Pacific Walrus Odobenus Rosmarus Divergens Research Articles

Trichinosis of Marine Mammals in the Territory of Chukotka

Chukotka is the only region of the Russian Federation where traditional fishing of marine mammals, including the gray whale Eschrichtius gibbosus, is conducted. More than 70% of the indigenous population of the coastal settlements of the Chukchi Peninsula eat the meat of marine mammals. Due to the huge distances between communities, lack of infrastructure, limited access to medical and veterinary care, isolated studies of marine mammal infestation with trichinella larvae are being conducted.For the first time, trichinella in the Pacific walrus Odobenus rosmarus divergens in Chukotka were recorded in the coastal zone of the Bering and Chukchi Seas in the 1970s. In the future, trichinosis has not been studied in this region, which confirms the relevance of our work. Infection of marine mammals was studied by trichinelloscopy (compressor and biochemical). Bioassays were collected during fishing by sea St. John's wort in the village of Lorino. Infection rates were determined. Studies conducted on the Chukchi Peninsula confirmed the infection with trichinosis of the Pacific walrus and revealed the larvae of trichinella in lakhtak Erignathus b.nauticus and ringed seal Phoca hispida, and later in larga Phoca largha. The extent of invasion varied from 0.9% in larga to 4.3% in lakhtak. The gray whale is the most popular food item in the diet of the indigenous inhabitants of Chukotka. According to the results of the research, out of 119 individuals of gray whales, trichinella were not found. Given the trophic‐chorological connections of marine mammals, it is difficult to imagine a way of transmission of trichinella in marine ecosystems. However, previously obtained research results allow us to do this. On the Arctic coasts, especially near settlements, there are a large number of corpses of dogs, cats, rats, voles, carcasses of small seals that fall into marine ecosystems. Invertebrates, their adult and larval forms, as well as vertebrates ‐ fish and birds ‐ occupy an important place in the process of disposal of corpses. Studies have shown that various types of invertebrates from 1 to 59 hours, and vertebrates from 28 to 95 hours can be direct or indirect sources of the pathogen of invasion and contribute to their mechanical transfer. Thus, in the conditions of coastal Arctic marine ecosystems, successful circulation of trichinella is carried out, thanks to human economic activity and the specifics of the trophic‐horological relationships of obligate and potential host species. Therefore, monitoring of trichinella invasion in these regions is vital.

Estimating Pacific walrus abundance and survival with multievent mark-recapture models

Arctic marine ecosystems are undergoing rapid physical and biological change associated with climate warming and loss of sea ice. Sea ice loss will impact many species through altered spatial and temporal availability of resources. In the Bering and Chukchi Seas, the Pacific walrus Odobenus rosmarus divergens is one species that could be impacted by rapid environmental change, and thus, population assessments are needed to monitor changes in the status of this ecologically and culturally important marine mammal. We conducted a 5 yr genetic mark-recapture study to estimate demographic parameters for the Pacific walrus. We developed a Bayesian multievent mark-recapture model to estimate walrus survival and abundance while accounting for age misclassification. We estimated the probability of juvenile annual survival as 0.63 (95% credible interval [CrI]: 0.39-0.87) and adult female annual survival as 0.90 (95% CrI: 0.74-1.00). We estimated total abundance as 256434 (95% CrI: 171047-364659). We provide the first estimate of total Pacific walrus abundance since an aerial survey in 2006, which generated a substantially less precise total population size estimate (129000; 95% CI: 55000-507000). The emerging ecosystem state in the northern Bering and Chukchi Seas will likely result in a decline in Pacific walrus abundance, but there is substantial uncertainty regarding the magnitude of the anticipated decline. Our demographic estimates provide critical information to evaluate future population trends of this subsistence resource vital to communities that border the Bering and Chukchi Seas in the USA and Russia.

Evaluating tooth strontium and barium as indicators of weaning age in Pacific walruses.

