Comparing total body lipid content of young-of-the-year Steller sea lions among regions of contrasting population trends

2016 ◽  
Vol 32 (4) ◽  
pp. 1200-1218 ◽  
Author(s):  
Lorrie D. Rea ◽  
Brian S. Fadely ◽  
Sean D. Farley ◽  
Julie P. Avery ◽  
Wendy S. Dunlap-Harding ◽  
...  
Keyword(s):  
Lipid Content ◽  
Population Trends ◽  
Body Lipid ◽  
Steller Sea Lions ◽  
Sea Lions ◽  
Young Of The Year ◽  
Total Body

Utilization of stored energy reserves during fasting varies by age and season in Steller sea lions

2007 ◽  
Vol 85 (2) ◽  
pp. 190-200 ◽  
Author(s):  
L.D. Rea ◽  
D.A.S. Rosen ◽  
A.W. Trites
Keyword(s):  
Mass Loss ◽  
Body Mass ◽  
Breeding Season ◽  
Lower Percentage ◽  
Metabolic Adaptation ◽  
Body Lipid ◽  
Steller Sea Lions ◽  
Sea Lions ◽  
Nonbreeding Season ◽  
Total Body

Nine captive Steller sea lions ( Eumetopias jubatus (Schreber, 1776), 1.75–6 years of age) were fasted for 7–14 d to test the effect of short-term fasting on changes in body mass and body condition. Trials were repeated during both the summer breeding season and the nonbreeding season in seven animals to elucidate whether there was a seasonal component to the ability of Steller sea lions to adapt to limited food resources. Mean percent mass loss per day was higher during the breeding season in juveniles (1.8% ± 0.2%·d–1) than in subadults (1.2% ± 0.1%·d–1), but there were no significant age-related differences during the nonbreeding season (juveniles, 1.5% ± 0.3%·d–1; subadults, 1.7% ± 0.3%·d–1). A decrease in the rate of mass loss occurred after the first 3 d of fasting only in subadults during the breeding season. Percent total body lipid ranged from 11% to 28% of total body mass at the initiation of fasting trials. Animals with lower initial percent total body lipid exhibited higher subsequent rates of mass loss and a lower percentage of tissue catabolism derived from lipid reserves. There was no evidence of metabolic adaptation to fasting in juveniles, which suggests that juvenile sea lions would be more negatively impacted by food limitation during the breeding season than would subadults.

Model of spontaneous obesity in aging male Wistar rats

1990 ◽  
Vol 259 (6) ◽  
pp. R1117-R1125 ◽  
Author(s):  
F. D. Newby ◽  
M. DiGirolamo ◽  
G. A. Cotsonis ◽  
M. H. Kutner
Keyword(s):  
Body Weight ◽  
Lipid Content ◽  
Wistar Rats ◽  
Lipid A ◽  
Curvilinear Relationship ◽  
Body Lipid ◽  
Fat Depots ◽  
Male Wistar Rats ◽  
Total Body ◽  
Relationship Of

We analyzed retrospectively data from 148 chow-fed male Wistar rats killed between the age of 6 wk and 2 yr while varying in body weight from 136 to 917 g. The purpose of this study was to clarify the relationship of body weight and body lipid content with the composition and cellularity of the epididymal and retroperitoneal fat depots. A positive linear association was found between body weight and body water or fat-free dry residue, whereas total body lipid exhibited a curvilinear relationship with body weight. The weight of the epididymal pads was linearly related to body weight but not to body lipid. In contrast, retroperitoneal pad weight was exponentially related to body weight and paralleled total body lipid. A strong linear correlation was found between total body lipid and weight (r = 0.959) or depot lipid content (r = 0.967) of the retroperitoneal fat pads. In this rat model of aging and spontaneous obesity, significant regional differences exist in adipose depot composition and cellularity. A practical outcome of this study is a simple and accurate prediction of body lipid content from the gravimetric determination of the retroperitoneal fat depots.

