 2000 to 2015. Models were tested to determine if the spatial variation is detected in the condition of belugas between the three areas of the TN MPA and between belugas harvested inside to outside of the TN MPA. Lastly, we assessed belugas from entrapment events to determine if indicator thresholds could be developed. Three of the indicators (girth male, girth female, blubber thickness male) contain both temporal and spatial factors, signalling the significant influence of year and harvest location on condition. Male belugas harvested from the western area of the TN MPA had smaller mean blubber thickness and girth compared to the other TN MPA areas, whereas there was no significant difference in female condition across the TN MPA. There was a significant difference inside and outside the TN MPA for all four indicators, with larger mean blubber thickness inside the TN MPA, females exhibiting larger mean girth and males exhibiting smaller mean girth inside the TN MPA. Indicators confirm that belugas from entrapment events had significantly lower body condition than belugas harvested during the summer and can serve as thresholds for condition indicators. This study provides guidance on the selection and use of condition indicators for their application in monitoring the TN MPA and demonstrates that careful consideration is required for indicator development and selection.

Aim 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 set of 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 continental 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 km(2)) in summer-autumn and 7% (83,202 km(2)) 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.

Two Arctic Marine Protected Areas (MPAs) (Tarium Niryutait and Anguniaqvia niqiqyuam) have been established in the Western Canadian Arctic, including the first in the Arctic, with conservation objectives directed to protect and maintain healthy beluga (Delphinapterus leucas) populations. The MPAs support the continued access of Inuvialuit (Western Arctic Inuit) to harvest beluga whales for food security and cultural purposes. The land claim and co-management framework for the Inuvialuit Settlement Region support the long term monitoring and management plans for this beluga population. We draw upon over 40 years of monitoring of the Eastern Beaufort Sea (EBS) beluga whale population and consider the utility of biological indicators for MPA management. In particular we focus on the conservation of a beluga population whose home range extends far beyond MPA boundaries (transboundary population with summer core area in excess of 36, 000 Km2). We conclude that the EBS beluga whales are effective indicators of environmental change, but that we have limited understanding of the temporal and spatial relationships between beluga responses to processes that drive environmental change. Management bodies are challenged with implementing indicators that measure the impacts of 'non-manageable' stressors such as climate change, and by uncertainty in the mechanistic relationships that drive biological indicators. Given that Inuvialuit continue to be astute observers of the environment and changing conditions, our assessment suggests that Indigenous knowledge will continue to enhance the development and interpretation of beluga whale indicators for use in MPA monitoring and management.

The eastern Beaufort Sea beluga whale Delphinapterus leucas population aggregates in the Mackenzie Estuary every summer, and moves toward the continental shelf and offshore waters in the late summer. From 2007 to 2009, systematic aerial surveys recorded beluga whale locations beyond the estuary, over the Mackenzie Shelf and offshore waters, where distributions were observed to occur widely. It is thought that beluga use of the offshore is primarily driven by feeding opportunities, and historical abundance trends suggest that the offshore may have become more attractive to beluga in response to prey availability. To determine drivers of beluga late summer habitat use, a resource selection function (RSF) model was used to measure se lection of 4 key environmental variables: (1) chlorophyll a, (2) sea surface temperature, (3) bathymetry and (4) distance from shore. Results revealed that all 4 variables contributed significantly to the individual 2007, 2008 and 2009 best-fit habitat models. Beluga preferred warmer sea surface temperatures (> 2 degrees C) and mid-to-high chlorophyll a concentrations (0.01-10 mg m(-3)), conditions that are indicative of enhanced local productivity and/or upwelling. Beluga distributions varied slightly between years, although high-use areas were identified in nearshore waters (0-50 m) offshore of the Tuktoyaktuk Peninsula, and along the continental shelf-slope (100-500 m), a region known to support a principal prey species, Arctic cod Boreogadus saida. This study improved knowledge of beluga habitat use in the offshore and revealed that selection of late summer oceanographic variables may provide support for foraging habitats, as these dynamic conditions are important to structuring forage fish ecosystems.

