Our limited knowledge of the marine mammal fauna in northernmost Greenland and Canada, specifically north of 80°N, relies largely on opportunistic observations collected during expeditions with ...different objectives. The narwhal (Monodon monoceros) migrates long distances in response to ice formation and decay and is notoriously skittish, avoiding areas with ice breakers. Scattered observations from the past 20 years, assessed together with historical observations after 1881, suggest that there is a population of narwhals that uses Hall Basin and its adjacent fjord systems—for example, Nares Strait—as a summer ground. Dating the tusks and bones that have been found shows that narwhals were present in this area as far back as nearly 7000 years ago. The wintering locations of these narwhals remain unknown, highlighting the need to investigate whether they are vulnerable to hunting activities in north-west Greenland. By gaining a better understanding of the narwhals’ winter behaviour and potential hunting risks, we can develop more informed conservation and management strategies for this population.
Abstract
Background
Due to their Arctic habitat and elusive nature, little is known about the narwhal (
Monodon monoceros
) and its foraging behaviour. Understanding its ability to catch prey is ...essential for understanding its ecological role, but also to assess its ability to withstand climate changes and anthropogenic activities. Narwhals produce echolocation clicks and buzzing sounds as part of their foraging behaviour and these can be used as indicators of prey capture attempts. However, acoustic data are expensive to store on the tagging devices and require complicated post-processing. The main goal of this paper is to predict prey capture attempts directly from acceleration and depth data. The aim is to apply broadly used statistical models with interpretable parameters. The ultimate goal is to be able to estimate prey consumption without the more demanding acoustic data.
Results
We predict narwhal buzzing activity using mixed-effects logistic regression models with 83 features extracted from acceleration and depth data as explanatory variables. The features encompass both instantaneous values as well as delayed values to capture behavioural patterns lasting several seconds. The data correlations were not strong enough to predict the exact timing of the buzzes, but were reliably able to detect buzzes within a few seconds. Most of the of the buzz predictions were within 2 s of an observed buzz (68%), increasing to 94% within 30 s. Conversely, 46% of the observed buzzes were within 2 s of a predicted buzz, increasing to 82% within 30 s. Additionally, the model performed well, although with a tendency towards underestimation of the number of buzzes per dive. In total, we predicted 17, 557 buzzes versus 25, 543 observed across data from 10 narwhals. Classifying foraging and non-foraging dives yielded a precision of 86% and a recall of 91%.
Conclusion
We conclude that narwhal foraging estimation through acceleration and depth data is a valid alternative or supplement to buzz recordings, even when using somewhat simple statistical methods, such as logistic regression. The methods in this paper can be extended to foraging detection in similar marine species and can aid instrument development.
We assessed long-term changes in the feeding ecology and mercury (Hg) accumulation in Eastern High Arctic-Baffin Bay beluga (Delphinapterus leucas) using total Hg and stable isotope (δ13C, δ15N) ...assays in teeth samples from historical (1854–1905) and modern (1985–2000) populations. Mean δ13C values in teeth declined significantly over time, from −13.01 ± 0.55‰ historically to −14.41 ± 0.28‰ in 2000, while no consistent pattern was evident for δ15N due to high individual variability within each period. The temporal shift in isotopic niche is consistent with beluga feeding ecology changing in recent decades to a more pelagic and less isotopically diverse diet or an ecosystem wide change in isotope profiles. Mercury concentrations in modern beluga teeth were 3–5 times higher on average than those in historical beluga. These results are similar to the long-term trends of Hg and feeding ecology reported in other beluga populations and in other Arctic marine predators. Similar feeding ecology shifts across regions and species indicate a consistent increased pelagic diet response to climate change as the Arctic Ocean progressively warmed and lost sea ice. Previously, significant temporal Hg increase in beluga and other Arctic animals was attributed solely to direct inputs of anthropogenic Hg from long-range sources. Recent advances in understanding the Arctic marine Hg cycle suggest an additional, complementary possibilityincreased inputs of terrestrial Hg of mixed anthropogenic-natural origin, mobilized from permafrost and other Arctic soils by climate warming. At present, it is not possible to assign relative importance to the two processes in explaining the rise of Hg concentrations in modern Arctic marine predators.
