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Robert L. Brownell - One of the best experts on this subject based on the ideXlab platform.
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Genetic Differentiation Between Western and Eastern (Eschrichtius robustus) Gray Whale Populations Using Microsatellite Markers
2020Co-Authors: Aimee R Lang, Robert L. Brownell, David W Weller, Alexander M Burdin, Richard G Leduc, Jr 4Abstract:ABSTRACT Within the North Pacific, gray whales (Eschrichtius robustus) are recognized as distinct eastern and western populations. Although both populations were severely reduced by whaling, the eastern population is generally considered to have recovered while the western population has remained highly depleted. Previous studies have documented genetic differentiation between the two populations on the basis of mtDNA haplotype frequencies. Since mtDNA represents only maternal inheritance patterns, the present study used bi-parentally inherited microsatellite markers (n=13) to measure differentiation between populations as well as to compare levels of nuclear genetic diversity retained in each. Mean levels of genetic diversity, as measured by the microsatellites, were similar between the eastern and western populations, indicating that the western population has retained relatively high levels of nuclear genetic diversity despite its small size. Comparison of microsatellite allele frequencies confirmed that eastern and western populations are genetically distinct. Although highly statistically significant, the level of differentiation between the two populations is relatively low, and sex-specific analyses suggest that some amount of male-biased dispersal may occur between populations. While these results suggest some movements between the eastern and western populations may take place, the maintenance of genetic differences between the two populations supports their recognition as separate eastern and western populations. Future efforts should focus on elucidating the nature and extent of any dispersal which is occurring in order to better understand factors potentially influencing the recovery of the small western population
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DO NOT CITE WITHOUT AUTHOR PERMISSION SC/60/BRG16 Seasonal and annual variation in body condition of western gray whales off northeastern Sakhalin Island, Russia
2014Co-Authors: Robert L. BrownellAbstract:The western gray whale population (Eschrichtius robustus) is critically endangered and its potential for recovery is uncertain. Along with other natural and anthropogenic threats, western gray whales are susceptible to nutritional stress, known from regular observations of individual whales in compromised body condition. Thus, the ability to visually quantify the relative body condition of free-ranging western gray whales and evaluate how this condition varies seasonally and annually is needed. A photo-identification study of western gray whales on their feeding ground off the northeastern coast of Sakhalin Island, Russia, produced a large dataset of digital, film, and video images of 150 identified individuals from 1994 to 2005. These images were utilized to visually assess the body condition (i.e., good, fair, poor) of western gray whales by evaluating the relative amount of subcutaneous fat in three body regions presumed to reflect reductions in body condition. Multinomial logistic regression for ordinal responses was used to evaluate the effects of year, month, whale class, and sex on the body condition of western gray whales. Although the correlation between observations of individual whales has not yet been accounted for, significant findings of the analysis indicate that: 1) the body condition of whales varied annually and seasonally; 2) the body condition of whales improved as each feeding season progressed; and 3) lactatin
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population abundance and growth rate of western gray whales Eschrichtius robustus
Endangered Species Research, 2008Co-Authors: Amanda L Bradford, David W Weller, Paul R Wade, Alexander M Burdin, Robert L. BrownellAbstract:The western population of gray whales Eschrichtius robustus is one of the most endan- gered whale populations in the world. Recent studies of this population off the northeastern coast of Sakhalin Island, Russia, have produced a photographic dataset that was utilized for the first mark- recapture assessment of western gray whale abundance. Given encounter histories of 129 individu- ally identified whales spanning 25 monthly capture occasions from 1997 to 2003, a closed capture estimator was employed to estimate the number of individuals using the study area in each year. Temporary emigration probabilities were then applied to the closed capture estimates to enumerate the total population size of whales off northeastern Sakhalin Island. Total abundances from 1997 to 2003 were estimated as 64 ± 5.1 (SE), 55 to 75 (95% CI); 75 ± 4.9, 66 to 85; 86 ± 3.1, 80 to 93; 77 ± 4.7, 68 to 87; 91 ± 3.4, 84 to 98; 98 ± 4.1, 90 to 106; and 99 ± 4.9, 90 to 109, respectively. These abundance estimates, particularly the last values in the series, most likely approximate the size of the entire west- ern gray whale population. For comparison to the trend in the abundance estimates, life history data were used to estimate the growth rate of the population. Depending on the range of potential fecundity values incorporated, the resulting growth rate estimates indicate an annual population increase that is between 2.5 and 3.2%. The extremely small population size and slow rate of increase documented here further highlight concern about the viability of this critically endangered population.
