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Andrew W. Trites - One of the best experts on this subject based on the ideXlab platform.
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REFERENCE RANGES AND AGE-RELATED AND DIVING EXERCISE EFFECTS ON HEMATOLOGY AND SERUM CHEMISTRY OF FEMALE STELLER SEA LIONS ( Eumetopias jubatus).
Journal of zoo and wildlife medicine : official publication of the American Association of Zoo Veterinarians, 2018Co-Authors: Carling D. Gerlinsky, Andrew W. Trites, Martin Haulena, David A S RosenAbstract:Abstract Decreased health may have lowered the birth and survival rates of Steller sea lions (Eumetopias jubatus) in the Gulf of Alaska and Aleutian Islands over the past 30 yr. Reference ranges for clinical hematology and serum chemistry parameters needed to assess the health of wild sea lion populations are limited. Here, blood parameters were serially measured in 12 captive female Steller sea lions ranging in age from 3 wk to 16 yr to establish baseline values and investigate age-related changes. Whether diving activity affects hematology parameters in animals swimming in the ocean compared with animals in a traditional aquarium setting was also examined. Almost all blood parameters measured exhibited significant changes with age. Many of the age-related changes reflected developmental life history changes, including a change in diet during weaning, an improvement of diving capacity, and the maturity of the immune system. Mean corpuscular hemoglobin and mean corpuscular volume were also higher in the o...
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Swimming depth and ocean currents affect transit costs in Steller sea lions Eumetopias jubatus
Aquatic Biology, 2010Co-Authors: Allyson G. Hindle, David A S Rosen, Andrew W. TritesAbstract:Transit costs associated with commuting between resting sites ashore and foraging areas at sea constitute an appreciable portion of foraging expenditures in pinnipeds. We examined transit swimming in 3 Steller sea lions Eumetopias jubatus trained to follow a moving boat at differ- ent speeds and depths. We measured dive behavior (duration) and focused specifically on activity measures (fore-flipper stroking and overall dynamic body acceleration (ODBA), an overall measure of body motion), which may be proxies for metabolic expenditure. Sea lions appeared to increase effi- ciency while transiting at depths that approached 3 times their body diameters (mean depth = 151 ± 1 cm SEM, n = 87). Although the response was not uniform for all tested scenarios, all of the observed significant adjustments to dive behavior and swimming mechanics supported an increased efficiency at this depth. An increase in transit speed (4.5 versus 3.5 knots (kn) surface speed) was associated with elevated flipper stroke frequencies (+5%) and stroke output (ODBA stroke -1 , +48%). Sea lions transiting against the flow of a tidal current had reduced dive durations (-10%), while total ODBA was consistently elevated (+8% overall). This response to tidal flow was accompanied either by ele- vated ODBA stroke -1 (3.5 kn) or a parallel increase in stroking (4.5 kn). Our data demonstrate that small changes in the physical environment affect transiting in Steller sea lions, and imply that altered prey fields or changing ocean conditions can carry energetic consequences.
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Fasting affects the surface and diving metabolic rates of Steller sea lions Eumetopias jubatus
Aquatic Biology, 2009Co-Authors: Caroline Svard, Andreas Fahlman, David A S Rosen, Ruth Joy, Andrew W. TritesAbstract:Changes in metabolic rates were measured in 3 captive female Steller sea lions Eumetopias jubatus that experienced fasts during summer and winter. We measured metabolic rates (via O2 consumption) before (MRs, surface) and after (DMR, dive + surface interval) the sea lions dove to 10–50 m depths. Measurements were obtained prior to and immediately after 9 to 10 d fasts, and during a 14 d recovery period. The sea lions lost significantly more body mass (Mb) during the winter fast (10.6%), compared with the summer (9.5%). Mass-corrected dive metabolic rate (cDMR = DMR × Mb–0.714) was not affected by dive depth or duration, but increased significantly following the winter fasts (13.5 ± 8.1%), but did not change during summer (–1.1 ± 3.2%). However, mass-corrected surface metabolic rate (cMRs) decreased significantly after both the summer (–16.4 ± 4.7%) and winter (–8.0 ± 9.0%) fasts. Consequently, the ratio between cDMR and cMRs was significantly higher in winter, suggestive of an increased thermal challenge and convective heat loss while diving. Increased cMRs following the fast indicated that digestion began during foraging and was not deferred, implying that access to ingested energy was of higher priority than optimizing diving ability. cDMR was elevated throughout the recovery period, independent of season, resulting in a 12% increase in foraging cost in winter and a 3% increase in summer. Our data suggest that Steller sea lions are more sensitive to changes in body condition due to food shortages in the winter compared with the summer.