There is an increasing need for comprehensive oceanographic sampling, and taking advantage of marine mammal studies of movements and habitat use for augmenting spatial and temporal coverage, ...especially in remote and inaccessible areas, is an attractive approach. Oceanographic sampling instruments that transmit profiles of temperature and salinity (CTD) via satellite were deployed on bowhead whales Balaena mysticetus. A novel satellite-linked CTD tag (WC) was compared to an established design (SMRU). The two types of tags were deployed equally on nine bowhead whales in West Greenland. Both tag types used Argos for relaying data and locations, while the WC tag also provided Fastloc-GPS for more accurate locations. One whale carried both tag types. When comparing the two tag types deployed on the same whale, more complete data were obtained from the WC tag in terms of number of profiles, locations and transmissions received, although placement of the tag on the back of the whale and antenna position may have affected some of these parameters. Why transmissions terminated is difficult to determine, however, physical loss of the tag from the whale and mechanical damage to the antenna are the most likely; none of the tags failed because of battery exhaustion. Although, differences in performance of the two tag types were found, we conclude that both satellite-linked CTD tag types deployed on large cetaceans can provide high resolution oceanographic profiles at times and in areas where traditional methods for collecting oceanographic data are logistically difficult and prohibitively expensive.
•Bowhead whales in west Greenland as real-time autonomous sampling platforms.•Salinity, temperature, depths and position sampled by two CTD satellite tags types.•The tags provided data for up to 155 days.•When placed on the same whale, performance was generally better for one tag type.•An ecological understanding help to learn how bowhead whales respond to rising temp.
Spitsbergen's bowhead whales (
Balaena mysticetus
) were hunted to near extinction in the world's first commercial whaling enterprise; this population clearly remains threatened, but nothing is known ...about its distribution, making assessment unfeasible. In this study, we document range, movement patterns and habitat preferences of this population, based on tagging done from an icebreaker-based helicopter. Despite their reduced abundance, Spitsbergen's bowhead whales occupy much of their historical range, stretching across the northern Barents Region from East Greenland eastward to Franz Josef Land. Unlike larger bowhead populations to the west, they do not migrate in a classical sense, but rather disperse from wintering grounds in the northernmost parts of their range during spring, returning northward again in autumn, a pattern opposite in terms of directionality compared to other Arctic bowhead whale populations. The extreme affiliation of this population with cold, ice-filled waters is a concern given ongoing climate warming and concomitant rapid sea ice habitat loss.
Individuals of different sex or age can vary in their prey and habitat resource use due to differences in behaviour, life history, energetic need, or size. Harbour porpoises are small cetaceans that ...need to feed constantly to meet their high metabolic demands. In West Greenland, the species has a unique offshore, deep-water ecology. Here, we use bone collagen carbon (
δ
13
C) and nitrogen (
δ
15
N) isotope compositions to elucidate sex and size differences in the foraging ecology of harbour porpoises from this region. Female harbour porpoises are larger than males; we find females have a higher trophic level, and
δ
15
N significantly positively correlates with size for females. This indicates that size may matter in the ability of females to handle larger prey and/or dive deeper to catch higher trophic level prey. The results suggest that females, which also nurse their calves, may be under different ecological constraints than males. We also analysed the harbour porpoise data with available stable isotope data from Greenland populations of belugas and narwhals. We find that harbour porpoises have a lower trophic level than the other species, which is consistent with their smaller body size, and their diet consisting primarily of capelin. Furthermore, harbour porpoises have the largest ecological niche of the three species, in accordance with tagging studies indicating they have a wider range than belugas and narwhals and occur in shelf and deep offshore waters of the sub-arctic and North Atlantic.
