Sequence variation of a 238 bp segment of the mitochondrial control region was analyzed for 1,568 Steller sea lions (2.8% of the estimated species population) sampled from 50 rookeries representing nearly every locality at which Steller sea lions are known to breed in significant numbers. Haplotype diversity (H = 0.9164 ± 0.0035) was high and nucleotide diversity (π = 0.00967 ± 0.00586) was moderate. No evidence was observed for significant genetic bottleneck effects. Rookeries were grouped into regions and stocks to examine structure at different spatial scales. F- and Φ-statistics were computed for all pairwise comparisons of rookeries, regions and stocks. Significant (P<0.05) divergence of eastern stock (southeastern Alaska to California) animals from western stock animals was supported in analyses at all spatial scales. Likewise, rookeries and regions from Asia were found to be significantly different from all other western stock rookeries. This was most clearly demonstrated using Φ-statistics at the regional level. The Commander Islands clearly associate with Alaskan western stock rookeries, not with the Asian rookeries. Within each of the three stocks there is significant isolation by distance among rookeries. This relationship does not hold for inter-stock comparisons indicating that there are important barriers to gene flow among stocks. Mitochondrial DNA analysis supports the recognition of three stocks for appropriate conservation of the species. The currently recognized eastern stock is unaffected, but the western stock is now partitioned west of the Commander Islands yielding a western stock which ranges from Prince William Sound west to the Commander Islands, and an Asian stock including rookeries from the Kamchatka Peninsula, Kuril Islands, and Sea of Okhtosk.

Recent studies indicate a 70% decrease in the Alaskan Steller sea lion (SSL) population (ca. 5% per year) since the early 1980's. In accordance with a 1997 status classification of the Western Steller sea lion (WSSL) stock as endangered, the "critical habitat" for the species was to be defined. This habitat has now been designated to include 10-20 nautical mile buffer zones around most rookeries and haulouts in the Gulf of Alaska (GOA) and Aleutian Islands. However, these zones were based on limited, summer, foraging data. The primary objective of this study was to characterize juvenile SSL diving behavior and habitat use along the Kenai Peninsula and Prince William Sound (PWS) from winter to spring. Fifteen free ranging, subadult SSL of both sexes were captured and equipped with satellite telemeters at five haulout sites in PWS and Resurrection Bay, Alaska. Telemeters transmitted for an average of 122 days (range 38-181 days). A total of 11,692 locations were received and 217,419 dives recorded. All sea lions exhibited localized movements parallel or close to shore (3-15 km offshore). Young of the year (YOY) exhibited high site fidelity. Older juvenile sea lion lions were less restricted in their movements and traveled greater distances (200-400km) visiting a variety of islands, buoys, and other locations in PWS. Most dives were short (mean duration = 1.1 min) and shallow (mean depth = 10.8 m), with animals diving to an average maximum depth of 193 m. During winter (January and February), many dives (>40%) occurred during the daytime (0900-1500 LT). However, by April and May this pattern shifted and the animals made most of their dives (>40%) during the night (2100-0300 LT). This relationship was more pronounced for dives deeper than 20 m and coincided with the seasonal increase in photoperiod. Subadult SSL, especially YOY, remained within the 20 nautical mile coastal zone during winter and spring. Shallow, nearshore waters provide important habitat during this critical period of transition to nutritional independence. However, more conclusive data on SSL foraging ecology is necessary to better understand locations and depths preferred by the species.

