New migration and distribution patterns of Atlantic walruses (Odobenus rosmarus rosmarus) around Nunavik (Quebec, Canada) identified using Inuit Knowledge
ABSTRACT: Environmental changes are affecting the Arctic at an unprecedented rate, but limited scientific knowledge exists on their impacts on species such as walruses (Odobenus rosmarus). Inuit Traditional and Local Ecological Knowledge (Inuit TEK/LEK) held by Inuit walrus harvesters could shed light on walrus ecology and related environmental changes. Our main objective was to study spatial and temporal changes in Atlantic walrus (Odobenus rosmarus rosmarus) distribution in Nunavik (northern Québec, Canada) using Inuit TEK/LEK. To do so, we documented the knowledge and observations of 33 local hunters and Elders as part of a larger project on Atlantic walruses in Nunavik. We first gathered information on changes in Inuit land use patterns and harvesting practices through time and space, which was a crucial step to avoid potential biases in interpreting local observations on walrus distribution. We found that walrus hunters are now covering smaller hunting areas over shorter time periods, reducing in space and time their observations of Atlantic walruses around Nunavik. While clearly taking these limitations into account, we learned from interviews that some areas abandoned by Atlantic walruses in the past were now being re-occupied. Importantly, Atlantic walruses, which migrate following the melting ice, are now traveling along the eastern coast of Nunavik one month earlier, suggesting that Atlantic walrus migration has changed due to variations in sea-ice coverage around Nunavik. Our study not only highlighted important changes in Atlantic walrus distribution and migration in Nunavik, but also sheds light on the importance of documenting temporal and spatial changes in Inuit land use patterns and harvesting practices to understand the ecology of Arctic species using Inuit Knowledge.
The online version contains supplementary material available at 10.1007/s00300-021-02920-6.
Project description:Walruses, Odobenus rosmarus, play a key role in the Arctic ecosystem, including northern Indigenous communities, which are reliant upon walruses for aspects of their diet and culture. However, walruses face varied environmental threats including rising sea-water temperatures and decreasing ice cover. An underappreciated threat may be the large amount of solar ultraviolet radiation (UV) that continues to reach the Arctic as a result of ozone loss. UV has been shown to negatively affect whales. Like whales, walrus skin is unprotected by fur, but in contrast, walruses spend long periods of time hauled-out on land. In this study, we combined the results of histological analyses of skin sections from five Atlantic walruses, Odobenus rosmarus rosmarus, collected in Nunavik (Northern Quebec, Canada) with qualitative data obtained through the interviews of 33 local walrus hunters and Inuit Elders. Histological analyses allowed us to explore UV-induced cellular lesions and interviews with experienced walrus hunters and Elders helped us to study the incidences and temporal changes of UV-induced gross lesions in walruses. At the microscopic scale, we detected a range of skin abnormalities consistent with UV damage. However, currently such UV effects do not seem to be widely observed at the whole-animal level (i.e., absence of skin blistering, erythema, eye cataract) by individuals interviewed. Although walruses may experience skin damage under normal everyday UV exposure, the long-term data from local walrus hunters and Inuit Elders did not report a relation between the increased sun radiation secondary to ozone loss and walrus health.
Project description:The population size of Atlantic walruses (Odobenus rosmarus rosmarus) is depleted relative to historical abundance levels. In Svalbard, centuries of over-exploitation brought the walrus herds to the verge of extinction, and such bottlenecks may have caused loss of genetic variation. To address this for Svalbard walruses, mitochondrial haplotypes of historical walruses from two major haul-out sites, Bjørnøya and Håøya, within the Archipelago were explored using bone samples from animals killed during the peak period of harvesting.Using ancient DNA methodologies, the mitochondrial NADH dehydrogenase 1 (ND1) gene, the cytochrome c oxidase 1 (COI) gene, and the control region (CR) were targeted for 15 specimens from Bjørnøya (of which five were entirely negative) and 9 specimens from Håøya (of which one was entirely negative). While ND1 and COI sequences were obtained for only a few samples, the CR delivered the most comprehensive data set, and the average genetic distance among historic Svalbard samples was 0.0028 (SD = 0.0023).The CR sequences from the historical samples appear to be nested among contemporary Atlantic walruses, and no distinct mitochondrial haplogroups were identified in the historical samples that may have been lost during the periods of extensive hunting. However, given the low sample size and poor phylogenetic resolution it cannot be excluded that such haplogroups existed.