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Seasonal differences in biochemical adaptation to fasting in juvenile and subadult Steller sea lions (Eumetopias jubatus).
Physiological and biochemical zoology : PBZ, 2009Co-Authors: Lorrie D Rea, David A S Rosen, Michelle Berman‐kowalewski, Andrew W. TritesAbstract:Abstract Nine Steller sea lions (Eumetopias jubatus) aged 1.75–6 yr were experimentally fasted for 7–14 d during the breeding and nonbreeding seasons to identify changes in plasma metabolites that are indicative of fasting and to determine whether the ability of sea lions to fast varies seasonally or with age. Although some animals approached the limit of their protein‐sparing ability by the end of our fasting experiments, there was no sign of irreversible starvation biochemistry. Plasma blood urea nitrogen (BUN) concentrations decreased in all animals within the first week of fasting, reflecting a shift to a fasting‐adapted state; however, significant increases in plasma BUN concentration at the end of the nonbreeding season fasts suggest that subadult Steller sea lions were not able to maintain a protein‐sparing metabolism for a full 14 d during the nonbreeding season. In contrast, juveniles were able to enter protein sparing sooner during the nonbreeding season when they had slightly higher initial per...
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Buoyancy does not affect diving metabolism during shallow dives in Steller sea lions Eumetopias jubatus
Aquatic Biology, 2008Co-Authors: Andreas Fahlman, David A S Rosen, Gordon D. Hastie, Yasuhiko Naito, Andrew W. TritesAbstract:Changes in buoyancy due to seasonal or abnormal changes in body composition are thought to significantly affect the energy budget of marine mammals through changes in diving costs. We assessed how changes in body composition might alter the foraging efficiency of Steller sea lions Eumetopias jubatus by artificially adjusting the buoyancy of trained individuals. PVC tubes were attached to harnesses worn by Steller sea lions that had been trained to feed at fixed depths (10 to 30 m) and to resurface inside a metabolic dome. Buoyancy was altered to simulate the naturally occurring differences in body composition reported in adult females (~12 to 26% subcutaneous fat). Diving characteristics (transit times and time at depth) and aerobic energy expenditure (gas exchange) were measured. We found that foraging cost decreased with the duration of the dive and increased with dive depth. However, changes in body composition did not affect the diving metabolic rate of Steller sea lions for dives between 10 and 30 m. We propose that Steller sea lions may adjust their diving lung volume to compensate for changes in buoyancy to avoid additional metabolic costs.
Lorrie D Rea - One of the best experts on this subject based on the ideXlab platform.
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Assessing oxidative stress in Steller sea lions (Eumetopias jubatus): Associations with mercury and selenium concentrations.
