Eumetopias Research Articles

Wanted dead or alive: characterizing likelihood of juvenile Steller sea lion predation from diving and space use patterns

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 40:357-367 (2019) - DOI: https://doi.org/10.3354/esr00999 ESR Special: Biologging in conservation Wanted dead or alive: characterizing likelihood of juvenile Steller sea lion predation from diving and space use patterns Amanda M. Bishop1,*, Alexandra K. Dubel2, Renae Sattler3, Casey L. Brown4, Markus Horning1 1Alaska SeaLife Center, Seward, AK 99664, USA 2Florida State University, Tallahassee, FL 32306, USA 3Alaska Department of Fish and Game, Palmer, AK 99645, USA 4Oregon Department of Fish and Wildlife, La Grande, OR 97850, USA *Corresponding author: amybi@alaskasealife.org ABSTRACT: Understanding linkages between behaviors and mortality risk is critical for managing populations. Juveniles constitute a particularly vulnerable life stage, with growing evidence that within stages, individual strategies may be associated with greater predation risk and mortality. These forms of predator-prey dynamics are rarely explored in marine environments due to difficulties in confirming vital status of individuals, and the lack of data sets that link mortality to behavior. We analyzed 2 concurrently collected data sets for juvenile Steller sea lions Eumetopias jubatus in the Gulf of Alaska to examine associations between mortality and specific behavioral patterns. Forty-five juvenile Steller sea lions were instrumented with external satellite tags and internally implanted vital rate transmitters (LHX tags). From 2005 through 2018, 25 juveniles remained alive and 20 died (18 confirmed predation). Using a binomial generalized linear mixed-effects model, we tested whether the probability of individual mortality was associated with seasonally specific dive patterns (time wet, dive depth) or horizontal movement patterns (home range size, average trip distance). Additionally, in 3 cases, external tags were transmitting until death. To examine links between fine-scale ante-mortem behavioral patterns and predation susceptibility, we compared dive patterns recorded during the last 3 d of data transmissions (both for animals which survived and for those which died) to dive patterns recorded during other periods at sea. Results suggest individuals that spent more time dry or dove shallower had a greater mortality probability, which could reflect foraging tactics of predators. This study highlights the effectiveness of combining multiple telemetry systems for exploring the vulnerability of individuals to the consumptive effects of predators. KEY WORDS: Predation · Bio-logging · Diving behavior · Eumetopias jubatus · Risk · Marine mammal Full text in pdf format Supplementary material PreviousNextCite this article as: Bishop AM, Dubel AK, Sattler R, Brown CL, Horning M (2019) Wanted dead or alive: characterizing likelihood of juvenile Steller sea lion predation from diving and space use patterns. Endang Species Res 40:357-367. https://doi.org/10.3354/esr00999 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 40. Online publication date: December 19, 2019 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2019 Inter-Research.

Higher Aggregation of Key Prey Species Associated with Diet and Abundance of the Steller Sea Lion Eumetopias jubatus across the Aleutian Islands

AbstractThe Aleutian Islands ecosystem is a highly dynamic marine environment that supports commercially important fish species, such as Atka Mackerel Pleurogrammus monopterygius and Northern Rockfish Sebastes polyspinis, and several large marine mammals, including the Steller sea lion (SSL) Eumetopias jubatus. To protect SSL foraging behavior and prey, trawl exclusion zones (TEZs) were established around SSL rookeries and haulouts across the Aleutian Islands and are closed to bottom trawling. The Atka Mackerel fishery is concentrated at small, local patches (~37.04 km [~20 nautical miles]) across the Aleutian Islands, often near and adjacent to TEZs. Food web models and fishery stock assessments predict sufficient prey for both the fishery and foraging SSLs at the level of large management areas (each area is ~463 km [~250 nautical miles] longitudinally), but little is known about local fish distribution (~37.04 km) in proximity to SSL rookeries and haulouts. We used CPUE to examine the spatial distribution of two SSL prey species (Atka Mackerel and Northern Rockfish) and marine invertebrates (as a proxy for habitat quality) at large (across the Aleutian Islands) and small (~37.04‐km) scales. Although Atka Mackerel abundance estimates were similar across the Aleutian Islands, the density of Atka Mackerel differed. In the eastern Aleutian Islands, where SSL population trends have stabilized, Atka Mackerel aggregations were dense. In contrast, in the far western Aleutian Islands, where SSL populations are still in decline, Atka Mackerel distributions were diffuse and Northern Rockfish exhibited a greater density. Results indicated no significant difference in CPUE between areas open to fishing and closed areas (i.e., TEZs) at all study sites for Atka Mackerel and at all but one study site for Northern Rockfish, whereas invertebrate densities were significantly higher inside of TEZs at all study sites. We discuss how fish distributions across the Aleutian Islands may impact the success and behavior of foraging SSLs.