Sequence variation of a 238 bp segment of the mitochondrial control region was analyzed for 1,568 Steller sea lions (2.8% of the estimated species population) sampled from 50 rookeries representing nearly every locality at which Steller sea lions are known to breed in significant numbers. Haplotype diversity (H = 0.9164 ± 0.0035) was high and nucleotide diversity (π = 0.00967 ± 0.00586) was moderate. No evidence was observed for significant genetic bottleneck effects. Rookeries were grouped into regions and stocks to examine structure at different spatial scales. F- and Φ-statistics were computed for all pairwise comparisons of rookeries, regions and stocks. Significant (P<0.05) divergence of eastern stock (southeastern Alaska to California) animals from western stock animals was supported in analyses at all spatial scales. Likewise, rookeries and regions from Asia were found to be significantly different from all other western stock rookeries. This was most clearly demonstrated using Φ-statistics at the regional level. The Commander Islands clearly associate with Alaskan western stock rookeries, not with the Asian rookeries. Within each of the three stocks there is significant isolation by distance among rookeries. This relationship does not hold for inter-stock comparisons indicating that there are important barriers to gene flow among stocks. Mitochondrial DNA analysis supports the recognition of three stocks for appropriate conservation of the species. The currently recognized eastern stock is unaffected, but the western stock is now partitioned west of the Commander Islands yielding a western stock which ranges from Prince William Sound west to the Commander Islands, and an Asian stock including rookeries from the Kamchatka Peninsula, Kuril Islands, and Sea of Okhtosk.

Steller sea lions, the largest Otariid, fast during their breeding season; during this time they refrain from ingesting food for a period of 12-43 days. Fasting, while undertaking an extremely energetically demanding activity (breeding and pupping), requires specific physiological adaptations. This study examined the physiological response to fasting of two age classes, juveniles and sub-adults, during the breeding and non-breeding seasons to determine how these animals utilize lipids and the pattern of fatty acid mobilization from lipid stores during fasting. Four juveniles and 5 sub-adults were fasted for one and two weeks, respectively, and blood samples were collected approximately every 3 days for lipid analysis. The concentrations of plasma non-esterified fatty acids (NEFA) were analyzed spectrophotometrically. Serum fatty acid composition was analyzed using gas chromatography (GC) and their individual weight percent (wt %) were correlated with their peak retention time and calculated using the area under each peak. Sixty-nine fatty acids were quantified from each sample. However, only those with concentrations above 0.2 wt. % were included in the analysis. Sub-adult samples were grouped on a percent mass loss basis (0%, 7-8% and 15% mass loss) to facilitate comparison with the juveniles. These data represent the total lipid fatty acid composition of each blood sample. Relative lipid concentration was calculated by multiplying the total lipid fatty acid compositional analysis (wt %) by the NEFA concentrations measured in that respective blood sample. Plasma NEFA concentrations in juvenile Steller sea lions ranged from 1.2 [plus or minus] 0.51 mM to 3.7 [plus or minus] 0.69 during fasting and was within the range of fasting phocids. Concentrations of NEFAs in the sub-adult Steller sea lions ranged from 1.00 mM up to 9.70 mM and were generally higher than fasting phocids. The wt % of only one fatty acid (20:0) was significantly different between the breeding and non-breeding season in fasting juveniles. However, the wt % of seven fatty acids changed significantly during fasting in the juveniles and five of these were most significant in separating the beginning and end of the fasts using principal components analysis. In contrast, the wt % of 10 fatty acids were significantly different during the breeding and non-breeding season fasts of the sub-adults. Additionally, the wt % of 10 fatty acids changed significantly during fasting in the sub-adults and four of these (16:1n-7, 18:2n-6, 20:0, and 20:1n-9) were most significant in separating the beginning and end of the fasts using principal components analysis. These trends reveal the physiological differences between the juvenile and sub-adult Steller sea lions and suggest that the sub-adults may be better physiologically and metabolically adapted to fast than the juveniles in this study.