Comparative biochemistry and physiology. Toxicology & pharmacology : CBP, 2020Co-Authors: Marianne Lian, Lorrie D Rea, Brian S Fadely, Mandy Keogh, J. Margaret Castellini, Thomas Kuhn, Louise Bishop, Stephanie N. Kennedy, Edwin Van Wijngaarden, John M. ManiscalcoAbstract:Abstract Selenium (Se) bioavailability is required for synthesis and function of essential Se-dependent antioxidants, including the enzyme glutathione peroxidase (GPx). Strong interactions between monomethyl mercury and Se impair the critical antioxidant role of Se. Approximately 20% of Steller sea lion (Eumetopias jubatus, SSL) pups sampled in the western Aleutian Islands, Alaska, had total Hg concentrations ([THg]) measured in hair and whole blood above thresholds of concern for adverse physiologic effects in pinnipeds. Importantly, low molar ratios of TSe:THg, in some cases
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REGIONAL AND AGE-RELATED VARIATIONS IN HAPTOGLOBIN CONCENTRATIONS IN STELLER SEA LIONS (Eumetopias jubatus) FROM ALASKA, USA
Journal of wildlife diseases, 2018Co-Authors: Stephanie N. Kennedy, Vladimir N Burkanov, Brian S Fadely, Todd M. O'hara, J. Margaret Castellini, Alison B. Hayden, Andres Dajles, Lorrie D ReaAbstract:Varying concentrations of the highly conserved acute phase response protein, haptoglobin, can indicate changes to the health and disease status of mammals, including the Steller sea lion (SSL; Eumetopias jubatus). To better understand factors relating to acute phase response in SSLs, circulating haptoglobin concentrations (Hp) were quantified in plasma collected from 1,272 individuals sampled near rookeries and haulouts off the coast of Alaska, US. We compared Hp in SSLs between sexes and among different age classes (young pups, young-of-the-year, yearlings, subadults, and adults) sampled within distinct regions in Alaska (Aleutian Islands, Gulf of Alaska, Southeast Alaska). Regional and agerelated differences were observed, particularly in younger SSLs. No sex-related differences were detected. We identified weakly significant relationships between Hp and hematology measurements including white blood cell counts and hematocrit in young pups from the Aleutian Islands and Southeast Alaska. No relationship between Hp and body condition was found. Lastly, a nonlinear relationship of plasma Hp and whole blood total mercury concentrations (THg) was observed in SSLs from the endangered western distinct population segment in Alaska. These results demonstrated that regional variation in Hp, especially in younger SSLs, may reflect regional differences in health and circulating THg.
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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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field anesthesia of juvenile steller sea lions Eumetopias jubatus using inhalation anesthesia
Marine Mammal Science, 2018Co-Authors: Marianne Lian, Tom Gelatt, Kimberlee B Beckmen, Lorrie D Rea, Shawn P. Johnson, Todd M OharaAbstract:Between 1998 and 2008, 621 Steller sea lions (Eumetopias jubatus, SSL) were captured underwater by SCUBA divers and anesthetized with isoflurane (n = 602) or sevoflurane (n = 19). We found significantly faster induction time (X ± SD) for sevoflurane (11 ± 6 min) compared to isoflurane (14 ± 6 min), as well as an interaction between anesthetists using the isoflurane protocol. Severe hypothermia with temperatures <35°C were measured in 22% of all animals, and had significant associations with month, length of anesthesia, and sex. Mortality rate was low (0.33%). We conclude that both isoflurane and sevoflurane anesthesia were effective for field anesthesia to safely handle and sample SSL.
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Field anesthesia of juvenile Steller sea lions (Eumetopias jubatus) using inhalation anesthesia
Marine Mammal Science, 2017Co-Authors: Marianne Lian, Tom Gelatt, Kimberlee B Beckmen, Shawn P. Johnson, Todd M. O'hara, Lorrie D ReaAbstract:Between 1998 and 2008, 621 Steller sea lions (Eumetopias jubatus, SSL) were captured underwater by SCUBA divers and anesthetized with isoflurane (n = 602) or sevoflurane (n = 19). We found significantly faster induction time (X ± SD) for sevoflurane (11 ± 6 min) compared to isoflurane (14 ± 6 min), as well as an interaction between anesthetists using the isoflurane protocol. Severe hypothermia with temperatures
Russel D. Andrews - One of the best experts on this subject based on the ideXlab platform.
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differentiating between steller sea lion Eumetopias jubatus and northern fur seal callorhinus ursinus scats through analysis of faecal dna
Molecular Ecology Resources, 2011Co-Authors: Russel D. Andrews, Jason N Waite, Mary Bozza, Lisette P WaitsAbstract:: We describe a method to determine the species of pinniped from faeces collected from sympatric Steller sea lion (Eumetopias jubatus) and northern fur seal (Callorhinus ursinus) rookeries using newly developed species-specific primers that amplify a 667-669-base pair segment from the mitochondrial DNA (mtDNA) cytochrome B (cytB) gene region. The primers yielded the correct species in 100% of tissue samples from 10 known animals and 100% of faecal samples from 13 known animals. Species could be identified unequivocally for 87.7% of faecal samples from 122 unknown individuals. The ability to differentiate between scats of sympatrically breeding Steller sea lions and northern fur seals will contribute to the range-wide knowledge of the foraging strategies of both species as well as allow researchers to examine the niche partitioning and potential resource competition between the two predators.