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Population assessment of western gray whales in 2006. Paper SC/59/BRG41 presented to the International Whaling Commission
2007Co-Authors: Justin Cooke, David W Weller, Justin G. Cooke, A L. Bradford, Er M. Burdin, Robert L. BrownellAbstract:A population assessment of the western gray whale (Eschrichtius robustus) was conducted using photo-identification data collected off Sakhalin Island under the joint Russia-U.S. programme from 1994 to 2006. This is an update of the assessments by Reeves et al (2005) and Cooke et al. (2006) which used data up to 2003 and 2005 respectively, fitted to the same, individually-based population model. New median estimates of key population parameters (with 90 % Bayesian confidence intervals) are 0.982 (0.972- 0.991) for the non-calf annual survival rate; 0.76 (0.66- 0.85) for the survival rate from calf to yearling; 2.9 % per annum (1.9% – 4.0%) for the average annual rate of population increase over 1994-2006; 0.45 (0.37- 0.52) for the female sex ratio and 121 whales (112- 130) for the 1+ (non-calf) population size in 2007. The updated assessment is more optimistic than the Reeves et al (2005) mainly because of the reduced calving intervals observed in recent years, implying a higher reproductive rate. The modal calving interval has shortened from 3 years up to 2002 to 2 years post-2002. This is consistent with reduced disturbance from industrial activity during 2002-04. Forward projections of the population model to 2050, assuming no additional mortality or disturbance to reproduction, indicate a high probability (>99%) of population increase. Four whales (all female) have bee
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Baleen Whales: Conservation Issues and The Status Of The Most Endangered Populations
Mammal Review, 1999Co-Authors: Phillip J. Clapham, Sharon B. Young, Robert L. BrownellAbstract:Most species of baleen whales were subject to intensive overexploitation by commercial whaling in this and previous centuries, and many populations were reduced to small fractions of their original sizes. Here, we review the status of baleen whale stocks, with an emphasis on those that are known or thought to be critically endangered. Current data suggest that, of the various threats potentially affecting baleen whales, only entanglement in fishing gear and ship strikes may be significant at the population level, and then only in those populations which are already at critically low abundance. The impact of some problems (vessel harassment, and commercial or aboriginal whaling) is at present probably minor. For others (contaminants, habitat degradation, disease), existing data either indicate no immediate cause for concern, or are insufficient to permit an assessment. While the prospect for many baleen whales appears good, there are notable exceptions; populations that are of greatest concern are those suffering from low abundance and associated problems, including (in some cases) anthropogenic mortality. These include: all Northern Right Whales Eubalaena glacialis, Bowhead Whales Balaena mysticetus of the Okhotsk Sea and various eastern Arctic populations, western Gray Whales Eschrichtius robustus, and probably many Blue Whale Balaenoptera musculus populations. We review the status of these populations and, where known, the issues potentially affecting their recovery. Although Humpback Whales Megaptera novaeangliae and Southern Right Whales Eubalaena australis were also heavily exploited by whaling, existing data indicate strong recovery in most studied populations of these species.
Collareta Alberto - One of the best experts on this subject based on the ideXlab platform.
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A PLIOCENE GRAY WHALE (Eschrichtius SP.) FROM THE EASTERN NORTH ATLANTIC
Università degli Studi di Milano, 2020Co-Authors: Tsai Cheng-hsiu, Collareta Alberto, Bosselaers MarkAbstract:The gray whale Eschrichtius robustus, the only living member of the eschrichtiid lineage, currently inhabits only the North Pacific. Interestingly, however, the holotypes of both E. robustus and the late Miocene ArchaEschrichtius ruggieroi (the oldest known eschrichtiid species) come from the North Atlantic and the Mediterranean, respectively. Here we describe a partial mysticete mandible from the Pliocene (3.71–2.76 Ma) of Belgium (Eastern North Atlantic). This new fossil displays a combination of morphological features that makes it nearly identical to modern E. robustus. Nevertheless, given its incomplete nature, the studied specimen is here identified in open nomenclature as belonging to Eschrichtius sp. The recognition of such an early record of Eschrichtius in the North Atlantic suggests that this genus developed a circum-Northern Hemisphere distribution not later than in Pliocene times, thus complicating our understanding of its origin, evolutionary history, and palaeobiogeographic patterns
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The whale barnacle Cryptolepas rhachianecti (Cirripedia: Coronulidae), a phoront of the grey whale Eschrichtius robustus (Cetacea: Eschrichtiidae), from a sandy beach in The Netherlands
2016Co-Authors: Bosselaers Mark, Collareta AlbertoAbstract:Bosselaers, Mark, Collareta, Alberto (2016): The whale barnacle Cryptolepas rhachianecti (Cirripedia: Coronulidae), a phoront of the grey whale Eschrichtius robustus (Cetacea: Eschrichtiidae), from a sandy beach in The Netherlands. Zootaxa 4154 (3): 331-338, DOI: http://doi.org/10.11646/zootaxa.4154.3.