Season variation in nutrient composition of Alaskan walleye pollock

2004 ◽  
Vol 82 (9) ◽  
pp. 1408-1415 ◽  
Author(s):  
David D Kitts ◽  
Minh Dieu Huynh ◽  
Chun Hu ◽  
Andrew W Trites
Keyword(s):  
Lipid Content ◽  
Gonad Development ◽  
Nutrient Content ◽  
Protein Digestibility ◽  
Analysis Data ◽  
Dry Mass ◽  
Walleye Pollock ◽  
Steller Sea Lions ◽  
Crude Lipid ◽  
Sea Lions

A popular hypothesis for the noted steady decline in the population of Steller sea lions, Eumetopias jubatus (Schreber, 1776), in the regions from Prince William Sound through the Aleutian Islands relates to their nutritional status. Sea lion diets appear to have shifted from primarily small schooling fatty fishes to low-fat fish such as walleye pollock, Theragra chalcogramma (Pallas, 1814). We examined the seasonal changes in proximate nutrients of pollock collected in the Bering Sea. Mean energy density (dry mass) of pollock peaked in October then declined and remained low throughout winter. Energy recovery occurred in the summer months with strong recovery observed in female fish caught in July. Contrary to whole fish carcass energy contents, both total protein and moisture contents were at their highest levels in winter (January) when total crude lipid content was at its lowest (p < 0.05). This trend gradually declined to its lowest levels in the fall when lipid content was high. The decline in total lipids during winter seasons appeared to parallel gonad development during the prespawning period. Sex differences in energy densities were not found. Proximate analysis data for moisture, protein, ash, and lipid content also did not show any significant variation between males and females. Protein digestibility of pollock was higher (p < 0.05) in the summer than in the spring, but not different for winter or fall. We concluded that the nutrient content of walleye pollock may have some impact on the Steller sea lions that feed on them, particularly the energetic value that appears to be low during important feeding periods for this marine mammal.

scholarly journals Age Specific Survival Rates of Steller Sea Lions at Rookeries with Divergent Population Trends in the Russian Far East

PLoS ONE ◽  
2015 ◽  
Vol 10 (5) ◽  
pp. e0127292 ◽  
Author(s):  
Alexey V. Altukhov ◽  
Russel D. Andrews ◽  
Donald G. Calkins ◽  
Thomas S. Gelatt ◽  
Eliezer D. Gurarie ◽  
...  
Keyword(s):  
Russian Far East ◽  
Survival Rates ◽  
Far East ◽  
Population Trends ◽  
Steller Sea Lions ◽  
Sea Lions ◽  
The Russian Far East

Foraging behavior of adult female and young-of-the-year Steller sea lions in Alaskan waters

1997 ◽  
Vol 75 (5) ◽  
pp. 776-786 ◽  
Author(s):  
Richard L. Merrick ◽  
Thomas R. Loughlin
Keyword(s):  
Adult Female ◽  
Prey Availability ◽  
Gulf Of Alaska ◽  
First Year ◽  
Home Ranges ◽  
Steller Sea Lions ◽  
Foraging Effort ◽  
Sea Lions ◽  
Adult Females ◽  
Young Of The Year

One explanation for recent declines in the Alaskan Steller sea lion (Eumetopias jubatus) population is that the availability of preferred prey has changed. Part of our evaluation of this hypothesis involved the use of conventional radio and satellite-linked time–depth recorder transmitters to compare summer and winter foraging of adult female and young-of-the-year Steller sea lions in Alaska waters. Foraging effort was not significantly different seasonally for postpartum adult females, though females with dependent young in winter may increase their foraging effort. In winter, all adult females made longer trips over larger home ranges and dove deeper. Young sea lions exerted less foraging effort, had the shallowest and briefest dives, and had home ranges intermediate in size to the two groups of adult females. Their foraging ability appears to develop throughout the first year. We conclude that adult female sea lions can exploit prey throughout the Gulf of Alaska and Bering Sea, and are constrained only by their reproductive status and seasonal changes in prey availability. Young sea lions' diving is more limited because their physiological and behavioral development constrains them from diving like an adult. Perhaps most important, dives remain shallow through the first year. Consequently, young sea lions could be more easily food-limited by changes in prey distribution.

