Stock discrimination of Atlantic walrus (Odobenus rosmarus rosmarus) in the eastern Canadian Arctic using lead isotope and element signatures in teeth

1999 ◽  
Vol 56 (1) ◽  
pp. 105-112 ◽  
Author(s):  
P M Outridge ◽  
R EA Stewart
Keyword(s):  
Canadian Arctic ◽  
Isotope Ratios ◽  
High Arctic ◽  
Trace Element Composition ◽  
Pb Isotope ◽  
Foxe Basin ◽  
Stock Discrimination ◽  
Odobenus Rosmarus ◽  
Odobenus Rosmarus Rosmarus ◽  
Atlantic Walrus

Atlantic walrus (Odobenus rosmarus rosmarus) harvested from three regions of the Canadian Arctic, and by different communities within two of those regions, were distinguished using the stable Pb isotope or trace element composition of their tooth cementum. Walrus from Foxe Basin (Igloolik, Hall Beach), the High Arctic (Grise Fiord, Resolute Bay), and eastern Hudson Bay (Akulivik, Inukjuak) were each characterized by specific combinations of Pb isotope ratios and Co concentrations, and we conclude that they represent different regional stocks. Walrus landed at Akulivik and Inukjuak were further discriminated by significant differences in 208Pb/207Pb, even though the communities are only 250 km apart. There was more overlap between walrus from Igloolik and Hall Beach, which are 80 km apart, but significant differences between sites in Pb isotope ratios and in concentrations of V, Zn, and Mo suggested that more than one Foxe Basin stock was being harvested. Particularly at Hall Beach, the herds contained a few individuals with isotope ratios significantly different from the rest of the population. These "outliers" may represent either immigrants from other geological provinces or animals caught in other areas. Further investigation of the outliers could provide information regarding hunting patterns, walrus home ranges, and the rates and demographics of interstock migrations.

Summer foods of Atlantic walrus, Odobenus rosmarus rosmarus, in northern Foxe Basin, Northwest Territories

1997 ◽  
Vol 75 (7) ◽  
pp. 1166-1175 ◽  
Author(s):  
K. I. Fisher ◽  
R. E. A. Stewart
Keyword(s):  
Benthic Invertebrates ◽  
Stomach Contents ◽  
Male And Female ◽  
Foxe Basin ◽  
Important Prey ◽  
Odobenus Rosmarus ◽  
Serripes Groenlandicus ◽  
Gross Energy ◽  
Odobenus Rosmarus Rosmarus ◽  
Atlantic Walrus

Stomach contents of Atlantic walrus, Odobenus rosmarus rosmarus, taken by Inuit hunters in northern Foxe Basin in July 1987 and 1988 (n = 105) and September 1988 (n = 2) were examined. In July, 20 of 94 stomachs from immature and adult walrus contained > 5 g of food representing 17 prey taxa, including bivalves, gastropods, holothurians, polychaetes, and brachiopods. The bivalve Mya truncata contributed 81.4% of the total gross energy in the diet, with the bivalve Hiatella arctica, holothurians, and the polychaete Nereis sp. contributing 7.5, 3.5, and 2.8%, respectively. The diets of male and female walrus were similar except that females received a significantly (P < 0.05) greater percentage of gross energy in their diet from H. arctica than did males. Walrus less than 3 years old (n = 11) consumed mostly milk, although some benthic invertebrates were eaten. Analysis of the contents of two stomachs collected in September suggested that walrus may feed more intensively in the fall. Mya truncata was again the predominant prey, contributing 59.9% of total gross energy, with the bivalve Serripes groenlandicus (37.9%) replacing H. arctica (0.3%) as the second most important prey.

scholarly journals A catch history for Atlantic walruses (Odobenus rosmarus rosmarus) in the eastern Canadian Arctic

2014 ◽  
Vol 9 ◽  
pp. 219 ◽  
Author(s):  
D Bruce Stewart ◽  
Jeff W Higdon ◽  
Randall R Reeves ◽  
Robert EA Stewart
Keyword(s):  
Canadian Arctic ◽  
High Arctic ◽  
Bowhead Whale ◽  
Steady Increase ◽  
Odobenus Rosmarus ◽  
Inuit Population ◽  
Minimum Numbers ◽  
Over Time ◽  
Eastern Canadian Arctic ◽  
Odobenus Rosmarus Rosmarus