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

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

Time‐varying effect of sea ice on the population dynamics of Steller sea lions (Eumetopias jubatus) on Tuleny Island

AbstractThe population of Steller sea lions (SSLs) on Tuleny Island has been increasing continuously since the 1980s. However, the reasons for this increase have remained unknown. In this study, we investigated whether changes in sea ice distribution affected population dynamics on Tuleny Island by applying a Gompertz density‐dependent model in a state‐space framework with a time‐varying coefficient. We compared results from the time‐varying coefficient model with those from two other models that assumed time‐constant effects and no effect of sea ice. For both SSL pups and non‐pups, only the time‐varying coefficient model predicted a significant effect from the timing of sea ice breakup. The SSL population was larger when the sea ice broke up earlier. The sea ice effect was larger at the start of the study period and became insignificant in the late 1980s. Thus, our results suggest that the increase in SSL population on Tuleny Island during the first 20 years could be partly explained by earlier sea ice breakup, which promoted immigration from other rookeries. Because SSLs exhibit strong site‐fidelity as the habituation effect, individuals that visited once may have repeatedly returned to visit and breed on the island, regardless of the sea ice conditions in later years. This may explain why the sea ice effect was only significant in the first years of population increase. Negative density dependence was also only predicted by the time‐varying coefficient model. Adding the time‐varying coefficient to modeling analysis could simultaneously improve predictions of environmental effects and estimations of density dependence.

Links between muscle phenotype and life history: differentiation of myosin heavy chain composition and muscle biochemistry in precocial and altricial pinniped pups.

In marine mammals, muscular development has been identified as a rate-limiting factor in achieving adult dive capacities. This study investigates the rate that myosin heavy chain (MHC) composition matures in a postural and locomotor skeletal muscle for four pinniped species with different lactation lengths: hooded seals, Cystophora cristata; harp seals, Pagophilus groenlandicus; northern fur seals, Callorhinus ursinus, and Steller sea lions, Eumetopias jubatus. The ontogeny of MHC isoform expression was compared with developmental rates of myoglobin concentrations, and aerobic (citrate synthase, β-hydroxyacyl-CoA dehydrogenase) and anaerobic (lactate dehydrogenase) enzyme activities. Within taxonomic families, species with shorter lactation periods had more mature muscles biochemically at birth, and fiber types differentiated earlier during ontogeny (Phocidae: hooded > harp seals, Otariidae: northern fur seals > Steller sea lions). Northern fur seal neonates had the most phenotypically-mature muscles in this study, with no immature MHC isoforms. The relationship between muscle biochemistry and MHC composition became more pronounced with age, and developed to reflect swimming mode and activity levels. In adults, phocids had more slow-twitch oxidative protein in their primary locomotor muscle, the Longissimus dorsi (LD), than otariids which likely reflects oxygen-sparing strategies for the phocids' longer dives. Conversely, northern fur seal muscles had higher proportions of fast-twitch MHCs in the Pectoralis and LD, likely indicative of this species' smaller size and higher mass-specific metabolic rates. Thus, muscle phenotype is linked with species life history, and a mismatch between muscle biochemistry and MHC composition at weaning has important implications for the first year of independent foraging in pinniped pups.

