Harp Seals Research Articles

Space use of polar bears (<i>Ursus maritimus</i>) in Davis Strait in relation to sea ice and harp seals (<i>Pagophilus groenlandicus</i>)

Polar bears (<i>Ursus maritimus</i>) rely on seals as their primary prey, yet predator-prey spatial relationships are poorly understood. We examined the spatial relationship between Davis Strait polar bears and harp seals (<i>Pagophilus groenlandicus</i>), using satellite-telemetry for both species. We analyzed sea ice trends using remote sensing (1979-2021) to examine how their environment may be changing using four sea ice seasons (freeze-up, winter, break-up, and summer). Sea ice cover decreased and summer season lengthened over time. Polar bears (n=23) tracked in 1991-2001 for 7-12 months had a mean 95% minimum convex polygon home range size (MCP) of 102,864 km<sup>2</sup> (SE=15,236 km<sup>2</sup>) and a mean 95% kernel density home range size (KDE) of 66,215 km<sup>2</sup> (SE=59,688 km<sup>2</sup>). Harp seals (n=29) tracked for 5-8 months in 1993-2005 had a mean 95% MCP of 464,330 km<sup>2</sup> (SE=47,009 km<sup>2</sup>) and a mean 95% KDE of 256,016 km<sup>2</sup> (SE=31,566 km<sup>2</sup>). During freeze-up, the core-use areas of both species did not overlap, but the broad-use areas did. During break-up, the broad-use areas overlapped more than the core-use areas. The space use of both species was influenced by the sea ice seasons and these seasons have changed over time.

The diet and diving behaviour of the ringed seal (Pusa hispida) in Kangia (Ilulissat Icefjord), Greenland

AbstractThis study uses telemetry and stomach content analysis to describe the ringed seals’ dive pattern and prey selection within Kangia (Ilulissat Icefjord), Greenland, where the ringed seals are known to be exceptionally large and genetically distinct. Data from twenty-four ringed seals (Pusa hispida) tagged in Kangia, with satellite relay data loggers from 2012 to 2020, were used to describe the dive patterns. The transmitters were active between 28 and 270 days and showed that subadults most frequently dove to around 150 m. Adult males frequently dove to this depth, but they also had a second frequently visited depth at around 400 m, some adults significantly deeper. Adult males generally dove deeper than females and adult seals showed deeper dives during the winter, a feature that was less prominent in subadults. The stomach content from ringed seals (n = 108) harvested in Kangia by subsistence hunters revealed that polar cod (Boreogadus saida), capelin (Mallotus villosus), mysids (Mysis oculata, M. littoralis, M. Polaris) and shrimps (mainly Pandalus borealis) were the dominant prey. Shrimps were observed more often in adults, likely due to the frequently visited dive depth of around 400 m, whereas mysids were more observed in small subadult seals. The stomach content from harp seals (Pagophilus groenlandicus) and Greenland halibut (Reinhardtius hippoglossoides) caught in Kangia also showed a strong niche overlap with the ringed seals. These findings outline the unique ecological adaptations and the importance of Kangia as a critical habitat of ringed seals.

Marine Hunting of Pinnipeds (Pinnipedia) on the Coats of the White Sea in the Eneolithic

This is a study of initial stages of adaptation of the ancient human population to the use of aquatic food supplies in the White Sea. The main aim of archaeozoological analysis was to study the processes of formation of faunal remains and strategies on seals hunting during the Eneolithic in the White Sea region. The archaeological source material consists of faunal remains recovered from two Eneolithic sites of the Kandalaksha bay. The results of archaeozoological studies confirmed the high importance of the ringed seal and harp seal in the hunting prey of the inhabitants of the studied sites. Eneolithic hunting strategies of the White Sea region were closely related to the behavioral and ecological patterns of seals. The seal hunt was based on a model of exploiting a massive seasonal resource. Hunting pressure on the ringed seal and harp seal populations was significant. Seals were the main suppliers of meat, skin and fat for the inhabitants of the Eneolithic sites of this part of Fennoscandia. The studies of the lithic tools from the Early Metal period settlements from Kandalaksha bay provide additional evidences of a specialized marine hunting. Apparently, in the Eneolithic (IV – III millennia calBC), the economic and cultural type of sea hunters was formed on the shores of the White Sea.

