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Donald G Calkins - One of the best experts on this subject based on the ideXlab platform.
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anthropogenic causes of the western steller Sea Lion eumetopias jubatus population decline and their threat to recovery
Mammal Review, 2008Co-Authors: Shannon Atkinson, Douglas P Demaster, Donald G CalkinsAbstract:1 The western Steller Sea Lion Eumetopias jubatus population has experienced a chronic decline since the 1960s. The causes are likely multifactorial and a combination of anthropogenic and natural factors. A draft revised recovery plan for the Steller Sea Lion has been published by the US National Marine Fisheries Service, listing both anthropogenic and natural factors that may have contributed to the observed decline or which may be a threat to the recovery of the western Steller Sea Lion population. The purpose of this review is to consider the anthropogenic threats to this stock. 2 Anthropogenic sources of mortality include fisheries competition resulting in nutritional stress, mortality incidental to commercial fisheries (i.e. fisheries by-catch), subsistence hunts, legal and illegal shooting, commercial hunts, anthropogenic-related contamination, and reSearch-induced mortalities. 3 We present evidence that the following anthropogenic factors likely contributed to the decline of the western Steller Sea Lion population over the last 40 years: (i) mortality incidental to commercial fisheries (i.e. by-catch); (ii) commercial hunting of western Steller Sea Lions; and (iii) legal and illegal shooting; whereas the subsistence hunts for western Steller Sea Lions and mortality incidental to reSearch were not likely to be contributors to the observed decline. 4 Further, we present evidence that the following can be excluded as significant anthropogenic threats to the recovery of the western Steller Sea Lion population: (i) mortality incidental to commercial fishing; (ii) legal and illegal shooting; (iii) commercial hunts of Steller Sea Lions; (iv) subsistence hunting; and (v) mortality incidental to reSearch. 5 Competition with fisheries resulting in nutritional stress, and the potential impacts of contaminants, are two anthropogenic factors that should continue to be a priority for the various organizations currently doing reSearch on this population.
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steller Sea Lion status and trend in southeast alaska 1979 1997
Marine Mammal Science, 1999Co-Authors: Donald G Calkins, D C Mallister, Kenneth W Pitcher, Grey W PendletonAbstract:Steller Sea Lion (Eumetopias jubatus) numbers in the United States declined by about 75% over the past 20+ yr. They are classified, under the U. S. Endangered Species Act, as “threatened” in the eastern portion of their range and as “endangered” in the western portion. We analyzed trends in numbers of pup and non-pup Steller Sea Lions counted in Southeast Alaska between 1979 and 1997. Sea Lion numbers, based on counts of pups on rookeries, increased by an average of 5.9% per year between 1979 and 1997. However, numbers of pups increased at a much slower rate (+ 1.7% per year) between 1989 and 1997. For counts of non-pup Steller Sea Lions we used models that controlled for the effects of date, time, and tide at the time of the survey to analyze trends. This technique reduced bias and increased precision of the resulting trend estimates. Numbers of Sea Lions were stable (+0.5%) between 1989 and 1996, based on counts of non-pups. We estimated the Southeast Alaska breeding population of Steller Sea Lions at about 19,000 animals of all ages in 1997, a level that is probably near the highest in recorded history.
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STELLER Sea Lion STATUS AND TREND IN SOUTHEAST ALASKA: 1979–1997
Marine Mammal Science, 1999Co-Authors: Donald G Calkins, D C Mallister, Kenneth W Pitcher, Grey W PendletonAbstract:Steller Sea Lion (Eumetopias jubatus) numbers in the United States declined by about 75% over the past 20+ yr. They are classified, under the U. S. Endangered Species Act, as “threatened” in the eastern portion of their range and as “endangered” in the western portion. We analyzed trends in numbers of pup and non-pup Steller Sea Lions counted in Southeast Alaska between 1979 and 1997. Sea Lion numbers, based on counts of pups on rookeries, increased by an average of 5.9% per year between 1979 and 1997. However, numbers of pups increased at a much slower rate (+ 1.7% per year) between 1989 and 1997. For counts of non-pup Steller Sea Lions we used models that controlled for the effects of date, time, and tide at the time of the survey to analyze trends. This technique reduced bias and increased precision of the resulting trend estimates. Numbers of Sea Lions were stable (+0.5%) between 1989 and 1996, based on counts of non-pups. We estimated the Southeast Alaska breeding population of Steller Sea Lions at about 19,000 animals of all ages in 1997, a level that is probably near the highest in recorded history.