Organochlorine contaminant concentrations in blubber of young Steller sea lion (Eumetopias jubatus) are influenced by region, age, sex, and lipid stores

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.

The Langevin diffusion as a continuous‐time model of animal movement and habitat selection

Abstract The utilization distribution of an animal describes the relative probability of space use. It is natural to think of it as the long‐term consequence of the animal's short‐term movement decisions: it is the accumulation of small displacements which, over time, gives rise to global patterns of space use. However, many estimation methods for the utilization distribution either assume the independence of observed locations and ignore the underlying movement (e.g. kernel density estimation), or are based on simple Brownian motion movement rules (e.g. Brownian bridges). We introduce a new continuous‐time model of animal movement, based on the Langevin diffusion. This stochastic process has an explicit stationary distribution, conceptually analogous to the idea of the utilization distribution, and thus provides an intuitive framework to integrate movement and space use. We model the stationary (utilization) distribution with a resource selection function to link the movement to spatial covariates, and allow inference about habitat preferences of animals. Standard approximation techniques can be used to derive the pseudo‐likelihood of the Langevin diffusion movement model, and to estimate habitat preference and movement parameters from tracking data. We investigate the performance of the method on simulated data, and discuss its sensitivity to the time scale of the sampling. We present an example of its application to tracking data of Steller sea lions Eumetopias jubatus. Due to its continuous‐time formulation, this method can be applied to irregular telemetry data. The movement model is specified using a habitat‐dependent utilization distribution, and it provides a rigorous framework to estimate long‐term habitat selection from correlated movement data. The Langevin movement model can be written as a linear model, which allows for very fast inference. Standard tools such as residuals can be used for model checking.

Kleptoparasitism of the sea otter (Enhydra lutris) and Steller sea lion (Eumetopias jubatus) by the glaucous-winged gull (Larus glaucescens) at Seward, Alaska

Observations of seabirds stealing food (kleptoparasitism) from marine mammals are rarely reported. During 67 h of observation at Seward, Alaska, where fishers frequently discard scraps of fish, we documented 16 incidents of gulls attempting to kleptoparasitize sea otters (Enhydra lutris) and seven incidents of gulls attempting to kleptoparasitize Steller sea lions (Eumetopias jubatus). An average of 3.5 ± 3.5 SD (range 1–13) glaucous-winged gulls (Larus glaucescens) and < 0.1 ± 0.3 SD (range 0–1) black-legged kittiwakes (Rissa tridactyla) attacked sea otters with discarded fish scraps, with a success rate of 53% per incident and 16% per individual gull. The gulls ignored sea otters with invertebrate prey. An average of 3.6 ± 1.7 SD (range 1–7) glaucous-winged gulls and 0.1 ± 0.4 SD (range 0–1) black-legged kittiwakes attacked sea lions with discarded fish scraps, with a success rate of 29% per incident and 8% per individual gull. Only glaucous-winged gulls succeeded in stealing food, usually comprising fragments of the original item floating on the surface after the victim dived, but twice food was stolen directly from sea otters. To avoid kleptoparasitism, sea otters used five evasive maneuvers (swimming away, diving, rolling, lunging toward gull, and pulling food from gull), whereas sea lions used only two (swimming away and diving). Kleptoparasitism of sea otters and sea lions by gulls is a previously overlooked behavior that merits further study of its potential benefits and costs.

MODERN VIEWS ON THE CIRCULATION OF HERPES VIRUSES IN THE OKHOTSK SEA STELLER SEA LION (EUMETOPIAS JUBATUS, SCHREBER, 1776)