Multispecies Discrimination of Seals (Pinnipeds) using Hidden Markov Models (HMMs)

Hidden Markov Models (HMMs) were developed and implemented for the discrimination of 5 available Seals (Pinnipeds), namely the Bearded Seal (Erignathus barbatus), Harp Seal (Pagophilus groenlandicus), Leopard Seal (Hydrurga leptonyx), Ross Seal (Ommatophoca rossii), and Weddell Seal (Leptonychotes weddellii). The main objectives of the experiments were to study the impact of the frame size and step size and number of states for feature extraction and acoustic models on classification accuracy. Based on the experiments using Mel-Frequency Cepstral Coefficients (MFCCs) extracted from the vocalizations (15 ms frame size and 4 ms step size), HMMs containing 20 states with single underlying Gaussian Mixture Model (GMM) produced discrimination of 95.77%. From the results, the framework could be applied to analysis for other marine mammals for both classification and detection of vocalizations and species.

Space‐use strategies drive diet composition of Baffin Bay polar bears

AbstractPolar bears (Ursus maritimus) depend on sea ice to hunt their ice‐associated prey. However, climate‐induced sea ice loss is leading to changes in space‐use strategies of polar bears, with bears in some subpopulations spending more time on land or selecting alternative habitats. One such documented alternative habitat is glacier ice, which provides year‐round access to prey, although the feeding habits of polar bears using glacier ice relative to those following the retreating ice and/or seasonally moving onshore are not known. Here, we use adipose tissue from polar bears (n = 104) from the Baffin Bay subpopulation live‐captured in Northwest Greenland during the springs of 2009–2013 to investigate dietary patterns between space‐use strategies inferred from satellite telemetry data, while considering demographic and interannual variation. Using quantitative fatty acid signature analysis (QFASA) to generate diet estimates, ringed seals (Pusa hispida) and bearded seals (Erignathus barbatus) were estimated as the primary and secondary prey of Baffin Bay polar bears for all sex/age classes and sampling years, apart from a single anomalous year (2009) with a relatively high proportion of beluga (Delphinapterus leucas) and narwhal (Monodon monoceros). While demographic and short‐term temporal variation was minimal, fatty acid signatures and QFASA‐generated diet estimates clearly differed between polar bears using coastal and offshore space‐use strategies. “Offshore” adult females (n = 31), which make long‐distance movements across the Baffin Bay pack ice, had high proportions of C22‐chain length monosaturated fatty acids and diet estimates that included beluga, narwhal, harp (Pagophilus groenlandicus), and hooded seal (Cystophora cristata). “Coastal” adult females (n = 6), which remain resident at glacier fronts in Northwest Greenland year‐round including during the sea ice‐free season, consumed proportionally more ringed seals (+13%) and similar proportions of bearded seal, but essentially no beluga and narwhal or harp and hooded seal. Thus, space‐use strategy is a driver of intrapopulation diet variability. As space‐use strategies change with ongoing loss of sea ice habitat, our results suggest important ramifications for polar bear feeding patterns.

Advances and prerequisites for strontium isotope analyses through laser ablation in an aquatic context – Targeting Mid-Neolithic Baltic Sea harp seal (Pagophilus groenlandicus) mobility and breeding grounds