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differentiating between steller sea lion Eumetopias jubatus and northern fur seal callorhinus ursinus scats through analysis of faecal dna
Molecular Ecology Resources, 2011Co-Authors: Russel D. Andrews, Jason N Waite, Mary Bozza, Lisette P WaitsAbstract:: We describe a method to determine the species of pinniped from faeces collected from sympatric Steller sea lion (Eumetopias jubatus) and northern fur seal (Callorhinus ursinus) rookeries using newly developed species-specific primers that amplify a 667-669-base pair segment from the mitochondrial DNA (mtDNA) cytochrome B (cytB) gene region. The primers yielded the correct species in 100% of tissue samples from 10 known animals and 100% of faecal samples from 13 known animals. Species could be identified unequivocally for 87.7% of faecal samples from 122 unknown individuals. The ability to differentiate between scats of sympatrically breeding Steller sea lions and northern fur seals will contribute to the range-wide knowledge of the foraging strategies of both species as well as allow researchers to examine the niche partitioning and potential resource competition between the two predators.
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Predicting metabolic rate from heart rate in juvenile Steller sea lions Eumetopias jubatus.
Journal of Experimental Biology, 2003Co-Authors: Jan M. Mcphee, Russel D. Andrews, David A S Rosen, Andrew W. TritesAbstract:SUMMARY The validity of using heart rate to estimate energy expenditure in free-ranging Steller sea lions Eumetopias jubatus was investigated by establishing whether there is a relationship between heart rate (fH) and oxygen consumption rate (VO2) in captive sea lions while swimming and resting. Four trained Steller sea lions (2 males and 2 females; mass 87.4–194.4 kg; age 16 months–3 years) were each equipped with a datalogger and two dorsal subcutaneous electrodes to record electrocardiograms from which fH was calculated. VO2 (measured using open-circuit respirometry) was simultaneously recorded while the previously fasted animals were at rest within an enclosed dry metabolic chamber or while they swam in an enclosed swim mill against water currents of various speeds (0–1.5 m s–1). The mean regression equation describing the relationship between fH (beats min–1) and VO2 (ml h–1 kg–0.60) for all four animals was VO2 =(71.3fH±4.3)–(1138.5±369.6) (means± S.E.M.) (r2=0.69, P
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predicting metabolic rate from heart rate in juvenile steller sea lions Eumetopias jubatus
The Journal of Experimental Biology, 2003Co-Authors: Jan M. Mcphee, Russel D. Andrews, David A S Rosen, Andrew W. TritesAbstract:SUMMARY The validity of using heart rate to estimate energy expenditure in free-ranging Steller sea lions Eumetopias jubatus was investigated by establishing whether there is a relationship between heart rate (fH) and oxygen consumption rate (VO2) in captive sea lions while swimming and resting. Four trained Steller sea lions (2 males and 2 females; mass 87.4–194.4 kg; age 16 months–3 years) were each equipped with a datalogger and two dorsal subcutaneous electrodes to record electrocardiograms from which fH was calculated. VO2 (measured using open-circuit respirometry) was simultaneously recorded while the previously fasted animals were at rest within an enclosed dry metabolic chamber or while they swam in an enclosed swim mill against water currents of various speeds (0–1.5 m s–1). The mean regression equation describing the relationship between fH (beats min–1) and VO2 (ml h–1 kg–0.60) for all four animals was VO2 =(71.3fH±4.3)–(1138.5±369.6) (means± S.E.M.) (r2=0.69, P<0.01). The relationship demonstrated between fH and VO2 while fasting suggests that heart rate can potentially be used to monitor energy consumption in free-ranging Steller sea lions. However, a short-term feeding experiment revealed no significant increase in heart rate following a 6 kg or 12 kg meal to match the observed increase in rate of oxygen consumption. This suggests that heart rate may not accurately reflect energy consumption during digestion events. Additional research should be conducted to further elucidate how the relationship between heart rate and oxygen consumption is affected by such factors as digestive state, stress and age.