Isabelle Charrier - One of the best experts on this subject based on the ideXlab platform.
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adult male australian Sea Lion barking calls reveal clear geographical variations
Animal Behaviour, 2014Co-Authors: Isabelle Charrier, Robert G Harcourt, Heidi Ahonen, Adam J StowAbstract:Vocalizing by males plays an important role in the reproductive activities of many species. Geographical variation in the characteristics of male vocalization is well studied in birds, but largely unexplored in mammals. This study quantified the extent of geographical variation in male Australian Sea Lion, Neophoca cinerea, barking calls and examined what drives vocal differences in this species. We recorded male barking calls from seven breeding colonies separated by ca. 5–2700 km enabling us to investigate acoustic differences on both micro- and macrogeographical scales. Our results revealed significant nonuniform geographical variation across colonies. Neither genetic nor geographical distances between colonies fully explained the observed acoustic variation. We suggest that environmental or morphological factors are likely to further contribute to differences in vocal characteristics.
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individual identity encoding and environmental constraints in vocal recognition of pups by australian Sea Lion mothers
Animal Behaviour, 2012Co-Authors: Isabelle Charrier, Benjamin J Pitcher, Robert G HarcourtAbstract:Colonial living imposes strong selection pressures on the communication systems of species with many animals communicating on the same sensory channels simultaneously. Colonial species often exhibit complex individual vocal signatures that encode a caller’s identity in their vocalizations. During lactation, Australian Sea Lion, Neophoca cinerea, mothers and pups are repeatedly separated when mothers leave the colony to forage. After maternal foraging trips, mothers and pups must reunite in the colony. Both mothers and pups produce individually distinctive vocalizations during reunions and can recognize their counterpart’s calls. Using playback experiments with modified calls, we investigated the acoustic parameters involved in the recognition of pup vocalizations by mothers. We also examined the efficiency of the vocal signature in three habitat types within the colony using propagation tests. We found that Australian Sea Lion females used a combination of temporal, amplitude and frequency parameters to recognize their pup’s vocalizations. Pup vocalizations were severely degraded in the herbaceous dune habitat type with no vocal signature components reliably propagating to any measured distance. By contrast, calls propagated comparatively well in the shrubby dune habitat of the colony, as the vegetation appeared to act as a windshield. This study shows that the vocal signatures of Australian Sea Lion pups are both shaped and constrained by their environment and ecology, and that these signatures are of a moderate level of complexity when compared to those of other colonial vertebrates.
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Individual identity encoding and environmental constraints in vocal recognition of pups by Australian Sea Lion mothers
Animal Behaviour, 2012Co-Authors: Benjamin J Pitcher, Robert G Harcourt, Isabelle CharrierAbstract:Colonial living imposes strong selection pressures on the communication systems of species with many animals communicating on the same sensory channels simultaneously. Colonial species often exhibit complex individual vocal signatures that encode a caller's identity in their vocalizations. During lactation, Australian Sea Lion, Neophoca cinerea, mothers and pups are repeatedly separated when mothers leave the colony to forage. After maternal foraging trips, mothers and pups must reunite in the colony. Both mothers and pups produce individually distinctive vocalizations during reunions and can recognize their counterpart's calls. Using playback experiments with modified calls, we investigated the acoustic parameters involved in the recognition of pup vocalizations by mothers. We also examined the efficiency of the vocal signature in three habitat types within the colony using propagation tests. We found that Australian Sea Lion females used a combination of temporal, amplitude and frequency parameters to recognize their pup's vocalizations. Pup vocalizations were severely degraded in the herbaceous dune habitat type with no vocal signature components reliably propagating to any measured distance. By contrast, calls propagated comparatively well in the shrubby dune habitat of the colony, as the vegetation appeared to act as a windshield. This study shows that the vocal signatures of Australian Sea Lion pups are both shaped and constrained by their environment and ecology, and that these signatures are of a moderate level of complexity when compared to those of other colonial vertebrates. © 2011 The Association for the Study of Animal Behaviour.
