Discovery of Northern Fur Seals (Callorhinus ursinus) Breeding on Bogoslof Island Southeastern Bering Sea

ARCTIC ◽  
1981 ◽  
Vol 34 (4) ◽  
Author(s):  
Denby S. Lloyd ◽  
C. Peter McRoy ◽  
Robert H. Day
Keyword(s):  
Bering Sea ◽  
Callorhinus Ursinus ◽  
Fur Seals ◽  
Northern Fur Seals

Net energy gained by northern fur seals (Callorhinus ursinus) is impacted more by diet quality than by diet diversity

2016 ◽  
Vol 94 (2) ◽  
pp. 123-135 ◽  
Author(s):  
Mariana Diaz Gomez ◽  
David A.S. Rosen ◽  
Andrew W. Trites
Keyword(s):  
Energy Loss ◽  
Diet Quality ◽  
Bering Sea ◽  
Callorhinus Ursinus ◽  
Net Energy ◽  
Diet Diversity ◽  
Fur Seals ◽  
Heat Increment Of Feeding ◽  
Northern Fur Seals ◽  
Heat Increment

Understanding whether northern fur seals (Callorhinus ursinus (L., 1758)) are negatively affected by changes in prey quality or diversity could provide insights into their on-going population decline in the central Bering Sea. We investigated how six captive female fur seals assimilated energy from eight different diets consisting of four prey species (walleye pollock (Gadus chalcogrammus Pallas, 1814, formerly Theragra chalcogrammus (Pallas, 1814)), Pacific herring (Clupea pallasii Valenciennes in Cuvier and Valenciennes, 1847), capelin (Mallotus villosus (Müller, 1776)), and magister armhook squid (Berryteuthis magister (Berry, 1913))) fed alone or in combination. Net energy was quantified by measuring fecal energy loss, urinary energy loss, and heat increment of feeding. Digestible energy (95.9%–96.7%) was high (reflecting low fecal energy loss) and was negatively affected by ingested mass and dietary protein content. Urinary energy loss (9.3%–26.7%) increased significantly for high-protein diets. Heat increment of feeding (4.3%–12.4%) was significantly lower for high-lipid diets. Overall, net energy gain (57.9%–83.0%) was affected by lipid content and varied significantly across diets. Mixed-species diets did not provide any energetic benefit over single-species diets. Our study demonstrates that diet quality was more important in terms of energy gain than diet diversity. These findings suggest that fur seals consuming low-quality prey in the Bering Sea would be more challenged to obtain sufficient energy to satisfy energetic and metabolic demands, independent of high prey abundance.

Inter-island variation in the diet of female northern fur seals (Callorhinus ursinus) in the Bering Sea

2009 ◽  
Vol 242 (3) ◽  
pp. 435-451 ◽  
Author(s):  
G. A. Antonelis ◽  
E. H. Sinclair ◽  
R. R. Ream ◽  
B. W. Robson
Keyword(s):  
Bering Sea ◽  
Callorhinus Ursinus ◽  
Fur Seals ◽  
Northern Fur Seals ◽  
The Bering Sea

Estimation of Sexual Maturity Based on Morphometrics of Genital Organs in Male Northern Fur Seals, Callorhinus ursinus

Mammal Study ◽  
2020 ◽  
Vol 46 (1) ◽  
Author(s):  
Yukino Hirakawa ◽  
Takanori Horimoto ◽  
Ippei Suzuki ◽  
Yoko Mitani
Keyword(s):  
Sexual Maturity ◽  
Callorhinus Ursinus ◽  
Fur Seals ◽  
Northern Fur Seals

NATURALLY-OCCURRING LEPTOSPIROSIS IN NORTHERN FUR SEALS (Callorhinus ursinus)

1977 ◽  
Vol 13 (2) ◽  
pp. 144-148 ◽  
Author(s):  
ALVIN W. SMITH ◽  
RICHARD J. BROWN ◽  
DOUGLAS E. SKILLING ◽  
H. L. BRAY ◽  
MARK C. KEYES
Keyword(s):  
Callorhinus Ursinus ◽  
Naturally Occurring ◽  
Fur Seals ◽  
Northern Fur Seals

Estimating the Juvenile Survival Rate of Male Northern Fur Seals (Callorhinus ursinus)

1989 ◽  
Vol 46 (8) ◽  
pp. 1428-1436 ◽  
Author(s):  
Andrew W. Trites
Keyword(s):  
Survival Rate ◽  
Juvenile Survival ◽  
Callorhinus Ursinus ◽  
Strongly Correlated ◽  
Fur Seals ◽  
Commercial Harvest ◽  
Northern Fur Seals ◽  
Back Calculation ◽  
Number Of Males ◽  
Insight Into

Three methods for estimating the survival rate of juvenile northern fur seals (Callorhinus ursinus) are developed from the earlier works of Chapman, Smith and Polacheck and Lander. Each of the methods I propose divides the estimated number of males alive at 2 yr of age by the estimated number of pups born in their year class. The number of surviving juveniles are reconstructed by back calculation using the number of males killed during the commercial harvest and the subsequent counts of bulls. The three methods differ in their assumptions concerning subadult survival and escapement from the harvest, although all produce similar estimates when applied to the St. Paul Island fur seals. These new estimates of juvenile survival (1950–80) are strongly correlated with the ratio of cohort kill to pup production and with estimates from the currently-used Lander procedure. This is because the harvest morality of males is large compared with natural morality. The new methods perform acceptably over a wider class of data than Lander's. Their greatest advantage over current procedures is that they provide a better insight into the reliability of the survival estimates they produce.

Digeneans of northern fur seals Callorhinus ursinus (Pinnipedia: Otariidae) from five subpopulations on St. Paul Island, Alaska

2018 ◽  
Vol 117 (4) ◽  
pp. 1079-1086 ◽  
Author(s):  
T. A. Kuzmina ◽  
V. V. Tkach ◽  
T. R. Spraker ◽  
E. T. Lyons ◽  
O. Kudlai
Keyword(s):  
Callorhinus Ursinus ◽  
Fur Seals ◽  
Northern Fur Seals
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