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Lorrie D Rea - One of the best experts on this subject based on the ideXlab platform.
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organochlorine contaminant concentrations in blubber of young Steller Sea Lion eumetopias jubatus are influenced by region age sex and lipid stores
Science of The Total Environment, 2020Co-Authors: Mandy Keogh, Kimberlee B Beckmen, Lorrie D Rea, Brian S Fadely, Gina M Ylitalo, Brian D. Taras, Kathleen A Burekhuntington, Kenneth W PitcherAbstract:Contaminant exposure is particularly important for species and populations of conservation concern, such as the Steller Sea Lion (Eumetopias jubatus). We used blubber samples (n = 120) to determine organochlorine concentrations, including polychlorinated biphenyls (PCBs) and dichloro-diphenyl-trichloroethane (DDTs), and blood samples (n = 107) to estimate total body lipids based on the hydrogen isotope dilution method. We assessed the influence of age, sex, condition, and geographic area on contaminant concentrations in blubber and contaminant body load. The concentration of ΣPCBs was highest in pups (<6 months) from the Aleutian Islands, and the concentrations in males were higher than females in all regions. The ΣPCBs and ΣDDTs concentrations and loads decreased with increasing mass in pups, however, there were no regional or sex differences in contaminant load. Within each of the five age classes, the concentrations of ΣPCBs and ΣDDTs decreased with increasing mass, but overall these OCs increased with age. Further, accounting for the lipid content, a potential proxy for energy balance, in the animal load reduced or removed the regional and sex effects present in age models for contaminants. We propose, that adjusting OCs concentration by the lipid content of the blubber sample alone may not fully account for the variability in OC concentrations associated with differences in condition or energy states between young Steller Sea Lions.
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enhanced quantification of serum immunoglobulin g from a non model wildlife species the Steller Sea Lion eumetopias jubatus using a protein a elisa
Journal of Immunological Methods, 2018Co-Authors: Stephanie N Kennedy, Lorrie D Rea, Margaret J Castellini, Brittany Wilhite, Thomas Kuhn, Andrea Ferrante, Todd M OharaAbstract:Immunoglobulins (Ig) are proteins that preserve immune homeostasis and are quantified to infer changes to the acquired humoral immune response in mammals. Measuring Ig in non-model wildlife for immune surveillance often requires ingenuity, and rigorous standardization of methodologies to provide reliable results especially when lacking species-specific reagents. We modified and optimized existing ELISA methodology utilizing the binding properties of Staphylococcus-derived Protein A (PrtA) to immunoglobulin G (IgG). We enhanced the assay for quantifying IgG in Steller Sea Lion (SSL) serum using critical quality control measures including dilution linearity, spike and percent recoveries, and internal controls. Of the modifications made, heat treatment of SSL serum enhanced accuracy and precision of IgG measurements by improving linearity and percent recovery in parallel dilutions and serum spikes. Purified canine IgG standard was not affected by heat inactivation. These results support that confounding serum proteins interfere with binding of PrtA with IgG demonstrating the need for heat treatment of serum to optimize IgG quantification using the PrtA-ELISA. Further, essential validation measures ensure proper assay performance. Consequently, the improved PrtA-ELISA provides species-independent IgG detection with validation criteria to enhance accuracy and precision for addressing future immunological questions in non-model wildlife in clinical, ecological, and conservation contexts.
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temporal records of diet diversity dynamics in individual adult female Steller Sea Lion eumetopias jubatus vibrissae
Oecologia, 2018Co-Authors: Andrew C Doll, Lorrie D Rea, Todd M Ohara, Brian D. Taras, Craig A Stricker, Andrew P Cyr, Susanne F Mcdermott, Todd Loomis, Brian S FadelyAbstract:Detailed information on the nutrition of free-ranging mammals contributes to the understanding of life history requirements, yet is often quite limited temporally for most species. Reliable dietary inferences can be made by analyzing the stable carbon (C) and nitrogen (N) isotopic values (δ13C and δ15N) of some consumer tissues; exactly which tissue is utilized dictates the inferential scope. Steller Sea Lion (SSL) vibrissae are grown continuously without shedding and thus provide a continuous multi-year record of dietary consumption. We applied a novel kernel density approach to compare the δ13C and δ15N values along the length of SSL vibrissae with δ13C and δ15N distributions of potential prey species. This resulted in time-series of proportion estimates of dietary consumption for individual SSL. Substantial overlap in δ13C and δ15N distributions for prey species prevented a discrete species-scale assessment of SSL diets; however, a post hoc correlational analysis of diet proportion estimates revealed grouping by trophic level. Our findings suggest that adult female SSL diets in the western and central Aleutian Islands shift significantly according to Season: diets contain a higher proportion of lower trophic level species (Pacific Ocean perch, northern rockfish, Atka mackerel and walleye pollock) in the summer, whereas in the winter SSL consume a much more diverse diet which includes a greater proportion of higher trophic level species (arrowtooth flounder, Kamchatka flounder, darkfin sculpin, Pacific cod, Pacific octopus, rock sole, snailfish, and yellow Irish lord).