Harp seals (Phoca groenlandicus), once present in the Baltic Sea, now stand extinct. During the Middle Neolithic period, they held significant dietary importance for the Pitted Ware Culture hunter-fisher-gatherers in Scandinavia. Because they are no longer available for ecological studies, little is known about their specific behavioural intricacies, such as diet, mobility, and reproductive strategies. Because of the seal's pivotal role in these human societies and because they provide an interesting ecological case study on post-isolation ecological adaptation to new environmental conditions, a comprehensive investigation into Baltic Sea harp seal behaviour is warranted.In this pursuit, we employ sequential analysis of strontium isotope ratios (87Sr/86Sr) in harp seal teeth sourced from archaeological contexts across three study regions. This data is harmonized with osteometric analyses from fifteen archaeological sites from the Baltic Sea area, establishing a methodological framework for comprehending the Sr isotopic pathway in a brackish water inland sea. By adopting this approach, we unveil breeding and mobility patterns of the long-extinct Baltic Sea harp seals, approximate specific breeding areas connected to each group of seals and delve into the ontogenic temporal frame governing these observed patterns. This endeavour culminates in an enriched understanding of the adaptive behaviours exhibited by Baltic Sea harp seals and equips us with the insights necessary to decipher the lifestyle of the human societies intricately intertwined with them.

Assessment of mercury concentrations in fur, liver, and brain tissue from necropsied southern sea otters (Enhydra lutris nereis)

AbstractSouthern sea otters (Enhydra lutris nereis) are a federally listed threatened keystone species of the California kelp forest ecosystem and a sentinel species, indicating environmental health. Mercury (Hg) is a bioaccumulative neurotoxin that poses a threat to high trophic‐level species such as marine mammals. We quantified total Hg (THg) concentrations in fur, brain, and liver tissues of necropsied southern sea otters (n = 44) that stranded along the California coast from 2010 to 2019. THg concentrations differed significantly between fur and brain, and between liver and brain. Tissue type explained 64%, and sex explained only 3.3% of overall THg variability (0.48–46.1 μg/g dry weight). All individuals had liver Hg concentrations measuring well under the proposed lower‐limit low risk guideline for harp seals, Pagophilus groenlandicus. However, six sea otters exceeded the liver THg moderate risk threshold for terrestrial furbearers to which sea otters are closely related. These data represent baseline THg concentrations in fur, brain, and liver of the southern sea otter and build upon previous studies in various sea otter subspecies. Research on sea otter Hg tolerance and continued monitoring are needed to clarify potential health risks associated with the tissue concentrations observed in this study.

Microarchitecture of the penis bone (baculum) of a seal: A 3D morphometric examination using synchrotron and laboratory micro-computed tomography.

We examined the ultrastructure of the mammalian os penis at the high-resolution synchrotron level. Previously, bacular microanatomy had only been investigated histologically. We studied the baculum of the harp seal (Pagophilus groenlandicus), in which the baculum varies more in size and shape than does a mechanically constrained bone (humerus). We (1) investigated the microarchitecture of bacula and humeri from the same seal specimens, and (2) described changes in bone micro- and macro-morphology associated with age (n = 15, age range = 1-35 years) and bone type. We analyzed cross-sectional geometry non-destructively through laboratory micro-computed tomography. We suggest that the midshaft may resist axial compression while the proximal region may resist torsion, based on measurements of cross-sectional and cortical areas, perimeter, ratio of maximum and minimum moments of inertia, and polar moment of inertia. In addition, midshaft bacula may be less mechanosensitive than humeri, based on microstructural variables (e.g., volume, surface area, diameter associated with lacunae and cortical porosity) analyzed across age groupings. Our findings related to the microarchitecture of the pinniped baculum provide a basis for further studies on development, mechanical properties, functions, and adaptations in this and other pinniped species. Our use of a multi-modal imaging approach was minimally destructive for reproducible and accurate comparison of three-dimensional bone ultrastructure. Such methods, coupled with multidisciplinary analyses, enable diverse studies of bone biology, life history, and evolution using museum collections.

Oil Identification of harp seal and other select marine mammals

Because of the rich omega-3 fatty acids content, harp seal (Pagophilus groenlandicus) oil is a popular supplement that is packaged as pills in Canada and sold for medicinal purposes, although this practice is banned in the United States. Due to US regulations, it is important to be able to distinguish between fish oil and seal oil, but the taxonomic determination of oils provenance has been a difficult problem to solve. In this study, Direct Analysis in Real Time time-of-flight mass spectrometry (DART TOFMS) was used to analyze the chemotypes of blubber samples collected from seven species of marine mammals, including seals, sea lions, and a porpoise. Results indicated that the chemotype profiles found in negative-ion mode could be used to separate all of the species using Discriminant Analysis of Principal Components (DAPC). Consequently, this study suggests that it may be possible to identify the taxonomic source of marine mammal oils based on chemical chemotypes.