Aim. To evaluate the possibility of herpes viruses circulation and possible routes of transmission in population of Steller sea lions of the Sea of Okhotsk by combining a thorough literature study with screening of blood sera samples of Steller sea lion puppies of the Sea of Okhotsk obtained in 2008‐2012.Methods. We investigated 370 blood sera of puppies of the Steller sea lion (2008‐2012) from Tyulenij island, Chkalova island and from the Kurile Islands for the presence of antibodies to two members of the subfamily Alphaherpesvirinae and Gam‐ maherpesvirinae using enzyme‐linked immunosorbent assay (ELISA).Results. The data showed that out of 370 sera samples, 50 contained antibodies to the varicella‐zoster virus (subfamily Alphaherpesvirinae) and 46 – to the Epstein‐Barr virus (subfamily Gammaherpesvirinae).Main conclusions. The literature study revealed that the ecology peculiarities of species contribute to the realization of the main ways of transmission of herpes viruses between individuals. We were also able to identify possible risk factors for the transmission of non‐specific herpes viruses between Steller sea lion and the animals with which they are forced to coexist. The results obtained are in a good agreement with the literature data and indirectly confirm the circulation of herpes viruses in the Steller sea lion of the Kuril Islands, as well as the island Tyulenij. We observe a significant difference in the number of Steller sea lion puppies with the presence of antibodies to gamma‐herpes viruses on the Kuril Islands and the Okhotsk Sea is‐ lands (Р &gt; 99,7). Differences in the number of Steller sea lion puppies with the presence of anti‐ bodies to alpha herpes viruses were not reliably detected.

The Genome of the Steller Sea Lion (Eumetopias jubatus).

The Steller sea lion is the largest member of the Otariidae family and is found in the coastal waters of the northern Pacific Rim. Here, we present the Steller sea lion genome, determined through DNA sequencing approaches that utilized microfluidic partitioning library construction, as well as nanopore technologies. These methods constructed a highly contiguous assembly with a scaffold N50 length of over 14 megabases, a contig N50 length of over 242 kilobases and a total length of 2.404 gigabases. As a measure of completeness, 95.1% of 4104 highly conserved mammalian genes were found to be complete within the assembly. Further annotation identified 19,668 protein coding genes. The assembled genome sequence and underlying sequence data can be found at the National Center for Biotechnology Information (NCBI) under the BioProject accession number PRJNA475770.

Aging steller sea lions by growth layer groups in teeth

ABSTRACTAccurate age determination of individuals is crucial in estimating age structure in populations as well as age‐specific rates of reproduction and survival. We examined growth layer groups (GLGs) in the canine, incisor, and postcanine teeth of Steller sea lions (Eumetopias jubatus) to find the optimal method to determine their age using 18 known‐age animals, from data collected in Hokkaido, Japan, 1995–2011. After checking to determine if the pulp cavity was open, nearly closed, or closed, teeth were sectioned and stained. Occlusion of the canine pulp cavity occurred at older ages than with the incisor and postcanine teeth. Initially, the number of GLGs in both dentin and cementum was compared with actual ages to confirm the age determination method. Dentin GLGs appeared clearly in all of the canines, incisors, and postcanines. The number of GLGs was consistent with the actual age, with the exception of teeth with a closed pulp cavity. With respect to cementum, appearance of GLGs was rather obscure and no GLG was detectable at ages of 0 and 1 year. Thus, the number of GLGs in cementum could be assigned as age when the value 1 year was added. We examined the accuracy and precision of the tested methods using an independent reader, who did not know the actual ages. By conducting readings 3 times, we used coefficient of variation (CV) to determine precision. The most precise CV was obtained in dentin canine (6.7%). Accuracy was calculated as proportion of estimates without error. The greatest accuracy in dentin was observed in canines (0.83, n = 18), whereas that of cementum was in postcanines (0.36, n = 11). We concluded that canine dentin provided the most precise and accurate ages for Steller sea lions. Once closure of the pulp cavity in canines has occurred at the age of 15–16 years in males and 11–12 years in females, we recommend postcanine cementum be used. © 2019 The Wildlife Society.