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The whale barnacle Cryptolepas rhachianecti (Cirripedia: Coronulidae), a phoront of the grey whale Eschrichtius robustus (Cetacea: Eschrichtiidae), from a sandy beach in The Netherlands
'Magnolia Press', 2016Co-Authors: Bosselaers Mark, Collareta AlbertoAbstract:An isolated compartment of a whale barnacle is herein described from Recent beach deposits in Zoutelande (Walcheren, The Netherlands). This specimen is identified as belonging to the extant coronulid species Cryptolepas rhachianecti, currently known as an epizoic symbiont of the grey whale Eschrichtius robustus. This find represents the first occurrence of C. rhachianecti outside the North Pacific, and the first one as a (sub) fossil. In view of the fact that E. robustus, which is currently confined to the North Pacific, is known as a subfossil from the northeastern Atlantic between late Late Pleistocene (c. 45,000 years ago) and historical (c. 1700 AD) times, we propose a similar (late Quaternary) age for the isolated compartment. The find indicates that the extinct late Quaternary northeastern Atlantic population of E. robustus was infected by Cryptolepas rhachianecti. Our find is, therefore, compatible with the hypothesis of an ancient grey whale migration route running between the subtropical/temperate waters of the northeast Atlantic (or Mediterranean Basin), and the cold waters of the Baltic Sea (or southern Arctic Ocean), through the southern North Sea. Finally, we discuss the systematic placement of the fossil barnacle species Cryptolepas murata and propose the possibility of its removal from the genus Cryptolepas pending further investigations
Brownell, Robert L. - One of the best experts on this subject based on the ideXlab platform.
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Genetic Differentiation Between Western and Eastern (\u3ci\u3eEschrichtius robustus\u3c/i\u3e) Gray Whale Populations Using Microsatellite Markers
DigitalCommons@University of Nebraska - Lincoln, 2010Co-Authors: Lang, Aimée R., Burdin, Alexander M., Weller, David W., Leduc, Richard G., Brownell, Robert L.Abstract:Within the North Pacific, gray whales (Eschrichtius robustus) are recognized as distinct eastern and western populations. Although both populations were severely reduced by whaling, the eastern population is generally considered to have recovered while the western population has remained highly depleted. Previous studies have documented genetic differentiation between the two populations on the basis of mtDNA haplotype frequencies. Since mtDNA represents only maternal inheritance patterns, the present study used bi-parentally inherited microsatellite markers (n=13) to measure differentiation between populations as well as to compare levels of nuclear genetic diversity retained in each. Mean levels of genetic diversity, as measured by the microsatellites, were similar between the eastern and western populations, indicating that the western population has retained relatively high levels of nuclear genetic diversity despite its small size. Comparison of microsatellite allele frequencies confirmed that eastern and western populations are genetically distinct. Although highly statistically significant, the level of differentiation between the two populations is relatively low, and sex-specific analyses suggest that some amount of male-biased dispersal may occur between populations. While these results suggest some movements between the eastern and western populations may take place, the maintenance of genetic differences between the two populations supports their recognition as separate eastern and western populations. Future efforts should focus on elucidating the nature and extent of any dispersal which is occurring in order to better understand factors potentially influencing the recovery of the small western population
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Status of western gray whales off northeastern Sakhalin Island, Russia, in 2008
DigitalCommons@University of Nebraska - Lincoln, 2009Co-Authors: Burdin, Alexander M., Tsidulko, Grigory A., Sidorenko Maxim, Bradford, Amanda L., Weller, David W., Brownell, Robert L.Abstract:A collaborative Russia-U.S. research program on western gray whales (Eschrichtius robustus) summering off northeastern Sakhalin Island, Russia, has been ongoing since 1995 and has produced important information on the present day conservation status of this critically endangered population. This paper reviews findings from 2008 research activities and combines such with data from previous years, in some cases ranging back to an opportunistic survey in 1994. Photo-identification research conducted off Sakhalin Island in 2008 resulted in the identification of 45 whales, including three calves. No previously unidentified non-calves were observed. When combined with data from 1994-2007, a catalog of 172 photo-identified individuals has been compiled. Not all of these 172 whales can be assumed to be alive, however. One new reproductive female was recorded in 2008, resulting in a minimum of 25 reproductive females being observed since 1995. In addition to a number of biological difficulties that western gray whales are facing, the large-scale offshore oil and gas development programs near their summer feeding ground, as well as fatal net entrapments off Japan during migration, pose significant threats to the future survival of the population