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Rapid onset of maternal vocal recognition in a colonially breeding mammal, the australian Sea Lion
PLoS ONE, 2010Co-Authors: Benjamin J Pitcher, Robert G Harcourt, Isabelle CharrierAbstract:BACKGROUND: In many gregarious mammals, mothers and offspring have developed the abilities to recognise each other using acoustic signals. Such capacity may develop at different rates after birth/parturition, varying between species and between the participants, i.e., mothers and young. Differences in selective pressures between species, and between mothers and offspring, are likely to drive the timing of the onset of mother-young recognition. We tested the ability of Australian Sea Lion mothers to identify their offspring by vocalisation, and examined the onset of this behaviour in these females. We hypothesise that a rapid onset of recognition may reflect an adaptation to a colonial lifestyle.\n\nPRINCIPAL FINDINGS: In a playback study maternal responses to own pup and non-filial vocalisations were compared at 12, 24 and every subsequent 24 hours until the females' first departure post-partum. Mothers showed a clear ability to recognise their pup's voice by 48 hours of age. At 24 hours mothers called more, at 48 hours they called sooner and at 72 hours they looked sooner in response to their own pup's vocalisations compared to those of non-filial pups.\n\nCONCLUSIONS: We demonstrate that Australian Sea Lion females can vocally identify offspring within two days of birth and before mothers leave to forage post-partum. We suggest that this rapid onset is a result of selection pressures imposed by a colonial lifestyle and may be seen in other colonial vertebrates. This is the first demonstration of the timing of the onset of maternal vocal recognition in a pinniped species.
Grey W Pendleton - One of the best experts on this subject based on the ideXlab platform.
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steller Sea Lion status and trend in southeast alaska 1979 1997
Marine Mammal Science, 1999Co-Authors: Donald G Calkins, D C Mallister, Kenneth W Pitcher, Grey W PendletonAbstract:Steller Sea Lion (Eumetopias jubatus) numbers in the United States declined by about 75% over the past 20+ yr. They are classified, under the U. S. Endangered Species Act, as “threatened” in the eastern portion of their range and as “endangered” in the western portion. We analyzed trends in numbers of pup and non-pup Steller Sea Lions counted in Southeast Alaska between 1979 and 1997. Sea Lion numbers, based on counts of pups on rookeries, increased by an average of 5.9% per year between 1979 and 1997. However, numbers of pups increased at a much slower rate (+ 1.7% per year) between 1989 and 1997. For counts of non-pup Steller Sea Lions we used models that controlled for the effects of date, time, and tide at the time of the survey to analyze trends. This technique reduced bias and increased precision of the resulting trend estimates. Numbers of Sea Lions were stable (+0.5%) between 1989 and 1996, based on counts of non-pups. We estimated the Southeast Alaska breeding population of Steller Sea Lions at about 19,000 animals of all ages in 1997, a level that is probably near the highest in recorded history.
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STELLER Sea Lion STATUS AND TREND IN SOUTHEAST ALASKA: 1979–1997
Marine Mammal Science, 1999Co-Authors: Donald G Calkins, D C Mallister, Kenneth W Pitcher, Grey W PendletonAbstract:Steller Sea Lion (Eumetopias jubatus) numbers in the United States declined by about 75% over the past 20+ yr. They are classified, under the U. S. Endangered Species Act, as “threatened” in the eastern portion of their range and as “endangered” in the western portion. We analyzed trends in numbers of pup and non-pup Steller Sea Lions counted in Southeast Alaska between 1979 and 1997. Sea Lion numbers, based on counts of pups on rookeries, increased by an average of 5.9% per year between 1979 and 1997. However, numbers of pups increased at a much slower rate (+ 1.7% per year) between 1989 and 1997. For counts of non-pup Steller Sea Lions we used models that controlled for the effects of date, time, and tide at the time of the survey to analyze trends. This technique reduced bias and increased precision of the resulting trend estimates. Numbers of Sea Lions were stable (+0.5%) between 1989 and 1996, based on counts of non-pups. We estimated the Southeast Alaska breeding population of Steller Sea Lions at about 19,000 animals of all ages in 1997, a level that is probably near the highest in recorded history.