Climate change is expected to impact Arctic marine mammals, as they may be particularly vulnerable to large annual variability in the environment. Beluga whales ( Delphinapterus leucas ) occupy the circumpolar Arctic year-round, and seasonal movement patterns in this landscape are closely linked to sea ice and changing conditions. Here, we examine the association between beluga spring locations along the Mackenzie Shelf and three relevant habitat variables: sea ice (total concentration, floe size, and distance to ice edge), bathymetry and turbidity. Beluga locations in 2012 and 2013 were analyzed across the study area, as well as in three discrete subareas of the Mackenzie Shelf: Shallow Bay, Kugmallit Bay and Tuktoyaktuk Peninsula. In both years, beluga were found more than expected by chance in locations of open water/light ice concentrations and medium ice floes, and displayed a significant association with turbid water (i.e., increased freshwater flow). Largely ice-free conditions in 2012 led to a wide variation in habitat use in all three subareas. Beluga whales in 2012 preferred the ice edge and were found in heavier ice concentrations, larger floes and high turbidity water in the Shallow Bay subarea. Open water environments were preferred by beluga found in the Kugmallit Bay subarea. In contrast, heavy ice conditions in 2013 resulted in restricted habitat use and selection of shallow depth (<50 m) and low levels of turbidity. These results provide knowledge on spring habitat selection as well as insight into the adaptability of beluga under expected changes associated with climate and human activity in the Beaufort Sea.

Over the past decade or so, international research efforts, many of which were part of the International Polar Year, have accrued our understanding of the Arctic outflow shelves. The Arctic outflow shelves, namely the East Greenland Shelf (EGS) and the Canadian Arctic Archipelago (CAA), serve as conduits through which Arctic sea ice and waters and their properties are exported to the North Atlantic. These shelves play an important role in thermohaline circulation and global circulation patterns, while being influenced by basin-scale and regional changes taking place in the Arctic. Here, we synthesize the current knowledge on key forcings of primary production and ecosystem processes on the outflow shelves, as they influence their structure and functionalities and, consequently their role in Arctic Ocean productivity and global biogeochemical cycles. For the CAA, a fresh outlook on interannual and decadal physical and biological time-series reveals recent changes in productivity patterns, while an extensive analysis of sea ice conditions over the past 33 years (1980-2012) demonstrates significant declines in multi-year ice and a redistribution of ice types. For the EGS, our analysis shows that sea ice export strongly contributes to structuring spatially diverse productivity regimes. Despite the large heterogeneity in physical and biological processes within and between the outflow shelves, a conceptual model of productivity regimes is proposed, helping identify general productivity patterns and key forcings. The different productivity regimes are expected to respond differently to current and future Arctic change, providing a useful basis upon which to develop predictive scenarios of future productivity states. Current primary production estimates for both outflow shelves very likely underestimate their contribution to total Arctic production. Crown Copyright (C) 2015 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

ABSTRACTBased on the regions in the western Canadian Arctic as outlined by the Canadian Ice Service, the normals and trends from 1981 to 2010 were analysed for the monthly surface air temperature, monthly wind speed and direction. For the month of September, the temperatures from 1981 to 2010, for all of the defined regions, increased by 2–4 °C. The monthly concentrations of sea ice and multiyear ice were analysed for normals and trends from 1981 to 2010. Although the whole Arctic has seen a large reduction in the minimum sea ice extent, in the defined region of study during September, only the Beaufort Sea region shows a statistically significant decrease in sea ice concentrations. Correlations between the climatological state variables and sea ice were investigated in this study to determine relative thermodynamic and dynamic contributions to a decline in sea ice extent in the Western Arctic. As expected, the regions of interest all showed a statistically significant correlation between the surface air temperatures and the total sea ice concentrations. However, neither the wind speed nor the direction had a strong correlation on the sea ice concentration trends. This study showed that in the regions investigated, thermodynamic forcing of sea ice is the dominant driver when compared with dynamic forcing, which is a secondary driver in the western Canadian Arctic.