Maintaining thermal balance is essential for all homeotherms but can be especially challenging for pinnipeds which must regulate over a variety of ambient temperatures and habitats as part of their life history. Young pinnipeds, with their immature physiology and inexperience, have the additional expense of needing to allocate energy for growth while still dealing with a thermally stressful aquatic environment. With the immense environmental and physiological pressures acting on juvenile age-classes, declines in prey resources would be particularly detrimental to survival. The goal of the present study was to examine the metabolic and thermoregulatory capabilities of juvenile Steller sea lions to better understand how changing prey resources indirectly impact juvenile age classes. Data collected from captive Steller sea lions suggest that changes in body mass and body composition influence the thermoregulatory capabilities of smaller sea lions in stationary and flowing water. Serial thermal images taken of sea lions after emergence from the water show vasoconstriction of the flippers compared to the body trunk to help minimize heat loss. Despite this ability to vasoconstrict, sea lions in poor body condition displayed a reduced tolerance for colder water temperatures, suggesting that decreases in prey availability which affect insulation may limit survival in younger sea lions. If reductions in prey availability (i.e., nutritional stress) were impacting western Alaskan populations, a reduction in energetic expenditures would be expected in these animals to cope. Measures of resting metabolism in juvenile free-ranging Steller sea lions across Alaska showed no differences between eastern and western capture locations, suggesting no evidence of metabolic depression in declining western stocks of sea lions. Finally, thermal costs predicted by a thermal balance model were compared to actual costs measured in the present study. Model output reliably predicted thermoregulatory costs for juvenile Steller sea lions under certain environmental conditions. Basic physiological measurements combined with the predictive power of modeling will allow for greater exploration of the environmental constraints on juvenile Steller sea lions and identify directions of future study.

Maintaining thermal balance is essential for all homeotherms but can be especially challenging for pinnipeds which must regulate over a variety of ambient temperatures and habitats as part of their life history. Young pinnipeds, with their immature physiology and inexperience, have the additional expense of needing to allocate energy for growth while still dealing with a thermally stressful aquatic environment. With the immense environmental and physiological pressures acting on juvenile age-classes, declines in prey resources would be particularly detrimental to survival. The goal of the present study was to examine the metabolic and thermoregulatory capabilities of juvenile Steller sea lions to better understand how changing prey resources indirectly impact juvenile age classes. Data collected from captive Steller sea lions suggest that changes in body mass and body composition influence the thermoregulatory capabilities of smaller sea lions in stationary and flowing water. Serial thermal images taken of sea lions after emergence from the water show vasoconstriction of the flippers compared to the body trunk to help minimize heat loss. Despite this ability to vasoconstrict, sea lions in poor body condition displayed a reduced tolerance for colder water temperatures, suggesting that decreases in prey availability which affect insulation may limit survival in younger sea lions. If reductions in prey availability (i.e., nutritional stress) were impacting western Alaskan populations, a reduction in energetic expenditures would be expected in these animals to cope. Measures of resting metabolism in juvenile free-ranging Steller sea lions across Alaska showed no differences between eastern and western capture locations, suggesting no evidence of metabolic depression in declining western stocks of sea lions. Finally, thermal costs predicted by a thermal balance model were compared to actual costs measured in the present study. Model output reliably predicted thermoregulatory costs for juvenile Steller sea lions under certain environmental conditions. Basic physiological measurements combined with the predictive power of modeling will allow for greater exploration of the environmental constraints on juvenile Steller sea lions and identify directions of future study.