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Anthropogenic Scarring of Western Gray Whales (\u3ci\u3eEschrichtius robustus\u3c/i\u3e)
DigitalCommons@University of Nebraska - Lincoln, 2009Co-Authors: Bradford Amanda, Weller David, Burdin Alexander, Ivaschenko Yulia, Brownell, Robert L.Abstract:Western gray whales (Eschrichtius robustus) are critically endangered and anthropogenic threats, such as entanglement in fishing gear and collisions with vessels, may be acting to limit recovery of the population. Thus, examining the magnitude of such anthropogenic interactions using a scar-based approach is warranted. A multi-year (1995–2005) photo-identification study of western gray whales on their feeding ground off northeastern Sakhalin Island, Russia, has resulted in a large data set of digital and film images of 150 individuals. These images were reviewed and scored for anthropogenic scarring by recording the presence of visible scars resulting from fishing gear entanglement and vessel collisions in 21 defined body regions. In total, 20.0% (n = 30) of whales identified during the study period had detectable anthropogenic scarring, with 18.7% (n = 28) determined to have been previously entangled in fishing gear at least once and 2.0% (n = 3) to have survived at least one vessel collision. These estimates are likely to be conservative given the nature of the photo-identification data set, but indicate that male and female western gray whales are subject to anthropogenic interactions. Future studies designed to systematically estimate the frequency and rates of anthropogenic events are needed and would have direct conservation and management implications
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Survival Estimates of Western Gray Whales \u3ci\u3eEschrichtius robustus\u3c/i\u3e Incorporating Individual Heterogeneity and Temporary Emigration
DigitalCommons@University of Nebraska - Lincoln, 2006Co-Authors: Bradford Amanda, Wade, Paul R., Weller David, Burdin, Alexander M., Ivashchenko Yulia, Tsidulko, Grigory A., Vanblaricom, Glenn R., Brownell, Robert L.Abstract:Gray whales Eschrichtius robustus exist as a 2 geographically and genetically distinct populations in the eastern and western North Pacific. Subjected to intensive commercial whaling during the 19th and 20th centuries, the western population presently numbers approximately 100 individuals and is regarded as one of the most endangered baleen whale populations in the world
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The western gray whale: a review of past exploitation, current status and potential threats
DigitalCommons@University of Nebraska - Lincoln, 2002Co-Authors: Weller David, Burdin Alexander, Wursig Bernd, Taylor Barbara, Brownell, Robert L.Abstract:Gray whales (Eschrichtius robustus) occur along the eastern and western coastlines of the North Pacific as two geographically isolated populations and have traditionally been divided into the eastern (California-Chukchi) and western (Korean-Okhotsk) populations. Recent molecular comparisons confirm, based on differences in haplotypic frequencies, that these populations are genetically separated at the population-level. Both populations were commercially hunted, but only the eastern gray whale has returned to near pre-exploitation numbers. In contrast, the western population remains highly depleted, shows no apparent signs of recovery and its future survival remains uncertain. Research off Sakhalin Island, Russia between 1995 and 1999 has produced important new information on the present day conservation status of western gray whales and provided the basis for the World Conservation Union (IUCN) to list the population as \u27Critically Endangered in 2000. The information presented here, in combination with potential impacts from anthropogenic threats throughout the range of this population, raises strong concerns about the recovery and continued survival of the western gray whale
Bosselaers Mark - One of the best experts on this subject based on the ideXlab platform.