Project description:Abstract Pacific walruses (Odobenus rosmarus divergens) play a vital role in Arctic marine ecosystems and the subsistence lifestyle of Alaska Native communities. Museum collections contain numerous archaeological and historic walrus specimens that have proven useful in a variety of studies; however, for many cases, the sex of these specimens is unknown. Sexes of adult (> 5 years determined by tooth aging) Atlantic walruses (Odobenus rosmarus rosmarus) have been accurately determined in previous studies using mandible measurements. We tested the validity of this approach for Pacific walruses, and used full fusion of the mandibular symphysis to define adults. Using high precision digital calipers (± 0.01 mm), four measurements were taken either on the left or right side of 91 walrus mandibles: 80 modern mandibles (70 known-sex specimens; 10 unknown-sex specimens) and 11 archaeological mandibles of unknown sex. We used linear discriminant function analysis (LDFA) to determine what measurements best distinguished Pacific walrus males from females. Minimum mandible thickness had the most predictive power, whereas mandible length, height, and depth, were less predictive. Posterior probabilities indicated that LDFA classified the known-sex Pacific walruses with 100% accuracy, and unknown sex with ? 90% probability. The ability to define the sex of unknown individuals accurately could greatly increase the sample size of future projects dealing with skeletal remains, and will improve future research efforts.
Project description:BACKGROUND: Direct observations of underwater behaviour of free-living marine mammals are rare. This is particularly true for large and potentially dangerous species such as the walrus (Odobenus rosmarus). Walruses are highly specialised predators on benthic invertebrates - especially bivalves. The unique feeding niche of walruses has led to speculations as to their underwater foraging behaviour. Based on observations of walruses in captivity and signs of predation left on the sea floor by free-living walruses, various types of feeding behaviour have been suggested in the literature. In this study, however, the underwater feeding behaviour of wild adult male Atlantic walruses (O. r. rosmarus) is documented for the first time in their natural habitat by scuba-divers. The video recordings indicated a predisposition for use of the right front flipper during feeding. This tendency towards dextrality was explored further by examining a museum collection of extremities of walrus skeletons. RESULTS: During July and August 2001, twelve video-recordings of foraging adult male walruses were made in Young Sound (74 degrees 18 N; 20 degrees 15 V), Northeast Greenland. The recordings did not allow for differentiation among animals, however based on notes by the photographer at least five different individuals were involved. The walruses showed four different foraging behaviours; removing sediment by beating the right flipper, removing sediment by beating the left flipper, removing sediment by use of a water-jet from the mouth and rooting through sediment with the muzzle. There was a significant preference for using right flipper over left flipper during foraging. Measurements of the dimensions of forelimbs from 23 walrus skeletons revealed that the length of the right scapula, humerus, and ulna was significantly greater than that of the left, supporting our field observations of walruses showing a tendency of dextrality in flipper use. CONCLUSION: We suggest that the four feeding behaviours observed are typical of walruses in general, although walruses in other parts of their range may have evolved other types of feeding behaviour. While based on small sample sizes both the underwater observations and skeletal measurements suggest lateralized limb use, which is the first time this has been reported in a pinniped.