Jason N Waite - One of the best experts on this subject based on the ideXlab platform.
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Environmental and biological factors influencing maternal attendance patterns of Steller sea lions (Eumetopias jubatus) in Russia
Journal of Mammalogy, 2011Co-Authors: Vladimir Burkanov, Jason N Waite, Eliezer Gurarie, Alexey Altukhov, Evgeny G. Mamaev, P. A. Permyakov, Alexey M. Trukhin, Tom GelattAbstract:Abstract Maternal attendance patterns in free-ranging wildlife can provide insight into basic biology, foraging behavior, and population dynamics. We collected detailed visual observations of attendance patterns by adult lactating Steller sea lions (Eumetopias jubatus) from 2005 to 2007 on 6 major rookeries in the Russian Far East, including those with an increasing population trend (Sea of Okhotsk), severely depleted populations that were recovering (Kuril Islands), or those that were stable (Commander Islands). Individually identifiable females were observed during the postpartum period, with special attention paid to presence and absence during the day and to departure and arrival times. Within Russia females on several Kuril Islands rookeries exhibited extremely short foraging trip durations (median 6.5–8.0 h) and spent higher proportions of time on the rookery (75–82%), whereas females in the Sea of Okhotsk population had the longest trips (median 19.8 h) and spent the least amount of time on the roo...
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differentiating between steller sea lion Eumetopias jubatus and northern fur seal callorhinus ursinus scats through analysis of faecal dna
Molecular Ecology Resources, 2011Co-Authors: Russel D. Andrews, Jason N Waite, Mary Bozza, Lisette P WaitsAbstract:: We describe a method to determine the species of pinniped from faeces collected from sympatric Steller sea lion (Eumetopias jubatus) and northern fur seal (Callorhinus ursinus) rookeries using newly developed species-specific primers that amplify a 667-669-base pair segment from the mitochondrial DNA (mtDNA) cytochrome B (cytB) gene region. The primers yielded the correct species in 100% of tissue samples from 10 known animals and 100% of faecal samples from 13 known animals. Species could be identified unequivocally for 87.7% of faecal samples from 122 unknown individuals. The ability to differentiate between scats of sympatrically breeding Steller sea lions and northern fur seals will contribute to the range-wide knowledge of the foraging strategies of both species as well as allow researchers to examine the niche partitioning and potential resource competition between the two predators.
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differentiating between steller sea lion Eumetopias jubatus and northern fur seal callorhinus ursinus scats through analysis of faecal dna
Molecular Ecology Resources, 2011Co-Authors: Russel D. Andrews, Jason N Waite, Mary Bozza, Lisette P WaitsAbstract:: We describe a method to determine the species of pinniped from faeces collected from sympatric Steller sea lion (Eumetopias jubatus) and northern fur seal (Callorhinus ursinus) rookeries using newly developed species-specific primers that amplify a 667-669-base pair segment from the mitochondrial DNA (mtDNA) cytochrome B (cytB) gene region. The primers yielded the correct species in 100% of tissue samples from 10 known animals and 100% of faecal samples from 13 known animals. Species could be identified unequivocally for 87.7% of faecal samples from 122 unknown individuals. The ability to differentiate between scats of sympatrically breeding Steller sea lions and northern fur seals will contribute to the range-wide knowledge of the foraging strategies of both species as well as allow researchers to examine the niche partitioning and potential resource competition between the two predators.