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Overwintering Steller Sea Lion (Eumetopias jubatus) pup growth and behavior prior to weaning
Canadian Journal of Zoology, 2018Co-Authors: Michael J Rehberg, Lorrie D Rea, Carrie EischensAbstract:We measured individual growth, looked for evidence of weaning and examined the interaction of these changes with diving behavior in young-of-year Steller Sea Lion pups (Eumetopias jubatus (Schreber, 1776)) in Alaska during their first winter. Steller Sea Lions employ an income breeding strategy, in which females provision their young over an individually variable period of months to years. Thus we set out to identify whether these young Sea Lions showed evidence of weaning during the challenging winter months, describe the nature of their growth during this time, and examine their behaviors in light of these changes. Between 2005 and 2008 we captured 71 pups during early winter and recaptured 33 of these pups in early spring. Mark-resight and stable nitrogen isotope ratios in vibrissae indicated most pups remained nutritionally dependent on adult females throughout the winter. All pups increased both mass and lipid mass, with half of growth contributed by lipid mass. Changes in behavior were not correlate...
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serum chemistry reference ranges for Steller Sea Lion eumetopias jubatus pups from alaska stock differentiation and comparisons within a north pacific sentinel species
Ecohealth, 2013Co-Authors: Michelle E Lander, Lorrie D Rea, Tom Gelatt, Brian S Fadely, Thomas R. LoughlinAbstract:Blood chemistry and hematologic reference ranges are useful for population health assessment and establishing a baseline for future comparisons in the event of ecosystem changes due to natural or anthropogenic factors. The objectives of this study were to determine if there was any population spatial structure for blood variables of Steller Sea Lion (Eumetopias jubatus), an established sentinel species, and to report reference ranges for appropriate populations using standardized analyses. In addition to comparing reference ranges between populations with contrasting abundance trends, data were examined for evidence of diSease or nutritional stress. From 1998 to 2011, blood samples were collected from 1,231 pups captured on 37 rookeries across their Alaskan range. Reference ranges are reported separately for the western and eastern distinct population segments (DPS) of Steller Sea Lion after cluster analysis and discriminant function analysis (DFA) supported underlying stock structure. Variables with greater loading scores for the DFA (creatinine, total protein, calcium, albumin, cholesterol, and alkaline phosphatase) also were greater for Sea Lions from the endangered western DPS, supporting previous studies that indicated pup condition in the west was not compromised during the first month postpartum. Differences between population segments were likely a result of ecological, physiological, or age related differences.
Thomas R. Loughlin - One of the best experts on this subject based on the ideXlab platform.
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serum chemistry reference ranges for Steller Sea Lion eumetopias jubatus pups from alaska stock differentiation and comparisons within a north pacific sentinel species
Ecohealth, 2013Co-Authors: Michelle E Lander, Lorrie D Rea, Tom Gelatt, Brian S Fadely, Thomas R. LoughlinAbstract:Blood chemistry and hematologic reference ranges are useful for population health assessment and establishing a baseline for future comparisons in the event of ecosystem changes due to natural or anthropogenic factors. The objectives of this study were to determine if there was any population spatial structure for blood variables of Steller Sea Lion (Eumetopias jubatus), an established sentinel species, and to report reference ranges for appropriate populations using standardized analyses. In addition to comparing reference ranges between populations with contrasting abundance trends, data were examined for evidence of diSease or nutritional stress. From 1998 to 2011, blood samples were collected from 1,231 pups captured on 37 rookeries across their Alaskan range. Reference ranges are reported separately for the western and eastern distinct population segments (DPS) of Steller Sea Lion after cluster analysis and discriminant function analysis (DFA) supported underlying stock structure. Variables with greater loading scores for the DFA (creatinine, total protein, calcium, albumin, cholesterol, and alkaline phosphatase) also were greater for Sea Lions from the endangered western DPS, supporting previous studies that indicated pup condition in the west was not compromised during the first month postpartum. Differences between population segments were likely a result of ecological, physiological, or age related differences.