Project description:The expected reduction of ice algae with declining sea ice may prove to be detrimental to the Pacific Arctic ecosystem. Benthic organisms that rely on sea ice organic carbon (iPOC) sustain benthic predators such as the Pacific walrus (Odobenus rosmarus divergens). The ability to track the trophic transfer of iPOC is critical to understanding its value in the food web, but prior methods have lacked the required source specificity. We analyzed the H-Print index, based on biomarkers of ice algae versus phytoplankton contributions to organic carbon in marine predators, in Pacific walrus livers collected in 2012, 2014 and 2016 from the Northern Bering Sea (NBS) and Chukchi Sea. We paired these measurements with stable nitrogen isotopes (δ15N) to estimate trophic position. We observed differences in the contribution of iPOC in Pacific walrus diet between regions, sexes, and age classes. Specifically, the contribution of iPOC to the diet of Pacific walruses was higher in the Chukchi Sea (52%) compared to the NBS (30%). This regional difference is consistent with longer annual sea ice persistence in the Chukchi Sea. Within the NBS, the contribution of iPOC to walrus spring diet was higher in females (~45%) compared to males (~30%) for each year (p < 0.001), likely due to specific foraging behavior of females to support energetic demands associated with pregnancy and lactation. Within the Chukchi Sea, the iPOC contribution was similar between males and females, yet higher in juveniles than in adults. Despite differences in the origin of organic carbon fueling the system (sea ice versus pelagic derived carbon), the trophic position of adult female Pacific walruses was similar between the NBS and Chukchi Sea (3.2 and 3.5, respectively), supporting similar diets (i.e. clams). Given the higher quality of organic carbon from ice algae, the retreat of seasonal sea ice in recent decades may create an additional vulnerability for female and juvenile Pacific walruses and should be considered in management of the species.
Project description:The Pacific walrus (<i>Odobenus rosmarus divergens</i>) is an iconic Arctic marine mammal and an important resource to many Alaska Natives. A decrease in sea ice habitat and unknown population numbers has led to concern of the long-term future health of the walrus population. There is currently no clear understanding of how walrus physiology might be affected by a changing Arctic ecosystem. In this study, steroid hormone concentrations (progesterone, testosterone, cortisol and estradiol) were analysed in walrus bones collected during archaeological [3585-200 calendar years before present (BP)], historical [1880-2006 common era (CE)] and modern (2014-2016 CE) time periods, representing ~?3651 years, to track changes in reproductive activity and cortisol concentrations (biomarker of stress) over time. Our results show that modern walrus samples have similar cortisol concentrations (median?=?43.97?±?standard deviation 904.38 ng/g lipid) to archaeological walruses (38.94?±?296.17 ng/g lipid, <i>P</i>?=?0.75). Cortisol concentrations were weakly correlated with a 15-year average September Chukchi Sea ice cover (<i>P</i>?=?0.002, 0.02, <i>r</i> <sup>2</sup>?=?0.09, 0.04, for females and males, respectively), indicating a possible physiological resiliency to sea ice recession in the Arctic. All steroid hormones had significant negative correlations with mean walrus population estimates from 1960 to 2016 (<i>P</i>?<?0.001). Progesterone in females and testosterone in males exhibited significant correlations with average September Chukchi Sea ice cover for years 1880-2016 (<i>P</i>?<?0.001 for both, <i>r<sup>2</sup></i> ?=?0.34, 0.22, respectively). Modern walruses had significantly lower (<i>P</i>?=?<?0.001) reproductive hormone concentrations compared with historic walruses during times of rapid population increase, indicative of a population possibly at carrying capacity. This is the first study to apply bone as a tool to monitor long-term changes in hormones that may be associated with changes in walrus population size and sea ice cover.
Project description:The modern walrus, Odobenus rosmarus, is specialized and only extant member of the family Odobenidae. They were much more diversified in the past, and at least 16 genera and 20 species of fossil walruses have been known. Although their diversity increased in the late Miocene and Pliocene (around 8-2 Million years ago), older records are poorly known. A new genus and species of archaic odobenid, Archaeodobenus akamatsui, gen. et sp. nov. from the late Miocene (ca. 10.0-9.5 Ma) top of the Ichibangawa Formation, Hokkaido, northern Japan, suggests rapid diversification of basal Miocene walruses. Archaeodobenus akamatsui is the contemporaneous Pseudotaria muramotoi from the same formation, but they are distinguishable from each other in size and shape of the occipital condyle, foramen magnum and mastoid process of the cranium, and other postcranial features. Based on our phylogenetic analysis, A. akamatsui might have split from P. muramotoi at the late Miocene in the western North Pacific. This rapid diversification of the archaic odobenids occurred with a combination of marine regression and transgression, which provided geological isolation among the common ancestors of extinct odobenids.