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Inter- and intra-researcher variation in measurement of morphometrics on Steller sea lions (Eumetopias jubatus)
Polar Biology, 2009Co-Authors: Jason N Waite, Jo-ann E. MellishAbstract:Substantial effort has been made to increase the accuracy of photogrammetric measurement techniques, especially on marine mammals. However, accuracy of the physical measurements is rarely considered when calculating the photogrammetric accuracy. We examined inter- and intra-researcher variation in the measurement of physical morphometrics of Steller sea lions (Eumetopias jubatus) to assess their potential effects on photogrammetric accuracy and body mass predictions based on photogrammetrically derived morphometrics. Significant differences were found inter-researcher in median standard length and axillary girth and intra-researcher when measuring axillary girth of the same animals. Photogrammetrically derived estimates of these parameters are comparable to physical measurements when taking into account the inherent inter- and intra-researcher variation.
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Three-dimensional photogrammetry as a tool for estimating morphometrics and body mass of Steller sea lions (Eumetopias jubatus)
Canadian Journal of Fisheries and Aquatic Sciences, 2007Co-Authors: Jason N Waite, Jo-ann E. Mellish, Wendy J. Schrader, Markus HorningAbstract:A technique was developed to estimate morphometrics and body mass of Steller sea lions (Eumetopias jubatus) using three-dimensional (3D) photogrammetry. 3D photogrammetry reduces many of the problems associated with camera and body position encountered with two-dimensional photogrammetric techniques, allowing body mass estimation of free-ranging, active sea lions, without sedation, heavy weighing equipment, and disturbance. 3D computer wireframes of 53 Steller sea lions of various age classes were generated from multiple time-synchronous digital photos and used to estimate length, girth, and volume. Average estimates of standard length and axillary girth were within ±2.5% and ±4.0% of physically measured dimensions, respectively. Average estimates of standard length and axillary girth using only wireframes based on ideal body postures were within ±1.7% and ±3.1% of physically measured di- mensions, respectively. Regressions of physically measured mass on photogrammetrically estimated body volume yielded a predictive model. Body mass estimates using this model were on average within 9.0% (95% confidence interval = ±1.7%) of the physically measured mass. This technique was also successfully applied to reptiles and fish. Resume : Nous avons mis au point une technique pour estimer les donnees morphometriques et la masse corporelle chez des lions de mer de Steller (Eumetopias jubatus) a l'aide de la photogrammetrie tridimensionnelle (3D). La
Thomas R. Loughlin - One of the best experts on this subject based on the ideXlab platform.
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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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VARIATION IN MICROSATELLITES AND mtDNA ACROSS THE RANGE OF THE STELLER SEA LION, Eumetopias jubatus
Journal of Mammalogy, 2004Co-Authors: Robert G. Trujillo, John C Patton, Thomas R. Loughlin, Neil J. Gemmell, John W. BickhamAbstract:Abstract Genetic variation at 6 nuclear microsatellite loci with biparental inheritance and the maternally inherited mitochondrial DNA (mtDNA) was studied at 3 geographic scales (rookeries, regions, and stocks) in Steller sea lions (Eumetopias jubatus). Genetic variation was high in both nuclear and mtDNA markers as revealed by a near range-wide survey of 21 rookeries. However, population structure was not well defined, and there was no obvious phylogeographic pattern to the distribution of microsatellite alleles. This contrasts with a clear phylogeographic pattern revealed by control-region sequences of mtDNA in which 2 well-differentiated stocks, eastern and western, are defined as well as 2 distinct groups, Asian and central, in the western stock. Effective migration estimates are consistently higher for the nuclear loci than for mtDNA. The difference in patterns between the biparentally and maternally inherited genetic markers can be explained by relatively high male dispersal rates and female philopa...