The significance of shooting angle in seal shooting.

The present study aimed to investigate the relationship between shooting angle to the head and animal welfare outcomes in the hunt of young harp seals (Pagophilus groenlandicus). The study population consisted of young harp seals belonging to the Greenland Sea harp seal population. A sample of 171, 2-7 weeks old, weaned harp seals of both sexes were included. The study was conducted as an open, randomised parallel group designed trial during the regular hunt. The animals were allocated into four groups, A-D, according to the observed shooting angle to the head, defined as the angle between the direction of the shot and the longitudinal axis of the animal's head: (A) directly from the front; (B) obliquely from the front; (C) directly from the side; and (D) obliquely or directly from behind. Instantaneous death rate (IDR) and time to death (TTD) were the main variables. The mean IDR differed significantly between groups and was highest in group B (96.8%) and lowest in group C (66.7%). For all groups combined it was 84.2%. The mean TTD for seals not rendered instantaneously unconscious or dead (n = 27) differed significantly between groups and was shortest in group A (16 s) and longest in group C (85 s). However, the number of animals included in the TTD analysis was limited. In conclusion, based on the significantly higher IDR, the shooting angle obliquely from the front is recommended to help achieve the best animal welfare outcomes during the hunt of young harp seals.

Surveillance for Zoonotic Pathogens and Inuit Qaujimajatuqangit of Ringed Seals (nattiit) (Pusa hispida) in Frobisher Bay and Eclipse Sound, Nunavut, Canada

Ringed seals (Pusa hispida) (nattiq (s.), nattiit (pl.) [Inuktut]) provide an important food staple for Nunavummiut (Indigenous residents of Nunavut). We studied the health of nattiit harvested by hunters from Baffin Island, Nunavut, via Inuit Qaujimajatuqangit and veterinary science. We conducted serological surveys and polymerase chain reaction (PCR) for select zoonotic pathogens, including Brucella spp., Erysipelothrix rhusiopathiae, Leptospira interrogans, and Toxoplasma gondii, in 55 nattiit from Frobisher Bay (FB) and 58 nattiit from Eclipse Sound (ES). We used a digestion assay to determine the presence of Trichinella spp. larvae in muscle samples from these seals. We conducted interviews with nine Local Knowledge Holders (LKHs) from Iqaluit (FB) and nine from Pond Inlet (ES) to gather their observations about nattiq health. The hunters evaluated nattiq health through a combination of behavior, nutritional condition, and appearance of skin and organs. They rarely observed severely ill nattiit. Hunters from ES but not from FB observed declining nattiit population numbers. In both regions, they observed increased numbers of harp seals (Phoca groenlandica). Frequencies of natural exposure among nattiit from FB and ES, based on seroprevalence, were 20.5% and 37% for Brucella spp., 25% and 11% for E. rhusiopathiae, 93% and 100% for L. interrogans, and 10% and 27% for T. gondii, respectively; PCR was negative for these pathogens in organs and tissues of seropositive animals. We did not detect larvae of Trichinella spp. Knowledge and experience from the LKHs in assessing nattiq health, complemented by negative findings from direct detection methods, provide reassurance about the safety of nattiit as country food, despite their exposure to some zoonotic pathogens in their natural environment.

Multi-decadal trends in biomarkers in harp seal teeth from the North Atlantic reveal the influence of prey availability on seal trophic position.

Arctic food webs are being impacted by borealisation and environmental change. To quantify the impact of these multiple forcings, it is crucial to accurately determine the temporal change in key ecosystem metrics, such as trophic position of top predators. Here, we measured stable nitrogen isotopes (δ15 N) in amino acids in harp seal teeth from across the North Atlantic spanning a period of 60 years to robustly assess multi-decadal trends in harp seal trophic position, accounting for changes in δ15 N at the base of the food web. We reveal long-term variations in trophic position of harp seals which are likely to reflect fluctuations in prey availability, specifically fish- or invertebrate-dominated diets. We show that the temporal trends in harp seal trophic position differ between the Northwest Atlantic, Greenland Sea and Barents Sea, suggesting divergent changes in each local ecosystem. Our results provide invaluable data for population dynamic and ecotoxicology studies.

