Acoustic monitoring of northern fur seals in the Bering Sea

2004 ◽  
Vol 116 (4) ◽  
pp. 2555-2555 ◽  
Author(s):  
Stephen J. Insley ◽  
Bruce W. Robson ◽  
William C. Burgess
Keyword(s):  
Bering Sea ◽  
Acoustic Monitoring ◽  
Fur Seals ◽  
Northern Fur Seals ◽  
The Bering Sea

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

scholarly journals Extreme weather events influence dispersal of naive northern fur seals

2009 ◽  
Vol 5 (2) ◽  
pp. 252-257 ◽  
Author(s):  
Mary-Anne Lea ◽  
Devin Johnson ◽  
Rolf Ream ◽  
Jeremy Sterling ◽  
Sharon Melin ◽  
...  
Keyword(s):  
Bering Sea ◽  
Marine Mammals ◽  
Habitat Choice ◽  
Climatic Conditions ◽  
Extreme Weather Events ◽  
First Year ◽  
Atmospheric Conditions ◽  
Fur Seals ◽  
San Miguel Island ◽  
The Bering Sea

Since 1975, northern fur seal ( Callorhinus ursinus ) numbers at the Pribilof Islands (PI) in the Bering Sea have declined rapidly for unknown reasons. Migratory dispersal and habitat choice may affect first-year survivorship, thereby contributing to this decline. We compared migratory behaviour of 166 naive pups during 2 years from islands with disparate population trends (increasing: Bogoslof and San Miguel Islands; declining: PI), hypothesizing that climatic conditions at weaning may differentially affect dispersal and survival. Atmospheric conditions (Bering Sea) in autumn 2005–2006 were anomalously cold, while 2006–2007 was considerably warmer and less stormy. In 2005, pups departed earlier at all sites, and the majority of PI pups (68–85%) departed within 1 day of Arctic storms and dispersed quickly, travelling southwards through the Aleutian Islands. Tailwinds enabled faster rates of travel than headwinds, a trend not previously shown for marine mammals. Weather effects were less pronounced at Bogoslof Island (approx. 400 km further south), and, at San Miguel Island, (California) departures were more gradual, and only influenced by wind and air pressure in 2005. We suggest that increasingly variable climatic conditions at weaning, particularly timing, frequency and intensity of autumnal storms in the Bering Sea, may alter timing, direction of dispersal and potentially survival of pups.

Newborn northern fur seals (Callorhinus ursinus)--do they suffer from cold?

1979 ◽  
Vol 236 (5) ◽  
pp. R322-R327
Author(s):  
A. S. Blix ◽  
L. K. Miller ◽  
M. C. Keyes ◽  
H. J. Grav ◽  
R. Elsner
Keyword(s):  
Resting Metabolic Rate ◽  
Deep Body Temperature ◽  
Fur Seals ◽  
Rainy Weather ◽  
Northern Fur Seals ◽  
C 50 ◽  
High Level ◽  
July Temperature ◽  
Deep Body ◽  
The Bering Sea

Several hundred thousand northern fur seals (C. ursinus) are born each summer during July at St. Paul Island in the Bering Sea. The weather in the area is usually cold, wet, and windy during the breeding season. At birth the pups are small (5--6 kg) and insulated only by a partly wettable pelt and a 2- to 4-mm layer of blubber. In air, the pups' lower critical temperature appears to be below the 6 degrees C 50-yr record low July temperature for the islands. During rainy weather much of the insulative value of the pelt is lost, and the pups, which already have a high resting metabolic rate of 3.5 W.kg-1, must increase heat production by shivering and/or nonshivering thermogenesis to maintain deep body temperature. The high level of metabolism (up to 18 W.kg-1) is supported by a very rich milk. The pups will, nevertheless, become hypothermic if their insulation is not improved through peripheral vasoconstriction and shedding of water from the pelt by periodic shudder. Even with these protections the newborn and very young pups are brought close to their limit of tolerance during rainy and windy days. Unfit pups are likely to succumb under such circumstances.

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.

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