The coastal, indigenous communities around Alaska have subsisted on marine animals for generations, often focusing on large apex predators such as seals, sea lions, and whales. Three species of pinnipeds (harbor seal, Steller sea lion, northern fur seal) and the northern sea otter have all undergone significant population declines since the 1970s, some regions more than others. Archived vibrissae (whiskers) and body tissues from these four species were available from the Bering Sea and throughout the Gulf of Alaska from the 1990s and early 2000s. Tissues from these species are exceedingly difficult to obtain; thus, the archived tissues provided a finite and irreplaceable resource of data. Analysis of these archived tissues indicates which species, tissues, and gender bioaccumulate metals more readily. In this study twelve heavy metals (arsenic, cadmium, chromium, cobalt, copper, lead, manganese, mercury, nickel, selenium, vanadium, zinc) were analyzed in vibrissae from the four select species, and in body tissues from harbor seals and Steller sea lions. The samples were collected from three regions (southeastern, southcentral, and southwestern Alaska) during the 1990s through early 2000s. Significant differences of heavy metal concentrations in vibrissae were detected among elements (p2(110) = 454.81, p2(66) = 310.88, p

Range, areas of concentrated activity, and dispersal characteristics for juvenile Steller sea lions Eumetopias jubatus in the endangered western population (west of 144° W in the Gulf of Alaska) are poorly understood. This study quantified space use by analyzing post-release telemetric tracking data from satellite transmitters externally attached to n = 65 juvenile (12-25 months; 72.5 to 197.6 kg) Steller sea lions (SSLs) captured in Prince William Sound (60°38'N -147°8'W) or Resurrection Bay (60°2'N -149°22'W), Alaska, from 2003-2011. The analysis divided the sample population into 3 separate groups to quantify differences in distribution and movement. These groups included sex, the season when collected, and the release type (free ranging animals which were released immediately at the site of capture, and transient juveniles which were kept in captivity for up to 12 weeks as part of a larger ongoing research program). Range-use was first estimated by using the minimum convex polygon (MCP) approach, and then followed with a probabilistic kernel density estimation (KDE) to evaluate both individual and group utilization distributions (UDs). The LCV method was chosen as the smoothing algorithm for the KDE analysis as it provided biologically meaningful results pertaining to areas of concentrated activity (generally, haulout locations). The average distance traveled by study juveniles was 2,131 ± 424 km. The animals mass at release (F[subscript 1, 63] = 1.17, p = 0.28) and age (F[subscript 1, 63] = 0.033, p = 0.86) were not significant predictors of travel distance. Initial MCP results indicated the total area encompassed by all study SSLs was 92,017 km², excluding land mass. This area was heavily influenced by the only individual that crossed over the 144°W Meridian, the dividing line between the two distinct population segments. Without this individual, the remainder of the population (n = 64) fell into an area of 58,898 km². The MCP area was highly variable, with a geometric average of 1,623.6 km². Only the groups differentiated by season displayed any significant difference in area size, with the Spring/Summer (SS) groups MCP area (Mdn = 869.7 km²) being significantly less than that of the Fall/Winter (FW) group (Mdn = 3,202.2 km²), U = 330, p = 0.012, r = -0.31. This result was not related to the length of time the tag transmitted (H(2) = 49.65, p = 0.527), nor to the number of location fixes (H(2) = 62.77, p = 0.449). The KDE UD was less variable, with 50% of the population within a range of 324-1,387 km2 (mean=690.6 km²). There were no significant differences in area use associated with sex or release type (seasonally adjusted U = 124, p = 0.205, r = -0.16 and U = 87, p = 0.285, r = -0.13, respectively). However, there were significant differences in seasonal area use: U = 328, p = 0.011, r = -0.31. There was no relationship between the UD area and the amount of time the tag remained deployed (H(2) = 45.30, p = 0.698). The kernel home range (defined as 95% of space use) represented about 52.1% of the MCP range use, with areas designated as "core" (areas where the sea lions spent fully 50% of their time) making up only about 6.27% of the entire MCP range and about 11.8% of the entire kernel home range. Area use was relatively limited – at the population level, there were a total of 6 core areas which comprised 479 km². Core areas spanned a distance of less than 200 km from the most western point at the Chiswell Islands (59°35'N -149°36'W) to the most eastern point at Glacier Island (60°54'N -147°6'W). The observed differences in area use between seasons suggest a disparity in how juvenile SSLs