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 Odobenus rosmarus divergens 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 88Sr and 137Ba 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.

Organochlorine pesticide accumulation in seabirds and marine mammals from the Northwest Pacific

Bioaccumulation of organochlorine pesticides by marine organisms is one of the methods of environmental quality. Concentrations of organochlorine pesticides (HCH isomers (α-, β-, γ-HCH), p,p′-DDT and its metabolites (p,p′-DDD, p,p′-DDE)) in samples of seabirds (Northern fulmar Fulmarus glacialis, Crested auklet Aethia cristatella, Auklet-crumb Aethia pusilla, Pacific gull Larus schistisagus, and Gray petrel Oceanodroma furcate) and marine mammals (Gray whales Eschrichtius robustus and Pacific walrus Odobenus rosmarus divergens) were measured by a GC–MS. The total concentration of OCPs in mammals was higher than in seabirds. Environmental biomonitoring with the use of seabirds and marine mammals, as a long-lived species, is used for global monitoring, since bioaccumulation in these organisms occurs throughout life. The environmental assessment of the Northwest Pacific marine ecosystems revealed that the levels of OCP contamination in this area are similar to the other subarctic regions of the World Ocean.

Influence of climate change on summer-fall distribution of pacific walrus in the western Bering Sea: analysis of reasons and consequences

Recently the sea ice edge at Chukotka retreats further northward in summer and new ice formation begins in a month later in autumn than in previous decades because of climate change that changes the pacific walrus Odobenus rosmarus divergens habitat. Now the Bering Sea becomes completely clear of the ice by start of the spring migration of walruses. In these conditions, the walrus migration routes and feeding grounds location changes. Permanent walrus rookeries on the eastern coast of Chukotka and Kamchatka disappeared (Verkhoturov Island, Karaginsky Island, Bogoslov Islands, Anastasia Bay, Cape Dezhnev, Cape Sery, Cape Olutorsky, Cape Zosima) and new rookeries have formed in the Bering Sea (at Meinypylgino and Enmelen) and on the Arctic shore of Chukotka (at Vankaren and Cape Shmidt). Benthos community has changed, too. As the result, quality of the walrus habitat became worse, the sickness and mortality of young animals increased and the reproduction rate decreased. Formerly stable large walrus rookery in the Krest Bay (Meeskyn) was surveyed in 2016. Together with Retkyn rookery in the Rudder Bay it formed the large Anadyr group of walruses, about 50,000 of the animals gathered on these rookeries in the 1980s. However, the group began to fluctuate with decreasing trend since the 1990s: its number was estimated as 5,000-6,000 animals in 1996, 12,000 in 1997, 30,000 in 1999, 26,000 in 2000, 6,000-8,000 in 2001-2007, 2,000 in 2008. Meeskyn rookery did not function since 2006, though small group of 200 animals was observed here in 2016. Two hypotheses on this tendency are proposed: i) negative influence of climate change on reproduction of walruses in the Chukchi Sea; ii) depletion of the walrus feeding grounds in the Anadyr Bay caused by climate change and excessive abundance of the population.

Bioindicators of Organochlorine Pesticides in the Sea of Okhotsk and the Western Bering Sea.

Organochlorine pesticides (OCPs), such as HCHs and DDTs, are still used as pesticides in the Southern Hemisphere and can reach the North Pacific due to long range atmospheric transfer. Marine mammals (Pacific walrus Odobenus rosmarus divergens, gray whale Eschrichtius robustus), the seabirds (Pacific gull Larus schistisagus, crested auklet Aethia cristatella, auklet crumb Aethia pusilla, northern fulmar Fulmarus glacialis, and grey petrel Oceanodroma furcata) and Pacific salmon (pink Oncorhynchus gorbuscha, chum O. keta, chinook O. tshawytscha, and sockeye O. nerka) were collected near the Kuril Islands (the northern-western part of the Pacific Ocean), in the Sea of Okhotsk and the Bering Sea. The total OCPs concentration (HCHs+DDTs) was found in each organism, including the Pacific walrus (70-90,263ng/g lipid), the seabirds (29-16,095ng/g lipid), and the Pacific salmon (41-7103ng/g lipid). The concentrations and possible sources of OCPs in marine organisms as biological indicators are discussed.