Dental integration and modularity in pinnipeds

Morphological integration and modularity are important for understanding phenotypic evolution because they constrain variation subjected to selection and enable independent evolution of functional and developmental units. We report dental integration and modularity in representative otariid (Eumetopias jubatus, Callorhinus ursinus) and phocid (Phoca largha, Histriophoca fasciata) species of Pinnipedia. This is the first study of integration and modularity in a secondarily simplified dentition with simple occlusion. Integration was stronger in both otariid species than in either phocid species and related positively to dental occlusion and negatively to both modularity and tooth-size variability across all the species. The canines and third upper incisor were most strongly integrated, comprising a module that likely serves as occlusal guides for the postcanines. There was no or weak modularity among tooth classes. The reported integration is stronger than or similar to that in mammals with complex dentition and refined occlusion. We hypothesise that this strong integration is driven by dental occlusion, and that it is enabled by reduction of modularity that constrains overall integration in complex dentitions. We propose that modularity was reduced in pinnipeds during the transition to aquatic life in association with the origin of pierce-feeding and loss of mastication caused by underwater feeding.

The diet of free-ranging male Steller sea lions (Eumetopias jubatus) in the eastern Bering Sea: a retrospective analysis based on stomach contents of an endangered pinniped

This study illuminates historical diet and foraging locations of endangered western U.S. stock Steller sea lions (Eumetopias jubatus (Schreber, 1776)). Prey were identified from stomachs of 22 males collected in the eastern Bering Sea from the ice edge in March 1985 and nearshore St. Paul Island in September–October 1985 and 1986. Percent frequency of occurrence (PFO) and percent number (PN) were highest for walleye pollock (Gadus chalcogrammus Pallas, 1814; PFO 69%, PN 15%, mean length 17 cm), Pacific herring (Clupea pallasii Valenciennes in Cuvier and Valenciennes, 1847; PFO 62%, PN 16%, mean length 26 cm), shorthorn sculpin (Myoxocephalus scorpius (Linnaeus, 1758); PFO 54%, PN 30%), and Pacific giant octopus (Enteroctopus dofleini (Wülker, 1910); PFO 39%, PN 8%, mean weight 31 kg) in spring, and northern rock sole (Lepidopsetta polyxystra Orr and Matarese, 2000; PFO 78%, PN 47%, mean length 35 cm), Pacific cod (Gadus macrocephalus Tilesius, 1810; PFO 56%, PN 12%, mean length 62 cm), walleye pollock (PFO 44%, PN 7%, mean length 49 cm), and red Irish lord (Hemilepidotus hemilepidotus (Tilesius, 1811); PFO 11%, PN 9%) in fall. Species of Cryptacanthidae, Liparidae, and Zoarcidae were highly represented and exclusive to spring collections. Predictable seasonal concentrations and movements of mature prey along frontal boundaries of the continental shelf and ice edge may be critical to male Steller sea lion fitness during the non-breeding season.

Use of a Sendai virus-based vector for effcient transduction of pinniped fbroblasts

Generation of induced pluripotent stem (iPS) cells expanded possibilities of pluripotency and early development studies. Generation of order Carnivora iPS cells from dog (Canis lupus familiaris), snow leopard (Panthera uncia), and American mink (Neovison vison) was previously reported. The aim of the current study was to examine conditions of pinniped fbroblast reprogramming. Pinnipeds are representatives of the suborder Caniformia sharing conservative genomes. There are several ways to deliver reprogramming transcription factors: RNA, proteins, plasmids, viral vectors etc. The most effective delivery systems for mouse and human cells are based on viral vectors. We compared a lentiviral vector which integrates into the genome and a Sendai virus­based vector, CytoTune EmGFP Sendai Fluorescence Reporter. The main advantage of Sendai virus­based vectors is that they do not integrate into the genome. We performed delivery of genetic constructions carrying fluorescent proteins to fbroblasts of seven Pinnipeds: northern fur seal (Callorhinus ursinus), Steller sea lion (Eumetopias jubatus), walrus (Odobenus rosmarus), bearded seal (Erignathus barbatus), Baikal seal (Pusa sibirica), ringed seal (Phoca hispida), and spotted seal (Phoca largha). We also transduced American mink (N. vison), human (Homo sapiens), and mouse (Mus musculus) fbroblasts as a control. We showed that the Sendai virus­based transduction system provides transgene expression one­two orders of magnitude higher than the lentiviral system at a comparable multiplicity of infection. Also, transgene expression after Sendai virus­based transduction is quite stable and changes only slightly at day four compared to day two. These data allow us to suggest that Sendai virus­based vectors are preferable for generation of Pinniped iPS cells.