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spatial patterns and scaling behaviors of Steller Sea Lion eumetopias jubatus distributions and their environment
Journal of Theoretical Biology, 2011Co-Authors: Michelle E Lander, Thomas R. Loughlin, Miles L Logsdon, Glenn R Van BlaricomAbstract:Abstract Fractal geometry and other multi-scale analyses have become popular tools for investigating spatial patterns of animal distributions in heterogeneous environments. In theory, changes in patterns of animal distributions with changes in scale reflect transitions between the controlling influences of one environmental factor or process over another. In an effort to find linkages between Steller Sea Lions (Eumetopias jubatus) and their environment, the objective of this study was to determine if the spatial distribution of Steller Sea Lions at Sea displayed similar scaling properties to the variation of two environmental features, including bathymetry and Sea surface temperature (SST). Additionally, distributions of Steller Sea Lion point patterns were examined with respect to measurements of bathymetric complexity. From February 2000 to May 2004, satellite transmitters were deployed on 10 groups of juvenile Steller Sea Lions (n=52) at eight different locations within the Aleutian Islands and Gulf of Alaska. Indices of fractal dimension were calculated for each group of Sea Lions using a unit square box-counting method, whereas indices of bathymetry and SST patchiness were derived by conducting a variance ratio analysis over the same scales. Distributions of Steller Sea Lions at Sea displayed self-similar fractal patterns, suggesting that individuals were distributed in a continuous hierarchical set of clumps within clumps across scales, and foraging behavior was likely influenced by a scale invariant mechanism. Patterns of bathymetric variability also were self-similar, whereas patterns of SST variability were scale dependent and failed to retain self-similar spatial structure at larger scales. These results indicate that the distributions of Steller Sea Lions at Sea were more influenced by bathymetry than SST at the scales examined, but scale-dependent patterns in the distribution of Steller Sea Lions at Sea or linkages with SST may have been apparent if analyses were conducted at finer spatial scales.
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Steller Sea Lion: Eumetopias jubatus
Encyclopedia of Marine Mammals, 2009Co-Authors: Thomas R. LoughlinAbstract:Publisher Summary The Steller Sea Lion, Eumetopias jubatus, is the largest otariid pinniped and one of the more aesthetically appealing Sea Lions. It exhibits significant sexual dimorphism with males larger. The average standard length of males is 282 cm and of females 228 cm. Estimated average weight of males is 566 kg and of females 263 kg. The upper postcanine number 5 is double rooted, with the crown directed backward, and does not occlude with lower postcanine 5; all other postcanines are single rooted, slant somewhat forward, and have irregular conical pointed crowns. Steller Sea Lions occur throughout the North Pacific Ocean rim from Japan to southern California. They abound on numerous breeding sites (rookeries) in the Russian Far East, Alaska, and British Columbia, with lower numbers in Oregon and California. Steller Sea Lions eat a variety of fishes and invertebrates. The variety of the Sea Lion diet has been correlated with population dynamics. A cacophony of noise engulfs rookeries and haul-out sites, with animals of both sexes and all ages vocalizing throughout the day and night. Territorial males use low-frequency roars to signal threats to other males and to court females. Females vocalize frequently, calling to their pups and squabbling with other Sea Lions of all ages. Observations at Sea suggest that large groups usually consist of females of all ages and subadult males; adult males sometimes occur in those groups but are usually found individually. On land, all ages and both sexes occur in large aggregations during the nonbreeding Season. Breeding Season aggregations are segregated by sexual/territorial status. Steller Sea Lions are rarely seen in aquaria because of their large size and pugnacious nature. The species is an important subsistence resource for Alaskan natives, who hunt Sea Lions for food and other uses. Two hundred or more may be taken a year in Alaska.
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bacular size growth and allometry in the largest extant otariid the Steller Sea Lion eumetopias jubatus
Journal of Mammalogy, 2000Co-Authors: Edward H Miller, Kenneth W Pitcher, Thomas R. LoughlinAbstract:Bacula are relatively small in terrestrially mating species of pinnipeds (otariids and elephant Seals, Mirounga), perhaps reflecting adaptive size reduction to minimize bacular fracture. Fur Seals and Sea Lions (Otariidae) are a good group with which to investigate this question, because most species copulate solely on land and body size varies interspecifically. We studied bacular size and relative growth in the largest extant otariid, the Steller Sea Lion (Eumetopias jubatus). Bacula roughly tripled in length and increased 30-fold in mass between 1 and 8 years of age. Allometric relationships changed over development; bacular length and mass changed from being initially positively allometric to body length to negatively allometric and isometric, respectively; bacular mass and thickness were positively allometric to body length throughout life, and apical growth was isometric then was positively allometric to bacular length. In adults ( .7 years of age), bacula averaged 18.1 cm length (6.2% of body length), 36.7 g mass, and 2.02 g/cm density (mass : length). The baculum of Eumetopias is about the same length relative to body length as in other adult male otariids but is about twice the density, presumably to increase strength. Information on small or aquatically mating species of otariid are needed to extend our findings and interpretations.