Abundance and distribution of pacific walrus <i>Odobenus rosmarus divergens</i> in vicinity of Cape Serdtse-Kamen in 2009-2013

Results of the first special research of pacific walrus Odobenus rosmarus divergens at Cape Serdtse-Kamen conducted in the 2009-2011 and 2013 are presented. The coastal haulout place looks as series of relatively isolated areas (up to 36) located alongshore about 20 km from Cape Serdtse-Kamen to the Ikalyurynveem River mouth. Initially the walruses were on the northwestern edge of the haulout place between Cape Serdtse-Kamen and Cape Sulyn but expanded southeastward with increasing of their number. In the years with early and intense ice melting, the walruses come to the area in early September, and the haulout forms to the end of the first 10-day period of this month. In conditions of late ice retreat, as in the 2013, the walruses on the whole come to Cape Serdthse-Kamen later. The maximum number of walruses in this area was observed in 2009 (about 98,000 animals) and 2010 (118,500). This is the record number of walruses ever recorded simultaneously on one coastal haulout in the species range. Almost the whole Pacific population gathers in the vicinity of Cape Serdtse-Kamen for feeding in late autumn and continues to feed there until freezing of the Chukchi Sea. In spite of obvious significance of the area at Cape Serdtse-Kamen for the pacific walrus population, there still aren’t any special measures of their protection in this part of the coast when they are ashore - the measures are definitely necessary to prevent intensive economic activities in this key for the walruses area and to save the coastal haulout for traditional use of native people.

Persistent toxic substances in the muscles and liver of the pacific walrus Odobenus rosmarus divergens Illiger, 1815 from the Bering Sea

This study reports data on the contents of organochlorine pesticides and heavy metals in the muscles and livers of eight individuals (five males and three females) of the Pacific walrus Odobenus rosmarus divergens Illiger, 1815, which were captured in the summer of 2011 in Mechigmensky Bay of the Bering Sea. Pesticides, namely α-, β-, and γ-isomers of hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT) and its metabolites dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE), as well as the heavy metals Cd, Pb, and Hg were found in all samples studied. The total concentration of organochlorine pesticides in the muscles varied from 200 to 5700 ng/g lipid weight and in the liver from 4900 to 90300 ng/g lipid weight. The concentrations of cadmium, lead, and mercury were 0.04–6.7, 0.13–0.76, and 0.03–0.40 μg/g dry weight, respectively. On the whole, the contents of organochlorine pesticides and heavy metals in the organs of the Pacific walrus were lower compared to those in marine mammals from other regions of the World Ocean.

The influence of ice conditions on terrestrial haulouts of the pacific walrus Odobenus rosmarus divergens Illiger, 1815 in the Gulf of Anadyr, Bering Sea

The boundaries of the area of appropriate depths for feeding by the Pacific walrus were determined. Based on the ice maps for the period of 1997–2011, the long-term dynamics of ice breakup and formation in the Gulf of Anadyr (Bering Sea) were analyzed. There was a tendency towards a reduction in the ice-cover period in the Gulf of Anadyr, especially during 2007–2011. In 2008, the number and duration of stay of walruses at terrestrial haulout sites on Meeskyn Spit Island and on Retkyn Spit continued to decrease. Walruses also used other haulouts located in the Gulf of Anadyr at Cape Gek and Cape Retkyn. The age and sex structure of the walrus herd changed: the proportions of adult males and young animals decreased, while the proportion of females with calves increased.