utilize space and distribute themselves over the course of the year. Due to their age, this variation is less likely due to reproductive considerations and may reflect localized depletion of prey near preferred haul-out sites and/or changes in predation risk. Currently, management of the endangered western and threatened eastern population segments of the Steller sea lion are largely based on population trends derived from aerial survey counts and terrestrial-based count data. The likelihood of individuals to be detected during aerial surveys, and resulting correction factors to calculate overall population size from counts of hauled-out animals remain unknown. A kernel density estimation (KDE) analysis was performed to delineate boundaries around surveyed haulout locations within Prince William Sound-Kenai Fjords (PWS-KF). To closely approximate the time in which population abundance counts are conducted, only sea lions tracked during the spring/summer (SS) months (May 10-August 10) were chosen (n = 35). A multiple state model was constructed treating the satellite location data, if it fell within a specified spatiotemporal context, as a re-encounter within a mark-recapture framework. Information to determine a dry state was obtained from the tags time-at-depth (TAD) histograms. To generate an overall terrestrial detection probability 1) The animal must have been within a KDE derived core-area that coincided with a surveyed haulout site 2) it must have been dry and 3) it must have provided at least one position during the summer months, from roughly 11:00 AM-5:00 PM AKDT. A total of 10 transition states were selected from the data. Nine states corresponded to specific surveyed land locations, with the 10th, an "at-sea" location (> 3 km from land) included as a proxy for foraging behavior. A MLogit constraint was used to aid interpretation of the multi-modal likelihood surface, and a systematic model selection process employed as outlined by Lebreton & Pradel (2002). At the individual level, the juveniles released in the spring/summer months (n = 35) had 85.3% of the surveyed haulouts within PWS-KF encompass KDE-derived core areas (defined as 50% of space use). There was no difference in the number of surveyed haulouts encompassed by core areas between sexes (F[subscript 1, 33] << 0.001, p = 0.98). For animals held captive for up to 12 weeks, 33.3% returned to the original capture site. The majority of encounter probabilities (p) fell between 0.42 and 0.78 for the selected haulouts within PWS, with the exceptions being Grotto Island and Aialik Cape, which were lower (between 0.00-0.17). The at-sea (foraging) encounter probability was 0.66 (± 1 S.E. range 0.55-0.77). Most dry state probabilities fell between 0.08-0.38, with Glacier Island higher at 0.52, ± 1 S.E. range 0.49-0.55. The combined detection probability for hauled-out animals (the product of at haul-out and dry state probabilities), fell mostly between 0.08-0.28, with a distinct group (which included Grotto Island, Aialik Cape, and Procession Rocks) having values that averaged 0.01, with a cumulative range of ≈ 0.00-0.02 (± 1 S.E.). Due to gaps present within the mark-recapture data, it was not possible to run a goodness-of-fit test to validate model fit. Therefore, actual errors probably slightly exceed the reported standard errors and provide an approximation of uncertainties. Overall, the combined detection probabilities represent an effort to combine satellite location and wet-dry state telemetry and a kernel density analysis to quantify the terrestrial detection probability of a marine mammal within a multistate modeling framework, with the ultimate goal of developing a correction factor to account for haulout behavior at each of the surveyed locations included in the study. / Graduation date: 2013

Muscle samples from 105 marine mammals stranded along the Oregon-Washington coasts (2002-2009) were tested for levels of total mercury by Cold Vapor Atomic Fluorescence Spectrometry. The total mercury present is predominantly in the form of highly toxic methylmercury. After normalizing muscle tissue to 75% water weight, due to variance in water content, Steller sea lions (Eumetopias jubatus) and northern elephant seals (Mirounga angustirostris) exhibited the highest mean concentrations of total mercury followed by harbor seals (Phoca vitulina), harbor porpoises (Phocoena phocoena), and California sea lions (Zalophus californianus); 0.34 ± 0.278, 0.34 ± 0.485, 0.21 ± 0.216, 0.17 ± 0.169 and 0.15 ± 0.126 mg/kg normalized weight, respectively. Mean normalized values demonstrated limited muscle methylmercury accumulation in these species in the Pacific Northwest. Normalizing muscle mercury concentrations eliminated variability from desiccation, and allowed for a clearer indication of the amount of mercury the animal accumulated before stranding. However, actual wet weight concentrations in some of the stranded carcasses were high enough to pose a risk to scavengers.