Jamie N Womble - One of the best experts on this subject based on the ideXlab platform.
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steller Sea Lion foraging response to Seasonal changes in prey availability
Marine Ecology Progress Series, 2009Co-Authors: Michael F. Sigler, Johanna J Vollenweider, John F Thedinga, David J Csepp, Jamie N Womble, Mandy Wong, Michael J Rehberg, Dominic J Tollit, Andrew W. TritesAbstract:We hypothesized that: (1) Steller Sea Lion Eumetopias jubatus diet choice is a function of prey availability, (2) Sea Lions move to take advantage of times and locations of Seasonal prey concentrations and (3) the number present depends on the amount of prey available (numerical response). Over 3 yr, typically on a quarterly basis, in Frederick Sound, SE Alaska, multiple measurements were taken of Steller Sea Lion abundance (aerial surveys), diet (scats), dive behavior (satellite telemetry) and prey availability and caloric density (nearshore, pelagic and demersal fish surveys). We found that Steller Sea Lions shifted diet composition in response to changes in prey availability of pollock Theragra chalcogramma, hake Merluccius productus, herring Clupea pallasi and salmon Oncorhynchus spp. They selected intermediate-sized fish and avoided small ( 60 cm) fish, and moved between areas as prey became available Seasonally. The number of Sea Lions present depended on the amount of prey available; a standing biomass of 500 to 1700 t of prey in a nonbreeding area such as Frederick Sound, depending on species composition, can attract and sustain about 500 Sea Lions. Pollock was more frequent in Sea Lion diet in inside waters of SE Alaska — including Frederick Sound, Stephens Passage and Lynn Canal — than anywhere else in Alaska and contributed ~⁄3 of the dietary energy in Frederick Sound. This finding implies that a diet with substantial year-round contributions from less nutritious, but abundant prey such as pollock can form part of a healthy diet as long as more nutritious prey such as herring, salmon or eulachon Thaleichthys pacificus also are consumed. Our study supports the conclusion that the Steller Sea Lion is an opportunistic marine predator with a flexible foraging strategy that selects abundant, accessible prey and shifts among Seasonally available species.
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linking Seasonal distribution patterns with prey availability in a central place forager the steller Sea Lion
Journal of Biogeography, 2009Co-Authors: Jamie N Womble, Michael F. Sigler, Mary F WillsonAbstract:Aim We used a novel approach to infer foraging areas of a central-place forager, the Steller Sea Lion (Eumetopias jubatus), by assessing changes in the temporal and spatial distribution patterns of Sea Lions at terrestrial sites. Specifically, our objectives were (1) to classify Seasonal distribution patterns of Steller Sea Lions and (2) to determine to what extent the Seasonal distribution of Steller Sea Lions is explained by Seasonal concentrations of prey. Location Southeast Alaska, USA.
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Seasonal availability of abundant energy rich prey influences the abundance and diet of a marine predator the steller Sea Lion eumetopias jubatus
Marine Ecology Progress Series, 2006Co-Authors: Jamie N Womble, Michael F. SiglerAbstract:Steller Sea Lions Eumetopias jubatus are central-place foragers that forage in the marine environment while using terrestrial sites to rest and care for young. Some terrestrial sites are used Seasonally; however, the reasons for doing so are not fully understood. We addressed the hypothesis that Seasonal availability of prey influences Seasonal abundance and diet of Sea Lions. We quantified monthly prey availability and Sea Lion abundance and quarterly diet composition at Benjamin Island in SE Alaska (2001-2004). Large numbers of Sea Lions occupied Benjamin Island during the non- breeding Season from October to April when Pacific herring Clupea pallasii biomass was highest. Herring was the most common species in Sea Lion diet (frequency of occurrence (FO) = 90%) and comprised over 81% of the available pelagic prey biomass and 96% of the energy encountered dur- ing pelagic surveys. Walleye pollock Theragra chalcogramma accounted for 19% of the available prey biomass but was only slightly less common in Sea Lion diet (FO = 88%) than herring. Herring bio- mass was correlated with the number of Sea Lions; in contrast, there was no relationship between pol- lock biomass and number of Sea Lions. Several fish species were found in nearshore areas, but were uncommon in Sea Lion diet. Sea Lions consumed the available pelagic prey but little of the available nearshore prey. The FO of herring and pollock in Sea Lion diet did not differ significantly between Seasons; however, the FO of other Seasonal prey species differed between Seasons. Seasonal occupa- tion of Benjamin Island by Sea Lions is influenced by Seasonally available, densely aggregated, energy-rich prey.