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health status of young alaska Steller Sea Lion pups eumetopias jubatus as indicated by blood chemistry and hematology
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 1998Co-Authors: Michael A Castellini, Lorrie D Rea, Brian S Fadely, Thomas R. LoughlinAbstract:Blood chemistry and hematology were examined in 238 Steller Sea Lion pups (Eumetopias jubatus) to assess the health status of pups < 1 month of age. Failure of juvenile recruitment (possibly due to nutritionally or physiologically compromised pups) into breeding populations has been proposed as a cause of recent declines of this endangered species in Alaska. To identify potential correlations with areas of high population decline, blood chemistry data were considered for three areas: eastern Aleutian Islands (low rates of population decline to stable populations), Gulf of Alaska (high rates of decline), and Southeast Alaska (stable to increasing population). Southeast Alaska pups showed elevated ketone body concentrations (β-hydroxybutyrate, (β -HBA)) and depressed glucose levels when compared with animals from the Aleutian Islands and lower blood urea nitrogen (BUN) and glucose levels than pups in the Gulf of Alaska. Over 40% of the pups from Southeast Alaska had elevated β -HBA concentrations suggesting they underwent longer periods of fasting than seen in pups from other areas. Hematocrit (Hct), hemoglobin concentration (Hb) and water content of the blood exhibited typical mammalian relationships. In summary, blood chemistry and hematology data showed no indication that Steller Sea Lion pups < 1 month old from areas of population decline were nutritionally compromised. © 1998 Elsevier Science Inc. All rights reserved.
Brian S Fadely - One of the best experts on this subject based on the ideXlab platform.
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organochlorine contaminant concentrations in blubber of young Steller Sea Lion eumetopias jubatus are influenced by region age sex and lipid stores
Science of The Total Environment, 2020Co-Authors: Mandy Keogh, Kimberlee B Beckmen, Lorrie D Rea, Brian S Fadely, Gina M Ylitalo, Brian D. Taras, Kathleen A Burekhuntington, Kenneth W PitcherAbstract:Contaminant exposure is particularly important for species and populations of conservation concern, such as the Steller Sea Lion (Eumetopias jubatus). We used blubber samples (n = 120) to determine organochlorine concentrations, including polychlorinated biphenyls (PCBs) and dichloro-diphenyl-trichloroethane (DDTs), and blood samples (n = 107) to estimate total body lipids based on the hydrogen isotope dilution method. We assessed the influence of age, sex, condition, and geographic area on contaminant concentrations in blubber and contaminant body load. The concentration of ΣPCBs was highest in pups (<6 months) from the Aleutian Islands, and the concentrations in males were higher than females in all regions. The ΣPCBs and ΣDDTs concentrations and loads decreased with increasing mass in pups, however, there were no regional or sex differences in contaminant load. Within each of the five age classes, the concentrations of ΣPCBs and ΣDDTs decreased with increasing mass, but overall these OCs increased with age. Further, accounting for the lipid content, a potential proxy for energy balance, in the animal load reduced or removed the regional and sex effects present in age models for contaminants. We propose, that adjusting OCs concentration by the lipid content of the blubber sample alone may not fully account for the variability in OC concentrations associated with differences in condition or energy states between young Steller Sea Lions.