Stranding trends of Steller sea lions Eumetopias jubatus 1990-2015

Distinct population segments of Steller sea lion (SSL)Eumetopias jubatushave experienced different population trends over the last 5 decades, rendering the need for retrospective study. By identifying long-term stranding trends of SSLs we can develop a better understanding of factors contributing to mortality that may affect SSL population dynamics. We characterized spatial and temporal trends of SSL strandings (n = 1507) in Alaska, Oregon, and Washington, USA, over a 25 yr period. Stranding reports were obtained from the Alaska and Northwest Region’s Marine Mammal Stranding Networks. Temporal trends were assessed by identifying seasonal patterns across all years (1990-2015), analyzing sex, age class, body length, and characterizing signs of human interaction including factors contributing to mortality. An apparent increase in strandings occurred after 2000, likely due to increased stranding response effort resulting from increased federal grant awards. Adult males were the most frequently stranded sex and age class in the Alaska (AK) and Northwest (NW) Regions. Clear seasonality trends were evident, with the greatest reported stranding occurrences during the spring and summer. Gunshot wounds and fishery interactions accounted for a large proportion (90%) of human interaction cases. In Alaska, the southeast region had the highest number of strandings. In the NW Region, Oregon had the highest documented strandings. Despite caveats associated with stranding data, our findings suggest rapid timing of continued stranding response is imperative for a better understanding of cause-specific mortality trends and other factors contributing to stranding events.

Changes in adult Chinook salmon (Oncorhynchus tshawytscha) survival within the lower Columbia River amid increasing pinniped abundance

Considerable effort towards conservation has contributed to the recovery of historically depleted pinniped populations worldwide. However, in several locations where pinnipeds have increased, they have been blamed for preventing the recovery of commercially valuable fish species through predation. Prompted by increasing pinniped abundance within the Columbia River (CR), USA, over a 6-year period, we used passive integrated transponder tags to measure the survival of adult spring-run Chinook salmon (Oncorhynchus tshawytscha) through the estuary and lower CR to Bonneville Dam (river kilometre 234). We estimated 51 751 – 224 705 salmon died annually within this reach from sources other than harvest. Mixed-effects logistic regression modelling identified pinniped predation as the most likely source of this mortality. The odds of survival was estimated to decrease by 32% (95% CI: 6%–51%) for every additional 467 sea lions (Zalophus californianus and Eumetopias jubatus) present within the CR and to increase by 32% (95% CI: 8%–61%) for every increase of 1.5 in the log of American shad (Alosa sapidissima), a potential prey item for sea lions.

Spatial distribution, movements, and geographic range of Steller sea lions (Eumetopias jubatus) in Alaska.

The two stocks of Steller sea lions (Eumetopias jubatus) in Alaska include an endangered western stock, recently recovering in parts of its range following decades of decline, and an eastern stock which was removed from the U.S. Endangered Species List in 2013 following increasing numbers since the 1970s. Information on overlapping distributions of eastern and western sea lions is needed for management considerations. We analyzed >30,000 sightings collected from 2000–2014 of 2,385 sea lions that were branded as pups at 10 Alaskan rookeries to examine mesoscale (mostly <500km) spatial distribution, geographic range, and geographic population structure based on natal rookery, sex, and age during breeding and non-breeding seasons. Analyses of summary movement measures (e.g., natal rookery, sex, and age-class differences in spatial distribution and geographic range) indicate wide variation in rookery-specific movement patterns. Correlations between movement measures and population dynamics suggested movement patterns could be a function of density dependence. Animals from larger rookeries, and rookeries with slower population growth and lower survival, had wider dispersion than animals from smaller rookeries, or rookeries with high growth and survival. Sea lions from the largest rookery, Forrester Island, where survival and population trends are lowest, were the most widely distributed. Analysis of geographic population structure indicated that animals born in the eastern Aleutian Islands had the most distinct movements and had little overlap with other western sea lions. Northern Southeast Alaska, within the eastern stock, is the area of greatest overlap between stocks, and is important to western animals, especially those born in Prince William Sound. Detailed knowledge of distribution and movements of western sea lions is useful for defining recovery and population trend analysis regions that better reflect dispersion and population structure and provides valuable information to managers as critical habitat is re-evaluated and the location of the stock boundary reconsidered.