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A PLIOCENE GRAY WHALE (Eschrichtius SP.) FROM THE EASTERN NORTH ATLANTIC
Università degli Studi di Milano, 2020Co-Authors: Tsai Cheng-hsiu, Collareta Alberto, Bosselaers MarkAbstract:The gray whale Eschrichtius robustus, the only living member of the eschrichtiid lineage, currently inhabits only the North Pacific. Interestingly, however, the holotypes of both E. robustus and the late Miocene ArchaEschrichtius ruggieroi (the oldest known eschrichtiid species) come from the North Atlantic and the Mediterranean, respectively. Here we describe a partial mysticete mandible from the Pliocene (3.71–2.76 Ma) of Belgium (Eastern North Atlantic). This new fossil displays a combination of morphological features that makes it nearly identical to modern E. robustus. Nevertheless, given its incomplete nature, the studied specimen is here identified in open nomenclature as belonging to Eschrichtius sp. The recognition of such an early record of Eschrichtius in the North Atlantic suggests that this genus developed a circum-Northern Hemisphere distribution not later than in Pliocene times, thus complicating our understanding of its origin, evolutionary history, and palaeobiogeographic patterns
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The whale barnacle Cryptolepas rhachianecti (Cirripedia: Coronulidae), a phoront of the grey whale Eschrichtius robustus (Cetacea: Eschrichtiidae), from a sandy beach in The Netherlands
2016Co-Authors: Bosselaers Mark, Collareta AlbertoAbstract:Bosselaers, Mark, Collareta, Alberto (2016): The whale barnacle Cryptolepas rhachianecti (Cirripedia: Coronulidae), a phoront of the grey whale Eschrichtius robustus (Cetacea: Eschrichtiidae), from a sandy beach in The Netherlands. Zootaxa 4154 (3): 331-338, DOI: http://doi.org/10.11646/zootaxa.4154.3.
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The whale barnacle Cryptolepas rhachianecti (Cirripedia: Coronulidae), a phoront of the grey whale Eschrichtius robustus (Cetacea: Eschrichtiidae), from a sandy beach in The Netherlands
'Magnolia Press', 2016Co-Authors: Bosselaers Mark, Collareta AlbertoAbstract:An isolated compartment of a whale barnacle is herein described from Recent beach deposits in Zoutelande (Walcheren, The Netherlands). This specimen is identified as belonging to the extant coronulid species Cryptolepas rhachianecti, currently known as an epizoic symbiont of the grey whale Eschrichtius robustus. This find represents the first occurrence of C. rhachianecti outside the North Pacific, and the first one as a (sub) fossil. In view of the fact that E. robustus, which is currently confined to the North Pacific, is known as a subfossil from the northeastern Atlantic between late Late Pleistocene (c. 45,000 years ago) and historical (c. 1700 AD) times, we propose a similar (late Quaternary) age for the isolated compartment. The find indicates that the extinct late Quaternary northeastern Atlantic population of E. robustus was infected by Cryptolepas rhachianecti. Our find is, therefore, compatible with the hypothesis of an ancient grey whale migration route running between the subtropical/temperate waters of the northeast Atlantic (or Mediterranean Basin), and the cold waters of the Baltic Sea (or southern Arctic Ocean), through the southern North Sea. Finally, we discuss the systematic placement of the fossil barnacle species Cryptolepas murata and propose the possibility of its removal from the genus Cryptolepas pending further investigations
Sue E. Moore - One of the best experts on this subject based on the ideXlab platform.
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Killer Whales (Orcinus orca) Chasing Gray Whales (Eschrichtius robustus)
2014Co-Authors: In The Northern Bering Sea, Donald K. Ljungblad, Sue E. MooreAbstract:ABSTRACT. Sixteen killer whales ( O r c i w o m) were observed for 90 minucs as they approached and then chased gray whales (fichrichtiw robustus) in the Bering Sea north of St. Lawrence Island, Alaska. The killer whales swam in four discrete lines that blew synchronously as they a p proached an area in which gray whales were feeding. Once in the gray whales ' feeding area, the killer whales broke into small groups and dispersed. The gray whales, which had been dispersed while feeding, formed groups of three to six and swam away from the killer whales, except for one in-dividual. That whale was pursued by four killer whales swimming nearly abreast in a loose crescent formation with about 300 m between individuals. Although a sonobuoy was deployed throughout the observation period, no sounds were recorded from either species. The absence of whale sounds raises questions about how the whales detected one another and communicated between nearby conspecifics. Key words: killer whale (Orcinus orca), gray whale (Eschrichtius robustus), Bering Sea, predator/py, acoustics &UMfi. Seize tpaulards ( O r c i w orca) ont t t t observts pendant 90 minutes en train d'approcher et ensuite de chasser des baleines grises de Californie (Eschrichrius robwrus) dans la mer de