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Organochlorine contaminant concentrations in blubber of young Steller Sea Lion (Eumetopias jubatus) are influenced by region, age, sex, and lipid stores
Science of The Total Environment, 2019Co-Authors: Mandy Keogh, Kimberlee B Beckmen, Brian S Fadely, Gina M Ylitalo, Brian D. Taras, Kathleen A. Burek-huntington, Kenneth W PitcherAbstract:Abstract Contaminant exposure is particularly important for species and populations of conservation concern, such as the Steller Sea Lion (Eumetopias jubatus). We used blubber samples (n = 120) to determine organochlorine concentrations, including polychlorinated biphenyls (PCBs) and dichloro-diphenyl-trichloroethane (DDTs), and blood samples (n = 107) to estimate total body lipids based on the hydrogen isotope dilution method. We assessed the influence of age, sex, condition, and geographic area on contaminant concentrations in blubber and contaminant body load. The concentration of ΣPCBs was highest in pups (
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temporal records of diet diversity dynamics in individual adult female Steller Sea Lion eumetopias jubatus vibrissae
Oecologia, 2018Co-Authors: Andrew C Doll, Lorrie D Rea, Todd M Ohara, Brian D. Taras, Craig A Stricker, Andrew P Cyr, Susanne F Mcdermott, Todd Loomis, Brian S FadelyAbstract:Detailed information on the nutrition of free-ranging mammals contributes to the understanding of life history requirements, yet is often quite limited temporally for most species. Reliable dietary inferences can be made by analyzing the stable carbon (C) and nitrogen (N) isotopic values (δ13C and δ15N) of some consumer tissues; exactly which tissue is utilized dictates the inferential scope. Steller Sea Lion (SSL) vibrissae are grown continuously without shedding and thus provide a continuous multi-year record of dietary consumption. We applied a novel kernel density approach to compare the δ13C and δ15N values along the length of SSL vibrissae with δ13C and δ15N distributions of potential prey species. This resulted in time-series of proportion estimates of dietary consumption for individual SSL. Substantial overlap in δ13C and δ15N distributions for prey species prevented a discrete species-scale assessment of SSL diets; however, a post hoc correlational analysis of diet proportion estimates revealed grouping by trophic level. Our findings suggest that adult female SSL diets in the western and central Aleutian Islands shift significantly according to Season: diets contain a higher proportion of lower trophic level species (Pacific Ocean perch, northern rockfish, Atka mackerel and walleye pollock) in the summer, whereas in the winter SSL consume a much more diverse diet which includes a greater proportion of higher trophic level species (arrowtooth flounder, Kamchatka flounder, darkfin sculpin, Pacific cod, Pacific octopus, rock sole, snailfish, and yellow Irish lord).
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serum chemistry reference ranges for Steller Sea Lion eumetopias jubatus pups from alaska stock differentiation and comparisons within a north pacific sentinel species
Ecohealth, 2013Co-Authors: Michelle E Lander, Lorrie D Rea, Tom Gelatt, Brian S Fadely, Thomas R. LoughlinAbstract:Blood chemistry and hematologic reference ranges are useful for population health assessment and establishing a baseline for future comparisons in the event of ecosystem changes due to natural or anthropogenic factors. The objectives of this study were to determine if there was any population spatial structure for blood variables of Steller Sea Lion (Eumetopias jubatus), an established sentinel species, and to report reference ranges for appropriate populations using standardized analyses. In addition to comparing reference ranges between populations with contrasting abundance trends, data were examined for evidence of diSease or nutritional stress. From 1998 to 2011, blood samples were collected from 1,231 pups captured on 37 rookeries across their Alaskan range. Reference ranges are reported separately for the western and eastern distinct population segments (DPS) of Steller Sea Lion after cluster analysis and discriminant function analysis (DFA) supported underlying stock structure. Variables with greater loading scores for the DFA (creatinine, total protein, calcium, albumin, cholesterol, and alkaline phosphatase) also were greater for Sea Lions from the endangered western DPS, supporting previous studies that indicated pup condition in the west was not compromised during the first month postpartum. Differences between population segments were likely a result of ecological, physiological, or age related differences.
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maternal Steller Sea Lion diets elevate fetal mercury concentrations in an area of population decline
Science of The Total Environment, 2013Co-Authors: Margaret J Castellini, Lucero Correa, Brian S Fadely, Todd M OharaAbstract:Abstract Total mercury concentrations ([THg]) measured in western Aleutian Island Steller Sea Lion pup hair were the highest maximum [THg] documented in this endangered species to date. Some pups exceeded concentrations at which other fish-eating mammals can exhibit adverse neurological and reproductive effects (21% and 15% pups above 20 and 30 μg/g in hair, respectively). Of particular concern is fetal exposure to mercury during a particularly vulnerable stage of neurological development in late gestation. Hair and blood [THg] were highly correlated and 20% of pups sampled in the western Aleutian Islands of Alaska exceeded mammalian risk thresholds established for each of these tissues. Higher nitrogen isotope ratios suggested that pups accumulated the highest [THg] when their dams fed on higher trophic level prey during late gestation.
Andrew W. Trites - One of the best experts on this subject based on the ideXlab platform.