Sleeping while diving: seals at sea drift in and out of sleep at depth

In mammals, sleep is critical and ubiquitous. However, in marine mammals that spend months or entire lifetimes at sea, sleep can limit access to air and foraging opportunities and leave animals vulnerable to predation. Large, deep-diving northern elephant seals (Mirounga angustirostris) travel thousands of kilometers and spend up to 7 months at sea in search of food. We posited that combined demands to feed and avoid predators would strongly restrict aquatic sleep in seals. We built a portable, non-invasive system to simultaneously monitor electroencephalogram (EEG), electrocardiogram (ECG), three-dimensional motion, and swimming behavior. EEG activity of 13 young (< 3-years-old) female northern elephant seals (N = 5 in the lab, N = 8 in the wild [N = 3 at sea]) revealed that total sleep time was indeed strongly restricted at sea compared to on land (> 6-fold difference; 10.8 ± 3.0 h/day on land, 1.7 ± 0.7 h/day at sea). Seals at sea slept during short naps (< 20 min) while resting on the ocean floor (64-249 m deep) or drifting through the water column (82-377 m deep). REM sleep in mammals co-occurs with sleep paralysis. Our data support the presence of sleep paralysis through a persistent supine inversion (belly-up posture) whenever the seal was in REM (100% of REM sleep in the open ocean). Unexpectedly, elephant seals at sea exhibited a large proportion of REM sleep (29.1 ± 4.3% of at-sea total sleep time), compared to aquatic sleep in captive Caspian seals, harp seals, walruses, and fur seals (11%, 6%, 5%, and 1% respectively). This suggests that sleep at depth allows seals to drift safely in and out of sleep paralysis. However, time for sleep is limited by near-constant foraging to support high energetic demands due to their large body size. The extreme flexibility in sleep duration exhibited by northern elephant seals is unprecedented among mammals – approaching that which is observed in migrating birds. These insights into sleep for a large, highly mobile marine mammal can contribute to our understanding of sleep’s function and pathology across mammals, including humans. Funding: NSF Graduate Resesarch Fellowship, Laurel Clark Sea to Space Physiology Research Grant, ARCS Fellowship, Sooy Graduate Fellowship, National Geographic Early Career Grant, Special Research Grant – UC Santa Cruz, Joint Industry Project (JIP2207-23) [DPC], Office of Naval Research (Grants # N00014-08-1-1195 [DPC], N00014-18-1-2822 [DPC], N00014-00-1-0880 [DPC], N00014-03-1-0651 [DPC], N00014-08-1-1195 [DPC], N00014-20-1-2762 [TMW], N00014-19-1-2178 [TMW]) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

MARINE MAMMALS: MORPHOMETRIC PARAMETERS OF ERYTHROCYTES

Morphological and morphometric parameters of erythrocytes (size, shape and color) were studied in five species of marine mammals. A comparative assessment of oxygen reserves in the blood of the Harp (Pagophilus groenlandicus (Erxleben 1777)) and in Grey seal (Halichoerus grypus (Fabricius 1791)) puppies during adaptations to the aquatic environment, as well as of Bottlenose dolphins during the period of adaptation to captivity conditions is given. Morphometric parameters of red blood cells has been established to vary depending on the age, habitat conditions and phylogenetic position of the animals.

Multispecies discrimination of seals (pinnipeds) using hidden Markov models (HMMs)

Hidden Markov models (HMMs) were developed and implemented for the discrimination of five available Seals (Pinnipeds), namely, the Bearded Seal (Erignathus Barbatus), Harp Seal (Pagophilus Groenlandicus), Leopard Seal (Hydrurga Leptonyx), Ross Seal (Ommatophoca Rossii), and Weddell Seal (Leptonychotes Weddellii). The main objectives of the experiments were to study the impact of the frame size and step size and number of states for feature extraction and acoustic models on classification accuracy. Based on the experimentation using Mel-Frequency Cepstral Coefficients (MFCCs) extracted from the vocalizations (15 ms frame size and 4 ms step size), HMMs containing 20 states with single underlying Gaussian mixture model (GMM) produced discrimination of 95.77%. From the results, the framework could be applied to analysis for other marine mammals for both classification and detection of vocalizations and species.