A re-examination of the relationship between Steller sea lion (Eumetopias jubatus) diet and population trend using data from the Aleutian Islands

2019 ◽  
Vol 97 (12) ◽  
pp. 1137-1155 ◽  
Author(s):  
L. Fritz ◽  
B. Brost ◽  
E. Laman ◽  
K. Luxa ◽  
K. Sweeney ◽  
...  
Keyword(s):  
Energy Density ◽  
Population Trend ◽  
Population Trends ◽  
Aleutian Islands ◽  
Eumetopias Jubatus ◽  
Steller Sea Lions ◽  
Sea Lion ◽  
Diet Diversity ◽  
Sea Lions ◽  
Using Data

Prey diversity and energy density have been linked to each other and to population trends in many studies of bird and mammal diets. We re-examined these relationships in Steller sea lions (Eumetopias jubatus (Schreber, 1776)) using data collected from the Aleutian Islands, where there has been a strong longitudinal gradient in population trend. Diet diversity and energy density metrics were similar in the western Aleutians, where sea lion counts declined consistently, and in the easternmost Aleutian area, where population trends improved significantly. We compared traditional deterministic diet diversity metrics with diversity scores based on an occupancy model that accounts for differences in sample size and uncertainty in prey group detection. This analysis indicated that there was no significant change in diet diversity over the 23-year study period or any significant differences across the Aleutian Islands. These results are consistent with prey abundance data from nine groundfish bottom trawl surveys conducted over the same period. While diet studies detail what Steller sea lions eat and provide an estimate of their energy intake, they provide only limited information on the energy expended to obtain their food or the consequences of their diet and foraging ecology on individual or population fitness.

Demographic independence along ecosystem boundaries in Steller sea lions revealed by mtDNA analysis: implications for management of an endangered species

2006 ◽  
Vol 84 (12) ◽  
pp. 1796-1809 ◽  
Author(s):  
G. O’Corry-Crowe ◽  
B.L. Taylor ◽  
T. Gelatt ◽  
T.R. Loughlin ◽  
J. Bickham ◽  
...  
Keyword(s):  
Foraging Ecology ◽  
Gulf Of Alaska ◽  
Ocean Basin ◽  
Population Trends ◽  
Population Declines ◽  
Steller Sea Lions ◽  
Dispersal Patterns ◽  
Sea Lions ◽  
Ecosystem Boundaries ◽  
Haplotypic Diversity

Previous genetic studies indicate Steller sea lions ( Eumetopias jubatus (Schreber, 1776)) comprise three phylogeographically distinct populations. However, differences in population trends and ecology and the limited extent of recorded dispersal suggest structure may be present at smaller scales. We examined sequence variation within a longer segment (531 bp) of the mtDNA control region in greater numbers (n = 1654) of sea lions from across Alaska than earlier investigations to investigate fine-scale dispersal patterns in Steller sea lions. We detected high levels of haplotypic diversity (h = 0.934) and confirmed phylogeographic differentiation between southeastern and western Alaska (Φst = 0.23, P < 0.0001), but also found significant differentiation at regional and local scales. Rookeries in the Gulf of Alaska, eastern Bering Sea, and eastern Aleutians were distinct from rookeries in the central and western Aleutians (Fst = 0.021, P < 0.0001; Φst = 0.017, P < 0.0001). The location of this split coincides with an oceanographic divergence between continental shelf and ocean basin waters and with differences in sea lion foraging ecology and population trends. A number of rookeries were also significantly differentiated from nearby rookeries (Fst = 0.02–0.025, P < 0.05), signifying substantial female-mediated philopatry, in some cases, at local scales. These findings have important implications for understanding the ecology of Steller sea lions in relation to marine ecosystems and the causes of population declines, and they provide guidance for management, including the identification of management stocks.

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