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Steller Sea Lion foraging response to Seasonal changes in prey availability
Marine Ecology Progress Series, 2009Co-Authors: Michael F. Sigler, Johanna J Vollenweider, John F Thedinga, David J Csepp, Jamie N Womble, Mandy Wong, Michael J Rehberg, Dominic J Tollit, Andrew W. TritesAbstract:We hypothesized that: (1) Steller Sea Lion Eumetopias jubatus diet choice is a function of prey availability, (2) Sea Lions move to take advantage of times and locations of Seasonal prey concentrations and (3) the number present depends on the amount of prey available (numerical response). Over 3 yr, typically on a quarterly basis, in Frederick Sound, SE Alaska, multiple measurements were taken of Steller Sea Lion abundance (aerial surveys), diet (scats), dive behavior (satellite telemetry) and prey availability and caloric density (nearshore, pelagic and demersal fish surveys). We found that Steller Sea Lions shifted diet composition in response to changes in prey availability of pollock Theragra chalcogramma, hake Merluccius productus, herring Clupea pallasi and salmon Oncorhynchus spp. They selected intermediate-sized fish and avoided small ( 60 cm) fish, and moved between areas as prey became available Seasonally. The number of Sea Lions present depended on the amount of prey available; a standing biomass of 500 to 1700 t of prey in a nonbreeding area such as Frederick Sound, depending on species composition, can attract and sustain about 500 Sea Lions. Pollock was more frequent in Sea Lion diet in inside waters of SE Alaska — including Frederick Sound, Stephens Passage and Lynn Canal — than anywhere else in Alaska and contributed ~⁄3 of the dietary energy in Frederick Sound. This finding implies that a diet with substantial year-round contributions from less nutritious, but abundant prey such as pollock can form part of a healthy diet as long as more nutritious prey such as herring, salmon or eulachon Thaleichthys pacificus also are consumed. Our study supports the conclusion that the Steller Sea Lion is an opportunistic marine predator with a flexible foraging strategy that selects abundant, accessible prey and shifts among Seasonally available species.
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Steller Sea Lion foraging response to Seasonal changes in prey availability
Marine Ecology Progress Series, 2009Co-Authors: Michael F. Sigler, Johanna J Vollenweider, John F Thedinga, David J Csepp, Jamie N Womble, Mandy Wong, Michael J Rehberg, Dominic J Tollit, Andrew W. TritesAbstract:We hypothesized that: (1) Steller Sea Lion Eumetopias jubatus diet choice is a function of prey availability, (2) Sea Lions move to take advantage of times and locations of Seasonal prey concentrations and (3) the number present depends on the amount of prey available (numerical response). Over 3 yr, typically on a quarterly basis, in Frederick Sound, SE Alaska, multiple measurements were taken of Steller Sea Lion abundance (aerial surveys), diet (scats), dive behavior (satellite telemetry) and prey availability and caloric density (nearshore, pelagic and demersal fish surveys). We found that Steller Sea Lions shifted diet composition in response to changes in prey availability of pollock Theragra chalcogramma, hake Merluccius productus, herring Clupea pallasi and salmon Oncorhynchus spp. They selected intermediate-sized fish and avoided small ( 60 cm) fish, and moved between areas as prey became available Seasonally. The number of Sea Lions present depended on the amount of prey available; a standing biomass of 500 to 1700 t of prey in a nonbreeding area such as Frederick Sound, depending on species composition, can attract and sustain about 500 Sea Lions. Pollock was more frequent in Sea Lion diet in inside waters of SE Alaska — including Frederick Sound, Stephens Passage and Lynn Canal — than anywhere else in Alaska and contributed ~⁄3 of the dietary energy in Frederick Sound. This finding implies that a diet with substantial year-round contributions from less nutritious, but abundant prey such as pollock can form part of a healthy diet as long as more nutritious prey such as herring, salmon or eulachon Thaleichthys pacificus also are consumed. Our study supports the conclusion that the Steller Sea Lion is an opportunistic marine predator with a flexible foraging strategy that selects abundant, accessible prey and shifts among Seasonally available species.
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a novel presence only validation technique for improved Steller Sea Lion eumetopias jubatus critical habitat descriptions
Marine Ecology Progress Series, 2008Co-Authors: Edward J Gregr, Andrew W. TritesAbstract:We used published information about foraging behaviour, terrestrial resting sites, bathymetry and Seasonal ocean climate to develop hypotheses relating life-history traits and physical variables to the at-Sea habitat of a wide-ranging marine predator, the Steller Sea Lion Eumetopias jubatus. We used these hypotheses to develop a series of habitat models predicting the probability of Sea Lions occurring within a 3 × 3 km 2 grid in the Gulf of Alaska and the Bering Sea. We compared these deductive model predictions with opportunistic at-Sea observations of Sea Lions (presence-only data) using (1) a likelihood approach in a small area where effort was assumed to be uniformly distributed and (2) an adjusted skewness (Skadj) test that evaluated the distribution of the predicted values associated with true presence observations. We found that the Skadj statistic was comparable to the likelihood test when using pseudo-absence data, but it was more powerful for assessing the relative performance of the different predictive spatial models across the entire study area. The habi- tat maps we produced for adult female Sea Lions using the deductive modelling approach captured a higher proportion of presence observations than the current habitat model (critical habitat) used by fisheries managers since 1993 to manage Steller Sea Lions. Such improved predictions of habitat are necessary to effectively design, implement and evaluate fishery mitigation measures. The deductive approach we propose is suitable for modelling the habitat use of other age and sex classes, and for integrating these age/sex-class-specific models into a revised definition of critical habitat for Steller Sea Lions. The skewness test provides a means of comparing the relative performance of such models, using presence-only data. The approach can be readily applied to other central-place foragers.