Environmental DNA metabarcoding reveals seasonal and spatial variation in the vertebrate fauna of Ilulissat Icefjord, Greenland

Ilulissat Icefjord in Greenland is experiencing the effects of climate change, with the Sermeq Kujalleq glacier being one of the fastest-moving and most productive ice streams in Greenland. This is likely affecting the distribution of species in the fjord, including those important to local fisheries. Due to heavy ice conditions, few studies on environmental and ecological conditions exist from the fjord. However, new techniques such as environmental DNA (eDNA) metabarcoding now allow deeper insight into the fjord system. Here, we combine local ecological knowledge with data on hydrographic conditions, stable isotopes (δ18O), and eDNA metabarcoding to investigate the spatial and seasonal distribution of marine fish and mammals inside Ilulissat Icefjord. Our eDNA results support local observations that Arctic char migrate to the southern fjord during summer, harp seals forage in large herds in the fjord system, polar cod is the dominant prey fish in the area, and Greenland shark likely does not reside in the fjord system. Lower predation pressure in the Icefjord, due to the absence of Greenland shark and polar bears as well as limited fishing/hunting, is presumably one of the reasons why ringed seals and Greenland halibut are larger in the Icefjord. Furthermore, our results indicate that in summer, the southern branch of the fjord system has a more diverse community of vertebrates and different water masses than the northern branch and main fjord, indicating a time lag between inflows to the different branches of the fjord system. Our approach highlights the value of combining local ecological knowledge with scientific research and represents a potential starting point for monitoring biological responses in Ilulissat Icefjord associated with climate-induced changes.

Elevated antioxidant defence in the brain of deep-diving pinnipeds.

While foraging, marine mammals undertake repetitive diving bouts. When the animal surfaces, reperfusion makes oxygen readily available for the electron transport chain, which leads to increased production of reactive oxygen species and risk of oxidative damage. In blood and several tissues, such as heart, lung, muscle and kidney, marine mammals generally exhibit an elevated antioxidant defence. However, the brain, whose functional integrity is critical to survival, has received little attention. We previously observed an enhanced expression of several antioxidant genes in cortical neurons of hooded seals (Cystophora cristata). Here, we studied antioxidant gene expression and enzymatic activity in the visual cortex, cerebellum and hippocampus of harp seals (Pagophilus groenlandicus) and hooded seals. Moreover, we tested several genes for positive selection. We found that antioxidants in the first line of defence, such as superoxide dismutase (SOD), glutathione peroxidase (GPX) and glutathione (GSH) were constitutively enhanced in the seal brain compared to mice (Mus musculus), whereas the glutaredoxin and thioredoxin systems were not. Possibly, the activity of the latter systems is stress-induced rather than constitutively elevated. Further, some, but not all members, of the glutathione-s-transferase (GST) family appear more highly expressed. We found no signatures of positive selection, indicating that sequence and function of the studied antioxidants are conserved in pinnipeds.

Multi-dietary tracer approach reveals little overlap in foraging ecology between seasonally sympatric ringed and harp seals in the high Arctic