Knowledge of changes in abundance of Atlantic walruses (Odobenus rosmarus rosmarus) in Canada is important for assessing their current population status. This catch history collates available data and assesses their value for modelling historical populations to inform population recovery and management. Pre-historical (archaeological), historical (e.g., Hudson Bay Company journals) and modern catch records are reviewed over time by data source (whaler, land-based commercial, subsistence etc.) and biological population or management stock.Direct counts of walruses landed as well as estimates based on hunt products (e.g., hides, ivory) or descriptors (e.g., Peterhead boatloads) support a minimum landed catch of over 41,300 walruses in the eastern Canadian Arctic between 1820 and 2010. Little is known of Inuit catches prior to 1928, despite the importance of walruses to many Inuit groups for subsistence. Commercial hunting from the late 1500s to late 1700s extirpated the Atlantic walrus from Quebec and the Atlantic Provinces, but there was no commercial hunt for the species in the Canadian Arctic until ca. 1885. As the availability of bowhead whale (Balaena mysticetus) declined, whalers increasingly turned to hunting other species, including walruses. Modest numbers (max. 278/yr) were taken from the High Arctic population in the mid-1880s and large catches (up to 1400/yr) were often taken from the Central Arctic population from 1899 -1911, while the Foxe Basin stock (Central Arctic population) and Low Arctic population were largely ignored by commercial hunters. Land-based traders (ca. 1895-1928) continued the commercial hunt until regulatory changes in 1928 reserved walruses for Inuit use. Since 1950, reported walrus catches have been declining despite a steady increase in the Inuit population. Effort data are needed to assess whether lower catches stem from declining hunter effort or decreased walrus abundance. The recent take of walruses by sport hunting has been small (n=141, 1995-2010), sporadic and local.These landed catch estimates indicate the minimum numbers of walruses removed but do not account for under-reporting or lost animals that were killed but were not secured. Unreported and lost animals may represent a significant fraction of the total removals and must be considered in any modelling exercise. The sources, quality and completeness of the catch data vary widely over time and space and between the different hunt types. This variability confounds interpretation and contributes to the uncertainty that needs to be incorporated into any modelling. The data on Inuit subsistence catches before ca. 1928 are particularly fragmentary and uncertain. 

A TRITIATED WATER EXPERIMENT ON A MALE ATLANTIC WALRUS (ODOBENUS ROSMARUS ROSMARUS)

1992 ◽  
Vol 8 (4) ◽  
pp. 418-420 ◽  
Author(s):  
Christian Lydersen ◽  
David Griffiths ◽  
Ian Gjertz ◽  
Oystein Wiig
Keyword(s):  
Tritiated Water ◽  
Odobenus Rosmarus ◽  
Odobenus Rosmarus Rosmarus ◽  
Atlantic Walrus

Historical sex-specific distribution of Atlantic walrus (Odobenus rosmarus rosmarus) in Svalbard assessed by mandible measurements

Polar Biology ◽  
2007 ◽  
Vol 31 (1) ◽  
pp. 69-75 ◽  
Author(s):  
Øystein Wiig ◽  
Erik W. Born ◽  
Ian Gjertz ◽  
Christian Lydersen ◽  
Robert E. A. Stewart
Keyword(s):  
Odobenus Rosmarus ◽  
Specific Distribution ◽  
Odobenus Rosmarus Rosmarus ◽  
Atlantic Walrus

The breeding behavior of Atlantic walruses, Odobenus rosmarus rosmarus, in the Canadian High Arctic

1996 ◽  
Vol 74 (5) ◽  
pp. 897-911 ◽  
Author(s):  
B. Sjare ◽  
I. Stirling
Keyword(s):  
Mating System ◽  
Open Water ◽  
High Arctic ◽  
Easy Access ◽  
Breeding Behavior ◽  
Canadian High Arctic ◽  
Odobenus Rosmarus ◽  
Ice Conditions ◽  
Female Defense Polygyny ◽  
Odobenus Rosmarus Rosmarus

The breeding behavior of Atlantic walruses, Odobenus rosmarus rosmarus, overwintering at the Dundas Island polynya (76 °09′N, 94 °52′W) in the Canadian High Arctic was studied from 1981 to 1990. Approximately 25–65 walruses frequented the polynya area each winter; their distribution was determined by sea-ice features (e.g., thin annual ice, cracks) that ensured easy access to open water. The mating system of walruses breeding in the area is best described as female-defense polygyny. A large mature male had exclusive access to a herd of walruses containing several females for 1–5 days at a time. Although there were numerous males in the polynya capable of attending a herd during the breeding season, one or two males spent significantly more time with a herd. It was not evident that female preference was important in determining which male became the attending male. When attending a herd, a male continuously repeated a complex, stereotyped underwater song. Other sexually mature males in the area behaved as silent herd members, vocal satellite males, or, in some cases, both. The small number of walruses at the polynya, the sedentary nature of the population due to ice conditions, and the inherent gregariousness of female walruses appear to be important factors influencing the evolution of social behavior and the mating system in walruses

Comparison of mandibular with cemental growth-layer counts for ageing Atlantic walrus (Odobenus rosmarus rosmarus)

1993 ◽  
Vol 71 (1) ◽  
pp. 163-167 ◽  
Author(s):  
J. L. Garlich-Miller ◽  
R. E. A. Stewart ◽  
B. E. Stewart ◽  
E. A. Hiltz
Keyword(s):  
Growth Rate ◽  
Growth Layer ◽  
Mandibular Growth ◽  
Odobenus Rosmarus ◽  
Main Factors ◽  
The Relationship ◽  
Odobenus Rosmarus Rosmarus ◽  
Atlantic Walrus ◽  
Age Estimates

The relationship between the numbers of growth layers counted in the mandible and in the cementum of lower canines from 87 walrus (Odobenus rosmarus rosmarus) was examined. A 1:1 correlation between counts of growth layers in the two tissues was found in males ≤ 19 years old and females ≤ 9 years old. No correlation was found in males with ≥ 21 or in females with ≥ 10 cemental growth layers. In physically mature walrus, mandibular layering was unreliable for age analysis. Resorption and a reduced mandibular growth rate appear to be the main factors limiting mandibular age estimates in mature walrus.

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