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suckling attempts during winter by two non filial Steller Sea Lion pups eumetopias jubatus
Mammalia, 2004Co-Authors: Boyd T Porter, Andrew W. TritesAbstract:Milk stealing and fostering care is rare among mammals (Packer et al. 1992). Such behaviour can benefit neonates and possibly the nursing foster mother (Roulin 2002, 2003). However, it also likely comes at a cost to the fostering mother and her dependent young. Neonates may increase their chances of survival by sneak-suckling unrelated females, or by obtaining milk with the consent of mothers of other neonates. However, chances are greater that females protective of their limited milk resources will aggressively prevent unrelated young from suckling. Risks of being bitten, attacked or killed by adult females presumably outweigh the potential benefits that might be achieved by sneak-suckling. Among pinnipeds, the nursing of offspring that are not their own (allosuckling) has been noted for some species of Seals, but rarely for Sea Lions or fur Seals. Only one case has so far been reported of a nonfilial Steller Sea Lion pup (Eumetopias jubatus) successfully obtaining milk, and the duration was only 30 seconds (Higgins 1984). Since this observation, thousands of hours have been spent observing Steller Sea Lions in the wild (Trites & Porter 2002; Milette & Trites 2003; Trites, unpubl. data), but only two additional successful suckling attempts have been noted. These two observations are noteworthy because of their rarity and the interest in understanding allosuckling in mammals (e.g., Roulin 2002,
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THE RELIABILITY OF SKINFOLD‐CALIPERS FOR MEASURING BLUBBER THICKNESS OF Steller Sea Lion PUPS (EUMETOPIAS JUBATUS)
Marine Mammal Science, 2000Co-Authors: Remco A. H. Jonker, Andrew W. TritesAbstract:Twelve dead Steller Sea Lion pups (Eumetopias jubatus) aged 3-14 d were recovered from rookeries in Southeast Alaska. They had a wide range of body sizes and conditions (small to large and fat to no fat). The ability of calipers to estimate the thickness of their blubber layer was assessed with a set of skinfold calipers. Average error of measurement for skin and blubber thickness was an acceptable 5.4%, but the skin and blubber of the pups were highly compressible. Skinfold thickness increased with body mass but did not necessarily reflect the development of blubber, given that pups with no blubber also showed an increase in skinfold thickness with increases in body mass. Skinfold thickness of Sea Lion pups appears to predict body size better than it predicts blubber thickness, making it difficult if not impossible to develop a simple index of body condition or a calculation of percent body fat for Steller Sea Lion pups from skinfold caliper measurements.
Kenneth W Pitcher - One of the best experts on this subject based on the ideXlab platform.
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organochlorine contaminant concentrations in blubber of young Steller Sea Lion eumetopias jubatus are influenced by region age sex and lipid stores
Science of The Total Environment, 2020Co-Authors: Mandy Keogh, Kimberlee B Beckmen, Lorrie D Rea, Brian S Fadely, Gina M Ylitalo, Brian D. Taras, Kathleen A Burekhuntington, Kenneth W PitcherAbstract:Contaminant exposure is particularly important for species and populations of conservation concern, such as the Steller Sea Lion (Eumetopias jubatus). We used blubber samples (n = 120) to determine organochlorine concentrations, including polychlorinated biphenyls (PCBs) and dichloro-diphenyl-trichloroethane (DDTs), and blood samples (n = 107) to estimate total body lipids based on the hydrogen isotope dilution method. We assessed the influence of age, sex, condition, and geographic area on contaminant concentrations in blubber and contaminant body load. The concentration of ΣPCBs was highest in pups (<6 months) from the Aleutian Islands, and the concentrations in males were higher than females in all regions. The ΣPCBs and ΣDDTs concentrations and loads decreased with increasing mass in pups, however, there were no regional or sex differences in contaminant load. Within each of the five age classes, the concentrations of ΣPCBs and ΣDDTs decreased with increasing mass, but overall these OCs increased with age. Further, accounting for the lipid content, a potential proxy for energy balance, in the animal load reduced or removed the regional and sex effects present in age models for contaminants. We propose, that adjusting OCs concentration by the lipid content of the blubber sample alone may not fully account for the variability in OC concentrations associated with differences in condition or energy states between young Steller Sea Lions.