Project description:Lactation length and weaning age provide important information about maternal investment, which can reflect the health and nutritional status of the mother, as well as broader reproductive strategies in mammals. Calcium-normalized strontium (Sr) and barium (Ba) concentrations in the growth layers of mammalian teeth differ for nursing animals and those consuming non-milk foods, thus can be used to estimate age-at-weaning. To date, this approach has been used only for terrestrial animals, and almost exclusively for primates.The goal of this study was to determine whether Sr and Ba concentrations in the cementum of Pacific walrus <i>Odobenus rosmarus divergens</i> teeth can be used to estimate weaning age. Teeth from 107 walruses were analysed using laser ablation inductively coupled plasma mass spectrometry, and calcium-normalized <sup>88</sup>Sr and <sup>137</sup>Ba concentrations were quantified.For most walruses, both Sr and Ba concentrations exhibited rapid changes in early life. Ba concentrations matched closely with expected patterns in the published literature, rapidly declining from high to low concentrations (typically from ~10 ppm to ~5 ppm). In contrast, Sr exhibited a pattern opposite to that presented in studies of terrestrial mammals, appearing nearly identical to Ba (typically declining from ~400 ppm to ~200 ppm). To explain these findings, we present conceptual models of the factors generating weaning signals in Sr and Ba for terrestrial mammals, as well as a new, hypothetical model for walruses. Both a visual and mathematical approach to weaning age estimation indicated a median weaning age of walruses at the end of the second year of life (in the second dark layer of the tooth cementum), with many walruses estimated to have weaned in their third year of life, and a smaller group weaning in their fourth or fifth year. This is later than expected, given a published estimate of walrus weaning at 18-24 months.These results do not conclusively support the use of tooth Sr and Ba for estimating weaning age in walruses, and further research is warranted to better understand the drivers of the observed patterns of Ba and Sr accumulation in walrus teeth.
Project description:Whisker touch is an active sensory system. Previous studies in Pinnipeds have adopted relatively stationary tasks to judge tactile sensitivity, which may not accurately promote natural whisker movements and behaviours. This study developed a novel feeding task, termed fish sweeping to encourage whisker movements. Head and whisker movements were tracked from video footage in Harbor seal (Phoca vitulina), California sea lion (Zalophus californianus) and Pacific walrus (Odobenus rosmarus divergens). All species oriented their head towards the moving fish target and moved their whiskers during the task. Some species also engaged in whisker control behaviours, including head-turning asymmetry in the Pacific walrus, and contact-induced asymmetry in the Pacific walrus and California sea lion: behaviours that have only previously been observed in terrestrial mammals. This study confirms that Pinnipeds should be thought of as whisker specialists, and that whisker control (movement and positioning) is an important aspect of touch sensing in these animals, especially in sea lions and walruses. That the California sea lion controls whisker movement in relation to an object, and also had large values of whisker amplitude, spread and asymmetry, suggests that California sea lions are a promising model with which to further explore active touch sensing.
Project description:Species biogeography is a result of complex events and factors associated with climate change, ecological interactions, anthropogenic impacts, physical geography, and evolution. To understand the contemporary biogeography of a species, it is necessary to understand its history. Specimens from areas of localized extinction are important, as extirpation of species from these areas may represent the loss of unique adaptations and a distinctive evolutionary trajectory. The walrus (Odobenus rosmarus) has a discontinuous circumpolar distribution in the arctic and subarctic that once included the southeastern Canadian Maritimes region. However, exploitation of the Maritimes population during the 16th-18th centuries led to extirpation, and the species has not inhabited areas south of 55°N for ?250 years. We examined genetic and morphological characteristics of specimens from the Maritimes, Atlantic (O. r. rosmarus) and Pacific (O. r. divergens) populations to test the hypothesis that the first group was distinctive. Analysis of Atlantic and Maritimes specimens indicated that most skull and mandibular measurements were significantly different between the Maritimes and Atlantic groups and discriminant analysis of principal components confirmed them as distinctive groups, with complete isolation of skull features. The Maritimes walrus appear to have been larger animals, with larger and more robust tusks, skulls and mandibles. The mtDNA control region haplotypes identified in Maritimes specimens were unique to the region and a greater average number of nucleotide differences were found between the regions (Atlantic and Maritimes) than within either group. Levels of diversity (h and ?) were lower in the Maritimes, consistent with other studies of species at range margins. Our data suggest that the Maritimes walrus was a morphologically and genetically distinctive group that was on a different evolutionary path from other walrus found in the north Atlantic.