Insight into animal movements is essential for understanding habitat use by individuals as well as population processes and species life-history strategies. In this study, we instrumented 25 fin ...whales with ARGOS satellite-transmitters in Svalbard, Norway, to study their movement patterns and behaviour (Area Restricted Search (ARS), transiting or unknown) during boreal autumn/early winter. Ten of the whales stayed in the tagging area (most northerly location: 81.68°N) for their entire tracking periods (max 45 days). The other 15 whales moved in a south-westerly direction; the longest track ended off the coast of northern Africa (> 5000 km from the tagging location) after 96 days. The whales engaged in ARS behaviour intermittently throughout their southward migrations. During transit phases the whales moved quickly; one individual maintained an average horizontal speed of 9.3 km/h (travelling 223 km per day) for a period of a week. This study documents that: (1) some fin whales might remain at high latitudes during winter; (2) the whales that do migrate probably feed along the way; (3) they can maintain high transiting speed for long periods and; (4) one breeding area for this species is likely located in deep, warm water some 100 km west of Morocco.
Abstract
Full mitochondrial genomes were assembled for 12 recently sampled animals from the Svalbard bowhead whale (Balaena mysticetus) stock via high-throughput sequencing data, facilitating ...analysis of the demographic history of the population for the first time. The Svalbard population has retained noticeable amounts of mitochondrial genome diversity despite extreme historical harvest levels. Haplotype and nucleotide diversities were similar to those estimated earlier for other bowhead whale populations. The reconstructed demographic history was in accordance with a boom–bust scenario, combining a slight Pleistocene population growth 25 000–35 000 years ago and a Holocene decline. Employing a mutation rate of 3.418 × 10–8 substitutions per site per year, the time to the most recent common ancestor for the mitochondrial genomes of the contemporary Svalbard bowhead whales was estimated to be 68 782 (54 353–83 216) years before the present. Based on 370 bp fragments of the D-loop region, significant genetic differentiation was detected between all extant bowhead whale populations across the circumpolar Arctic. Thus, the Svalbard bowhead whales can be regarded as a population with its own genetic legacy.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Understanding the energy requirement and prey consumption of Arctic predators is crucial to assess their vulnerability to climate change. The bowhead whale (
Balaena mysticetus
) is the largest ...predator of the Arctic, with Disko Bay in Greenland constituting a major feeding ground for a segment (predominantly larger juveniles and adult non-lactating females) of the Eastern Canada-West Greenland population. We used unmanned aerial vehicle photogrammetry to measure the body size and condition of bowhead whales in Disko Bay during the spring (March 26–June 1, 2022), from which we quantified their energy requirements and prey consumption. Measurements of body length, width and height were used to estimate the body volume and condition of juveniles (50 measurements from 39 individuals) and adults (232 measurements from 154 individuals). The body condition of adults increased at a rate of 0.112 percentage points day
−1
, or 44.1–87.8 L of blubber day
−1
(for lengths 13.0–17.0 m). Using published data from harvested whales, the estimated blubber mass gain was 37.1–73.9 kg day
−1
, which equals an energy deposition rate of 1.01–2.01 GJ day
−1
. Body maintenance costs were predicted from allometric models, while activity costs and the heat increment of feeding were derived from published archival tag data. Reported length-at-age curves were used to estimate somatic growth costs. The energy requirements for juveniles and adults were 0.621–0.778 GJ day
−1
(for lengths 11.0–12.9 m) and 3.662–7.826 GJ day
−1
(for lengths 13.0–17.0 m), respectively, which equals a prey consumption rate of 17–22 kg of prey day
−1
(0.1% of body mass) and 102–218 kg day
−1
(0.3% of body mass).
The warmest water reaching the east and west coast of Greenland is found between 200 and 600 m. While important for melting Greenland's outlet glaciers, limited winter observations of this layer ...prohibit determination of its seasonality. To address this, temperature data from Argo profiling floats, a range of sources within the World Ocean Database, and unprecedented coverage from marine‐mammal borne sensors have been analyzed for the period 2002–2011. A significant seasonal range in temperature (~1‐2°C) is found in the warm layer, in contrast to most of the surrounding ocean. The phase of the seasonal cycle exhibits considerable spatial variability, with the warmest water found near the eastern and southwestern shelf break toward the end of the calendar year. High‐resolution ocean model trajectory analysis suggests the timing of the arrival of the year's warmest water is a function of advection time from the subduction site in the Irminger Basin.
Key Points
Seasonal temperature cycle found in the subsurface warm layer around GreenlandThere is a distinctive spatial variability to the phase of the seasonal cyclePhase of seasonal cycle related to water's travel time from the Irminger Sea
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