The rapid rate of climate change in the Arctic is causing broad-scale changes to the physical environment and biological communities. Characterizing the foraging ecology and habitat use of Arctic marine top predators of high ecological and cultural significance is essential to our understanding of their vulnerability to ecosystem change, especially when there is potential for dietary resource competition in spatially co-occurring species. We therefore undertook this study to explore dietary resource competition between seasonally sympatric ringed seals (Pusa hispida) and harp seals (Pagophilus groenlandicus) in Mittimatalik (previously known as Pond Inlet), Nunavut, Canadian Arctic. We used bulk stable isotopes (δ13C and δ15N), fatty acid-specific carbon isotopes (δ13C), fatty acid profiles, and diatom lipid biomarkers in a multi-tracer framework to track carbon and trophic pathways in liver and muscle of both seal species. Altogether, the dietary tracers showed little overlap in the diet between ringed seals and harp seals when they co-occurred in the open-water season in northwest Baffin Bay. Though a high dependence on sea ice-derived carbon sources for both species was found, dietary tracers suggested that ringed seals relied to a far greater extent on sympagic carbon sources (~80% vs. 50% for harp seals) and a greater extent of benthic/coastal prey species compared to the more pelagic feeding harp seals. Ringed seal samples were available year-round, and analyses revealed a clear seasonal pattern of foraging on sympagic and benthic prey during ice-covered months of the year and shifting to greater reliance on pelagic prey during the summer open-water season. Overall, ringed seals may be more vulnerable to changes in sea-ice dynamics in the rapidly changing Arctic than harp seals, though it remains difficult to predict future dietary plasticity and competition between co-occurring top predators in an increasingly ice-free Arctic with a changing prey community.

A retrospective socio‐ecological analysis of seal strandings in the Gulf of Maine

AbstractOver the past several decades, the Gulf of Maine has experienced significant socio‐ecological change. Coastlines have become more densely populated and developed, rapid and dramatic climate change has affected coastal ocean environments, and seal populations have grown as a result of federal protections. Long‐term data sets from marine mammal stranding networks represent a valuable resource for investigating indicator species for coastal ocean health during this period of change. Using data collected from stranded harbor (Phoca vitulina), harp (Pagophilus groenlandicus), and gray (Halichoerus grypus) seals from 2002 to 2017 in Massachusetts, New Hampshire, and Maine, we tested for spatiotemporal correlations between stranding density and human population density, size of and proximity to seal haul‐outs, sea surface temperature, North Atlantic Oscillation, snowfall, and sea ice extent. We found that in the Gulf of Maine proximity to coastal human population centers and large seal haul‐outs are the greatest drivers of reported seal stranding density. Environmental factors played an important role only for harp seals, which do not breed in the study area, although recent shifts in the environmental seascape have the potential to affect all seal species in the Gulf of Maine.

Pup production of Harp Seals in the Northwest Atlantic in 2017 during a time of ecosystem change

Photographic and visual aerial surveys were conducted off Newfoundland and Labrador (”the Front”), and in the Gulf of St. Lawrence (“Gulf”) in March 2017 to estimate pup production of Northwest Atlantic harp seals (Pagophilus groenlandicus). Traditionally, harp seals pup (whelp) in three general areas; the southern Gulf of St. Lawrence, the northern Gulf of St. Lawrence, and off the east coast of Newfoundland and Labrador. After extensive reconnaissance, four whelping areas were identified: one in each of the southern and northern Gulf, and two at the Front. We estimated a total pup production in 2017 of 746,500 (SE=89,900, CV=12%), the lowest since 1994. Most (96%) pups were born at the Front (714,600 pups, SE=89,700). Very few pups were born in the southern Gulf (18,300, SE=1,500) and no whelping concentrations were observed prior to March 5, approximately one week later than previously observed. This is far lower than the 2012 survey estimate of 115,500 (SE=15,100) for the same area. Pup production in the northern Gulf was also lower than in previous years, at 13,600 (SE=3,000). The timing of births in the southern Gulf was much later than normal in 2017, and unusually early pupping at the Front suggests that some females from the Gulf herd may have moved to the Front to whelp due to a lack of ice suitable for pupping (i.e., thin first year) in the Gulf. Harp seals whelp in large concentrations. While one large whelping concentration formed at the Front, approximately 15% of the pupping at the Front occurred in small, dispersed groups which formed later than observed in previous years. Given the unusual ice conditions, distribution of whelping seals, and timing of pupping, assessing the results of the 2017 surveys relative to other estimates of pup production in the Northwest Atlantic is challenging and indicates the ongoing difficulties of assessing a population that is being impacted by climate change.