Bioenergetics model for estimating food requirements of female Pacific walruses Odobenus rosmarus divergens

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 460:261-275 (2012) - DOI: https://doi.org/10.3354/meps09706 Bioenergetics model for estimating food requirements of female Pacific walruses Odobenus rosmarus divergens S. R. Noren1,*, M. S. Udevitz2, C. V. Jay2 1Institute of Marine Science, University of California, Santa Cruz, Santa Cruz, California 95060, USA 2US Geological Survey, Alaska Science Center, Anchorage, Alaska 99508, USA *Email: snoren@biology.ucsc.edu ABSTRACT: Pacific walruses Odobenus rosmarus divergens use sea ice as a platform for resting, nursing, and accessing extensive benthic foraging grounds. The extent of summer sea ice in the Chukchi Sea has decreased substantially in recent decades, causing walruses to alter habitat use and activity patterns which could affect their energy requirements. We developed a bioenergetics model to estimate caloric demand of female walruses, accounting for maintenance, growth, activity (active in-water and hauled-out resting), molt, and reproductive costs. Estimates for non-reproductive females 0–12 yr old (65−810 kg) ranged from 16359 to 68960 kcal d−1 (74−257 kcal d−1 kg−1) for years with readily available sea ice for which we assumed animals spent 83% of their time in water. This translated into the energy content of 3200–5960 clams per day, equivalent to 7–8% and 14–9% of body mass per day for 5–12 and 2–4 yr olds, respectively. Estimated consumption rates of 12 yr old females were minimally affected by pregnancy, but lactation had a large impact, increasing consumption rates to 15% of body mass per day. Increasing the proportion of time in water to 93%, as might happen if walruses were required to spend more time foraging during ice-free periods, increased daily caloric demand by 6–7% for non-lactating females. We provide the first bioenergetics-based estimates of energy requirements for walruses and a first step towards establishing bioenergetic linkages between demography and prey requirements that can ultimately be used in predicting this population’s response to environmental change. KEY WORDS: Pinniped · Foraging · Metabolism · Energetics · Arctic · Ice · Climate change Full text in pdf format PreviousNextCite this article as: Noren SR, Udevitz MS, Jay CV (2012) Bioenergetics model for estimating food requirements of female Pacific walruses Odobenus rosmarus divergens. Mar Ecol Prog Ser 460:261-275. https://doi.org/10.3354/meps09706 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 460. Online publication date: July 24, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.

Walrus areas of use in the Chukchi Sea during sparse sea ice cover

The Pacific walrus Odobenus rosmarus divergens feeds on benthic invertebrates on the con- tinental shelf of the Chukchi and Bering Seas and rests on sea ice between foraging trips. With climate warming, ice-free periods in the Chukchi Sea have increased and are projected to increase further in fre- quency and duration. We radio-tracked walruses to estimate areas of walrus foraging and occupancy in the Chukchi Sea from June to November of 2008 to 2011, years when sea ice was sparse over the conti- nental shelf in comparison to historical records. The earlier and more extensive sea ice retreat in June to September, and delayed freeze-up of sea ice in Octo- ber to November, created conditions for walruses to arrive earlier and stay later in the Chukchi Sea than in the past. The lack of sea ice over the continental shelf from September to October caused walruses to forage in nearshore areas instead of offshore areas as in the past. Walruses did not frequent the deep waters of the Arctic Basin when sea ice retreated off the shelf. Walruses foraged in most areas they occu- pied, and areas of concentrated foraging generally corresponded to regions of high benthic biomass, such as in the northeastern (Hanna Shoal) and south- western Chukchi Sea. A notable exception was the occurrence of concentrated foraging in a nearshore area of northwestern Alaska that is apparently de - pauperate in walrus prey. With increasing sea ice loss, it is likely that walruses will increase their use of coastal haul-outs and nearshore foraging areas, with consequences to the population that are yet to be understood.

Observations on keeping the Pacific walrus Odobenus rosmarus divergens at Hanover Zoo

Observations on keeping the Pacific walrus Odobenus rosmarus divergens at Hanover Zoo