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Organochlorine contaminant concentrations in blubber of young Steller Sea Lion (Eumetopias jubatus) are influenced by region, age, sex, and lipid stores
Science of The Total Environment, 2019Co-Authors: Mandy Keogh, Kimberlee B Beckmen, Brian S Fadely, Gina M Ylitalo, Brian D. Taras, Kathleen A. Burek-huntington, Kenneth W PitcherAbstract:Abstract Contaminant exposure is particularly important for species and populations of conservation concern, such as the Steller Sea Lion (Eumetopias jubatus). We used blubber samples (n = 120) to determine organochlorine concentrations, including polychlorinated biphenyls (PCBs) and dichloro-diphenyl-trichloroethane (DDTs), and blood samples (n = 107) to estimate total body lipids based on the hydrogen isotope dilution method. We assessed the influence of age, sex, condition, and geographic area on contaminant concentrations in blubber and contaminant body load. The concentration of ΣPCBs was highest in pups (
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Model selection results for estimating movement (ψ), survival (S) and resighting (p) probabilities for Steller Sea Lion females with pups at southeastern Alaska rookeries (SeaK, 2002–2015), and at Forrester Island Complex (F, 2005 and 2007–15).
2017Co-Authors: Kelly K Hastings, Grey W Pendleton, Lauri A. Jemison, Kimberly L. Raum-suryan, Kenneth W PitcherAbstract:Model selection results for estimating movement (ψ), survival (S) and resighting (p) probabilities for Steller Sea Lion females with pups at southeastern Alaska rookeries (SeaK, 2002–2015), and at Forrester Island Complex (F, 2005 and 2007–15).
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abundance and distribution of the eastern north pacific Steller Sea Lion eumetopias jubatus population
Fishery Bulletin, 2007Co-Authors: Kenneth W Pitcher, Robin F. Brown, Wayne L. Perryman, Peter F Olesiuk, Mark S Lowry, Steven J Jeffries, John L Sease, Charles E Stinchcomb, Lloyd F LowryAbstract:The eastern Steller Sea Lion (Eumetopias jubatus) population comprises animals that breed along the west coast of North America between California and southeastern Alaska. There are currently 13 major rookeries (>50 pups): five in southeastern Alaska, three in British Columbia, two in Oregon, and three in California. Overall abundance has increased at an average annual rate of 3.1% since the 1970s. These increases can largely be attributed to population recovery from predator-control kills and commercial harvests, and abundance is now probably as high as it has been in the last century. The number of rookeries has remained fairly constant (n=11 to 13) over the past 80 years, but there has been a northward shift in distribution of both rookeries and numbers of animals. Based on the number of pups counted in a population-wide survey in 2002, total pup production was estimated to be about 11,000 (82% in southeastern Alaska and British Columbia), representing a total population size as approximately 46,000−58,000 animal
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COUNTING Steller Sea Lion PUPS IN ALASKA: AN EVALUATION OF MEDIUMFORMAT, COLOR AERIAL PHOTOGRAPHY
Marine Mammal Science, 2001Co-Authors: Gary M. Snyder, Kenneth W Pitcher, Wayne L. Perryman, Morgan S. LynnAbstract:Estimates of Steller Sea Lion (Eumetopias jubatus) pup production are valuable for estimating population trend and size. Currently in Alaska, pups are counted by visiting rookeries, driving older animals into the water, then walking through the rookeries and counting the pups, a highly disruptive procedure. At smaller rookeries, with good vantage points, pups are occasionally counted from the periphery of rookeries without disturbing the Sea Lions. We evaluated counts made from medium-format, color, aerial photographs as an alternative to drive counts and peripheral counts. Neither the peripheral counts nor the aerial photographic counts disturbed animals on the rookeries. There were strong 1:1 linear relationships between photographic counts and drive counts (r 2 = 0.966, P < 0.001) and between photographic counts and peripheral counts (r2 = 0.999, P < 0.001). Precision was similar for all three methods of counting. We suggest that medium-format, color, aerial photography is appropriate for routine surveys of Steller Sea Lion pups in Alaska because it is not disruptive to the hauled-out Sea Lions and provides comparable estimates with similar precision to drive and peripheral counts. Large areas can be rapidly surveyed during periods of good weather with a minimum of manpower.
