Remarks on the Distribution and Natural History of Pagophilic Pinnipeds in the Bering and Chukchi Seas
TL;DR: Differences in body structure, ecological adaptation, and behavior in relation to distribution of the five pagophilic pinnipeds in the Bering and Chukchi seas are discussed.
Abstract: Five species of pagophilic (ice-loving) pinnipeds live in the Bering and Chukchi seas: Odobenus rosmarus, Phoca (Pusa) hispida, Phoca (Histriophoca) fasciata, an ice-breeding population of Phoca (Phoca) vitulina, and Erignathus barbatus Breeding adults of these species are mostly separated from each other during late winter and early spring, when, throughout the pupping and subsequent mating periods, P vitulina and P fasciata occupy the edge-zone of the seasonal pack ice, E barbatus and O rosmarus are mainly farther north within the heavier pack ice, and P hispida occupies areas of extensive land-fast ice This paper discusses differences in body structure, ecological adaptation, and behavior in relation to distribution of the five species
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TL;DR: Based on a pan-Arctic quantitative index of species sensitivity to climate change, the hooded seal, the polar bear, and the narwhal appear to be the three most sensitive Arctic marine mammal species, primarily due to reliance on sea ice and specialized feeding.
Abstract: We review seven Arctic and four subarctic marine mammal species, their habitat requirements, and evidence for biological and demographic responses to climate change. We then describe a pan-Arctic quantitative index of species sensitivity to climate change based on population size, geographic range, habitat specificity, diet diversity, migration, site fidelity, sensitivity to changes in sea ice, sensitivity to changes in the trophic web, and maximum population growth potential (Rmax). The index suggests three types of sensitivity based on: (1) narrowness of distribution and specialization in feeding, (2) seasonal dependence on ice, and (3) reliance on sea ice as a structure for access to prey and predator avoidance. Based on the index, the hooded seal, the polar bear, and the narwhal appear to be the three most sensitive Arctic marine mammal species, primarily due to reliance on sea ice and specialized feeding. The least sensitive species were the ringed seal and bearded seal, primarily due to large circumpolar distributions, large population sizes, and flexible habitat requirements. The index provides an objective framework for ranking species and focusing future research on the effects of climate change on Arctic marine mammals. Finally, we distinguish between highly sensitive species and good indicator species and discuss regional variation and species-specific ecology that confounds Arctic-wide generalization regarding the effects of climate change.
633 citations
Cites background from "Remarks on the Distribution and Nat..."
...—Bearded seals are widely distributed throughout the circumpolar Arctic, mainly over the relatively shallower waters of the continental shelf and usually in association with moving ice or shore leads and polynyas (Burns 1970; Fig....
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...…the land-fast ice over the continental shelf along Arctic coasts, bays, and interisland channels (Smith and Hammill 1981), they may also be abundant and have pups in drifting pack ice both nearshore and offshore (Burns 1970, Finley et al. 1983, Smith 1987, Wiig et al. 1999, Lydersen et al. 2004)....
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...These species partition their use of sea ice habitats either through direct habitat selection or seasonal migrations coinciding with changing sea ice conditions (Burns 1970; Fig....
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...There is little information on the specific characteristics of ice preferences other than general descriptions (Burns 1970, Simpkins et al. 2003)....
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...However, in the Bering and Chukchi seas, many bearded seals make well-defined seasonal movements to maintain association with ice year-round (Burns 1970)....
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01 Jan 1987
TL;DR: The bulk of a female’s reproductive expenditure is in an environment in which she cannot feed and the temporal separation of feeding and lactation is achieved by a wide range of behavioral, physiological, and anatomic adaptations.
Abstract: Lactation represents a major proportion of maternal reproductive effort In ungulates the energetic costs of lactation comprise 75–80% of the total energetic costs of reproduction (Oftedal, 1985) Although pinnipeds feed at sea, they return to land or ice to give birth and to nurse their young (Fig 1) (Bonner, 1984) Thus, the bulk of a female’s reproductive expenditure is in an environment in which she cannot feed The temporal separation of feeding and lactation is achieved by a wide range of behavioral, physiological, and anatomic adaptations
299 citations
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TL;DR: This review presents summary figures of, and fits growth curves to, data on body lengths (as standard length, SL, whenever possible) of pinnipeds at ages estimated to O.I y, and the Baikal seal is confirmed as the smallest species ofpinniped.
Abstract: This review presents summary figures of, and fits growth curves to, data on body lengths (as standard length, SL, whenever possible) of pinnipeds at ages estimated to O.I y. (1) Generalized von Bertalanffy (vB) growth curves are fitted to most data: Lx = L infinity (I - ea(x-x0)b, Lx is length at age x, x0 is the origin of the curve (here chosen a priori as time of initiation of embryonic growth), L infinity is asymptotic length, a (which is negative) determines rate of approach to the asymptote, and b influences the 'shape' of the approach. (2) No single monotonic growth equation suffices for growth in length, which is linear before birth and remains so during early life. The vB equation is only suitable to describe mean lengths of newborns, and animals one or more years old. (3) Also, for males of polygynous species, two functions are needed to account for accelerated growth at puberty. Generally a Gompertz equation is adequate for adult males of these species. (4) The fitted growth equations permit statistical comparisons of sizes and growth rates, as well as of individual variability (as growth-curve residuals), among populations and species. (5) For the following species (including different populations when available), the reliability of data is assessed and parameters of growth curves are presented (with sexes separated where significantly different): walrus, California and Steller sea lions, Antarctic, subantarctic and northern fur seals, Hawaiian monk seal, crabeater, Weddell and Leopard seals, southern and northern elephant seals, bearded, hooded, ringed, Baikal, Caspian, spotted, harbour, harp, ribbon and grey seals. (6) Some novel findings pertain to individual species as follows. Although the Pacific walrus is generally stated to be the larger subspecies, females from Hudson Bay and males from Foxe Basin, in the eastern Canadian Arctic, may be as long as those from the Bering Sea. Although female Weddell seals have been assumed to grow larger than males, there is no significant difference in growth curves fitted to the most complete data. Uniquely among populations examined, the relative variability (absolute growth curve residuals/predicted lengths) of male southern elephant seals is amplified with age. Among ringed seals from Svalbard, the eastern, western and high Canadian Arctic, and the Bering, Chukchi, Okhotsk, Barents and Baltic Seas, asymptotic sizes are larger among those that breed on land-fast ice rather than floes, and size may be more variable in more extreme Arctic environments. The Baikal seal is confirmed as the smallest species of pinniped.(ABSTRACT TRUNCATED AT 400 WORDS)
262 citations
TL;DR: A brief lactation period with rapid neonatal weight gain may be adaptive for seals breeding on unstable pack ice and the duration of lactation and growth of known-age pups of the hooded sea...