Variation in milk, serum, and blubber fatty acids in young, free‐ranging Steller sea lions

AbstractWe determined the fatty acid signatures in milk, serum, and blubber samples collected from young free‐ranging Steller sea lions (Eumetopias jubatus) and investigated the partitioning of fatty acids among these matrices. We assessed the relationship of fatty acids in each matrix with region, age, season, sex, and body condition to gain information needed to determine the most appropriate type of samples to collect and analyze to address future research questions. The variability of fatty acid composition was almost entirely explained by sample type, highlighting the importance of selecting a matrix consistent with the study objectives. Regional differences in fatty acid composition were found in all sample types and these differences varied among matrices. The proportion of fatty acids in milk and serum were influenced by season of capture whereas blubber samples were more affected by age of the pup. The influence of season on the fatty acid signatures in milk and serum highlights the use of these samples over blubber in studies investigating seasonal changes in diet. Further, our findings suggest that the use of milk samples collected from the stomachs of pups may be a viable alternative to directly collecting milk from adult females.

Coxiella burnetii in wild mammals: A systematic review.

Coxiella burnetii is a multi-host bacterium that causes Q fever in humans, a zoonosis that is emerging worldwide. The ecology of C.burnetii in wildlife is still poorly understood and the influence of host, environmental and pathogen factors is almost unknown. This study gathers current published information on different aspects of C.burnetii infection in wildlife, even in species with high reservoir potential and a high rate of interaction with livestock and humans, in order to partially fill the existing gap and highlight future needs. Exposure and/or infection by C.burnetii has, to date, been reported in 109 wild mammal species. The limited sample size of most of the existing studies could suggest an undervalued prevalence of C.burnetii infection. Knowledge on the clinical outcome of C.burnetii infection in wildlife is also very limited, but currently includes reproductive failure in waterbuck (Kobus ellipsiprymnus), roan antelope (Hippotragus niger), dama gazelle (Nanger dama) and water buffalo (Bubalus bubalis) and placentitis in the Pacific harbor seal (Phoca vitulina richardsi), Steller sea lion (Eumetopias jubatus) and red deer (Cervus elaphus). The currently available serological tests need to be optimised and validated for each wildlife species. Finally, there is a huge gap in the research on C.burnetii control in wildlife, despite of the increasing evidence that wildlife is a source of C.burnetii for both livestock and humans.

Deciphering the evolutionary signatures of pinnipeds using novel genome sequences: The first genomes of Phoca largha, Callorhinus ursinus, and Eumetopias jubatus

The pinnipeds, which comprise seals, sea lions, and walruses, are a remarkable group of marine animals with unique adaptations to semi-aquatic life. However, their genomes are poorly characterized. In this study, we sequenced and characterized the genomes of three pinnipeds (Phoca largha, Callorhinus ursinus, and Eumetopias jubatus), focusing on site-wise sequence changes. We detected rapidly evolving genes in pinniped lineages and substitutions unique to pinnipeds associated with amphibious sound perception. Phenotypic convergence-related sequence convergences are not common in marine mammals. For example, FASN, KCNA5, and IL17RA contain substitutions specific to pinnipeds, yet are potential candidates of phenotypic convergence (blubber, response to hypoxia, and immunity to pathogens) in all marine mammals. The outcomes of this study will provide insight into targets for future studies of convergent evolution or gene function.