Bering au nord de I'ile St. Lawrence, en Alaska. A I'approche de I ' d d'alimentation des baleines grises, les tpaulards nageaient en quatre lignes discdtes soufflant leurs colonnes d'eau de facon synchroni&. Une fois arrivts, les 6paulards se divisbrent en petits groupes et s'bparpillbrent. Les baleines grises, disper&s lors de la prise de nourriture, f o d r e n t des groupes de trois h six animaux et s'tloigdrent B la Rage des tpaulards, sauf un seul individu. Celuici fut pwrsuivi par quatre 6paulards nageant presque cBte h c6te dans une formation peu serf & en forme de croissant laissant quelque 3Ml m entre les individus. Bien qu'une radio-balise acoustique eut W dtployb durant la durte entikre de la Nriode &observation, aucun son n'a kt6 enregist & de la part des deux espkces. L'absence des sons de baleines laisse
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A note on observations of gray whales in the southern Chukchi and northern Bering Seas, August-November, 1980-89
2014Co-Authors: Janet T. Clarke, Sue E. MooreAbstract:A total of 176 sightings of 488 gray whales (Eschrichtius robustus) were made during 85.6 hours of aerial surveys in the southern Chukchi Sea and northern Bering Sea, east of the International Date Line, from August to early November 1980-1989. Surveys were flown infrequently and effort varied considerably between years and geographic areas. Gray whales were sighted in all areas where surveys were flown, with the exceptions of Kotzebue Sound and Norton Sound. Abundance indices of whales per unit effort (WPUE) in the northern Bering Sea were higher than those in the southern Chukchi Sea during every month except September, when survey coverage was inadequate for abundance calculations, indicating comparatively higher overall use of that area or suggesting the onset of the southbound migration. Most gray whales were feeding (57%, n = 276). Incidental sightings of gray whales observed in and near the study area by other researchers were reviewed to better assess gray whale activity and migration patterns
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marine mammals as ecosystem sentinels
Journal of Mammalogy, 2008Co-Authors: Sue E. MooreAbstract:The earth’s climate is changing, possibly at an unprecedented rate. Overall, the planet is warming, sea ice and glaciers are in retreat, sea level is rising, and pollutants are accumulating in the environment and within organisms. These clear physical changes undoubtedly affect marine ecosystems. Species dependent on sea ice, such as the polar bear (Ursus maritimus) and the ringed seal (Phoca hispida), provide the clearest examples of sensitivity to climate change. Responses of cetaceans to climate change are more difficult to discern, but in the eastern North Pacific evidence is emerging that gray whales (Eschrichtius robustus) are delaying their southbound migration, expanding their feeding range along the migration route and northward to Arctic waters, and even remaining in polar waters over winter—all indications that North Pacific and Arctic ecosystems are in transition. To use marine mammals as sentinels of ecosystem change, we must expand our existing research strategies to encompass the decadal and ocean-basin temporal and spatial scales consistent with their natural histories.
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gray whale distribution relative to forage habitat in the northern bering sea current conditions and retrospective summary
Canadian Journal of Zoology, 2003Co-Authors: Sue E. Moore, Jacqueline M Grebmeier, Jeremy R DaviesAbstract:Hundreds of gray whales (Eschrichtius robustus) stranded dead along beaches from Mexico to Alaska in 1999 and 2000. The cause of the mortalities remains unknown, but starvation resulting from a red...
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cetacean habitat selection in the alaskan arctic during summer and autumn
Arctic, 2000Co-Authors: Sue E. Moore, Douglas P Demaster, Paul K DaytonAbstract:Ten years (1982-91) of sighting data from aerial surveys offshore of northern Alaska were analyzed to investigate seasonal variability in cetacean habitat selection. Distinct habitats were described for bowhead whales ( Balaena mysticetus ), white whales ( Delphinapterus leucas ), and gray whales ( Eschrichtius robustus ) on the basis of habitat selection ratios calculated for bathymetric and ice cover regimes. In summer, bowheads selected continental slope waters and moderate ice conditions; white whales selected slope and basin waters and moderate to heavy ice conditions; and gray whales selected coastal/shoal waters and open water. In autumn, bowheads selected inner shelf waters and light ice conditions; white whales selected outer shelf and slope waters and moderate to heavy ice; and gray whales selected coastal and shoal/trough habitats in light ice and open water. Habitat differences among species were significant in both seasons (ANOVA F > 28, p 0.35). White whale depth habitat was significantly different between seasons ( p < 0.00002), but ice cover habitat was not ( p < 0.08).