Abstract: A brief lactation period with rapid neonatal weight gain may be adaptive for seals breeding on unstable pack ice. We studied the duration of lactation and growth of known-age pups of the hooded sea...
181 citations
TL;DR: Canadian ringed seals were depleted in 13C compared to Alaskan pinnipeds, likely because of Beaufort Sea versus Chukchi and Bering seas influence.
Abstract: Feeding habits of ringed (Phoca hispida), bearded (Erignathus barbatus), spotted (Phoca largha) and ribbon (Phoca fasciata) seals and walrus (Odobenus rosmarus) were studied using stomach contents and stable carbon and nitrogen isotopes. Bearded seals fed benthically, primarily crustaceans and mollusks. Both zooplankton and fish were significant prey for ringed seals, while fish was principal spotted seal prey. Few gastric contents were available from ribbon seals. δ15N was positively correlated with age in ribbon seals and δ13C was positively correlated with age in ringed and ribbon seals. δ15N was highest in spotted seals, in agreement with their fish-dominated diet. δ15N was not different between Alaskan-harvested ringed and bearded seals, while δ15N was lowest in ribbon seals and walrus. Carbon-13 was most enriched in bearded seals and walrus reflecting benthic ecosystem use. Canadian ringed seals were depleted in 13C compared to Alaskan pinnipeds, likely because of Beaufort Sea versus Chukchi and Bering seas influence.
168 citations
Cites background or result from "Remarks on the Distribution and Nat..."
...They are commonly referred to as ice or pagophilic seals, but are adapted to different niches within the sea ice environment, and only some overlap occurs among species (Burns 1970; Simpkins et al. 2003)....
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...This is in agreement with pelagic feeding behavior of ribbon seals during the ice-free months (Burns 1970)....
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...with pelagic feeding behavior of ribbon seals during the ice-free months (Burns 1970)....
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References
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41 citations
DOI•
01 Jan 1955
TL;DR: The Pacific walrus inhabits the Bering Sea during winter and the Chukchee Sea in summer, generally in close association with sea ice as discussed by the authors, where the animals frequent waters of less than 50 fathoms depth in which their preferred food, the pelecypods Mya, Saxicava, Astarte, Macoma and Clinocardium occur.
Abstract: The Pacific walrus inhabits the Bering Sea during winter and the Chukchee Sea in summer, generally in close association with sea ice. The year-round northern limit to this range is marked by the southern edge of the relatively unbroken pack ice which, though not impenetrable, is usually avoided. The southern limit appears to be set by air temperatures, regions with monthly means of 50 F or more being unoccupied. Between these two "barriers," the animals frequent waters of less than 50 fathoms depth in which their preferred food, the pelecypods Mya, Saxicava, Astarte, Macoma, and Clinocardium occur. Seasonal migrations between the Bering and Chukchee Seas appear to be partly in response to changing physical conditions and partly due to an innate or learned behaviour pattern. Females are the most regular migrants; males are more subject to the inconsistencies of ice drift. The bull Pacific walrus reaches sexual maturity at six to eight years of age, the cow at four.to five years of age. Breeding takes place mostly from April to June as the animals are migrating northward , and there is no evidence of any organized polygamy or "harem breeding." Gestation is one full year, and twinning is unknown. An individual cow rarely conceives in successive years, the first three pregnancies generally being at 2-year intervals and later ones three or more years apart. Males become senile at about fifteen years of age. Full adult body size is achieved at four to six years of age by both sexes, though growth continues slowly thereafter. The tusks and other teeth grow at a relatively high rate throughout the life span, and analyses of their structure and size have yielded good techniques for age determination. The population, upwards of 40,000 animals at present, has declined slightly in the past fifteen years, but it has reached or is approaching equilibrium. The birth rate and death rate are about equal, human predation accounting for most of the latter. Since the population is currently too small to satisfy the Alaskan Eskimos' needs, it is recommended that it be permitted to increase by eliminating some of the wasteful hunting practices which are now in effect.
9 citations
01 May 1964
TL;DR: In this article, the authors describe in great detail the procedures and techniques hitherto developed in provision of short-term ice forecasts, and the procedures are formulated for application; all ice features to be predicted are correlated with known or readily predictable environmental variables.
Abstract: : The intent of this manual is to describe in as great detail as possible the procedures and techniques hitherto developed in provision of short- term ice forecasts. The procedures are formulated for application; all ice features to be predicted are correlated with known or readily predictable environmental variables.
8 citations