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Diving behavior of immature Steller sea lions (Eumetopias jubatus)
2003Co-Authors: Thomas R. Loughlin, John L Sease, Jeremy T. Sterling, Richard L. Merrick, Anne E YorkAbstract:Understanding the ontogenetic relationship between juvenile Steller sea lions (Eumetopias jubatus) and their foraging habitat is key to understanding their relationship to available prey and ultimately their survival. We summarize dive and movement data from 13 young-of-the-year (YOY) and 12 yearling Steller sea lions equipped with satellite dive recorders in the Gulf of Alaska and Aleutian Islands (n=18), and Washington (n=7) from 1994 to 2000. A total of 1413 d of transmission (x =56.5 d, range: 14.5–104.1 d) were received. We recorded 222,073 dives, which had a mean depth of 18.4 m (range of means: 5.8−67.9 m; SD=16.4). Alaska YOY dived for shorter periods and at shallower depths (mean depth=7.7 m, mean duration=0.8 min, mean maximum depth=25.7 m, and maximum depth=252 m) than Alaska yearlings (x =16.6 m, 0=1.1 min, x = 63.4 m, 288 m), whereas Washington yearlings dived the longest and deepest (mean depth=39.4 m, mean duration=1.8 min, mean maximum depth=144.5 m, and maximum depth=328 m). Mean distance for 564 measured trips was 16.6 km; for sea lions ≤10 months of age, trip distance (7.0 km) was significantly less than for those >10 months of age (24.6 km). Mean trip duration for 10 of the 25 sea lions was 12.1 h; for sea lions ≤10 months of age, trip duration was 7.5 h and 18.1 h for those >10 months of age. We identified three movements types: long-range trips (>15 km and >20 h), short-range trips (
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diving behavior of immature steller sea lions Eumetopias jubatus
2003Co-Authors: Thomas R. Loughlin, John L Sease, Jeremy T. Sterling, Richard L. Merrick, Anne E YorkAbstract:Understanding the ontogenetic relationship between juvenile Steller sea lions (Eumetopias jubatus) and their foraging habitat is key to understanding their relationship to available prey and ultimately their survival. We summarize dive and movement data from 13 young-of-the-year (YOY) and 12 yearling Steller sea lions equipped with satellite dive recorders in the Gulf of Alaska and Aleutian Islands (n=18), and Washington (n=7) from 1994 to 2000. A total of 1413 d of transmission (x =56.5 d, range: 14.5–104.1 d) were received. We recorded 222,073 dives, which had a mean depth of 18.4 m (range of means: 5.8−67.9 m; SD=16.4). Alaska YOY dived for shorter periods and at shallower depths (mean depth=7.7 m, mean duration=0.8 min, mean maximum depth=25.7 m, and maximum depth=252 m) than Alaska yearlings (x =16.6 m, 0=1.1 min, x = 63.4 m, 288 m), whereas Washington yearlings dived the longest and deepest (mean depth=39.4 m, mean duration=1.8 min, mean maximum depth=144.5 m, and maximum depth=328 m). Mean distance for 564 measured trips was 16.6 km; for sea lions ≤10 months of age, trip distance (7.0 km) was significantly less than for those >10 months of age (24.6 km). Mean trip duration for 10 of the 25 sea lions was 12.1 h; for sea lions ≤10 months of age, trip duration was 7.5 h and 18.1 h for those >10 months of age. We identified three movements types: long-range trips (>15 km and >20 h), short-range trips (<15 km and <20 h) during which the animals left and returned to the same site, and transits to other haul-out sites. Long-range trips started around 9 months of age and occurred most frequently around the assumed time of weaning, whereas short-range trips happened almost daily (0.9 trips/day, n=426 trips). Transits began as early as 7 months of age, occurred more often after 9 months of age, and ranged between 6.5 and 454 km. The change in dive characteristics coincided with the assumed onset of weaning. These yearling sea lion movement patterns and dive characteristics suggest that immature Steller sea lions are as capable of making the same types of movements as adults.
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DISPERSAL, ROOKERY FIDELITY, AND METAPOPULATION STRUCTURE OF STELLER SEA LIONS (Eumetopias jubatus) IN AN INCREASING AND A DECREASING POPULATION IN ALASKA
Marine Mammal Science, 2002Co-Authors: Kimberly L. Raum-suryan, John L Sease, Kenneth W Pitcher, Donald G. Calkins, Thomas R. LoughlinAbstract:Over the past 24 yr, 8,596 Steller sea lion (Eumetopias jubatus) pups were branded on their natal rookeries throughout Alaska with the objectives of determining survival rates, recruitment, movements, and site fidelity. Our objectives here were to examine the extent of dispersal of Steller sea lions away from their natal rookeries, movements between stocks, and degree of natal rookery fidelity. Pups (