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Temporal Variation in Steller Sea Lion Diet at a Seasonal Haul-Out in Southeast Alaska
Sea Lions of the World, 2006Co-Authors: Jamie N Womble, Michael F. SiglerAbstract:Pinniped diet may vary spatially and temporally and can be influenced by prey availability. Several prey species of Steller Sea Lions are densely aggregated during the nonbreeding Season of Sea Lions and may be Seasonally important because Sea Lion energetic requirements increase during winter and spring. To assess temporal variation in Steller Sea Lion diet at Benjamin Island in Lynn Canal, Southeast Alaska, we collected scat samples (n = 787) each February, April, October, and December from 2001 to 2004. Scat samples were not collected during summer because few Sea Lions were present at Benjamin Island during that Season. Pacific herring (frequency of occurrence [FO] = 90.0%) and walleye pollock (FO = 87.5%) were the two most common prey species in Sea Lion scat samples, followed by skate, Pacific salmon, Pacific cod, capelin, cephalopods, north ern lampfish, sculpins, arrowtooth flounder, eulachon, and Pacific hake. The FO of herring, pollock, skates, Pacific cod, and cephalopods did not differ significantly between Seasons; however, the FO of capelin, Pacific salmon, northern lampfish, sculpins, arrowtooth flounder, eulachon, and Pacific hake differed between Seasons. Sea Lion diet diversity increased in spring and corresponded to the spawning Season of several forage fish species. Exploiting salmon in fall, herring during winter, and eulachon, capelin, and northern lampfish in spring likely helps Sea Lions meet the increased energetic demands that occur during winter and spring.
Frances M D Gulland - One of the best experts on this subject based on the ideXlab platform.
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complex virome in a mesenteric lymph node from a californian Sea Lion zalophus californianus with polyserositis and steatitis
Viruses, 2020Co-Authors: Eda Altan, Kathleen M Colegrove, Frances M D Gulland, Terry R Spraker, Martha A Delaney, Elizabeth A Wheeler, Xutao Deng, Yanpeng Li, Eric DelwartAbstract:An emaciated subadult free-ranging California Sea Lion (Csl or Zalophus californianus) died following stranding with lesions similar to 11 other stranded animals characterized by chronic disseminated granulomatous inflammation with necrotizing steatitis and vasculitis, involving visceral adipose tissues in the thoracic and peritoneal cavities. Histologically, affected tissues had extensive accumulations of macrophages with perivascular lymphocytes, plasma cells, and fewer neutrophils. Using viral metagenomics on a mesenteric lymph node six mammalian viruses were identified consisting of novel parvovirus, polyomavirus, rotavirus, anellovirus, and previously described Csl adenovirus 1 and Csl bocavirus 4. The causal or contributory role of these viruses to the gross and histologic lesions of this Sea Lion remains to be determined.
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common cancer in a wild animal the california Sea Lion zalophus californianus as an emerging model for carcinogenesis
Philosophical Transactions of the Royal Society B, 2015Co-Authors: Helen M Browning, Kathleen M Colegrove, Frances M D Gulland, John A Hammond, Ailsa J HallAbstract:Naturally occurring cancers in non-laboratory species have great potential in helping to decipher the often complex causes of neoplasia. Wild animal models could add substantially to our understanding of carcinogenesis, particularly of genetic and environmental interactions, but they are currently underutilized. Studying neoplasia in wild animals is difficult and especially challenging in marine mammals owing to their inaccessibility, lack of exposure history, and ethical, logistical and legal limits on experimentation. Despite this, California Sea Lions ( Zalophus californianus ) offer an opportunity to investigate risk factors for neoplasia development that have implications for terrestrial mammals and humans who share much of their environment and diet. A relatively accessible California Sea Lion population on the west coast of the USA has a high prevalence of urogenital carcinoma and is regularly sampled during veterinary care in wildlife rehabilitation centres. Collaborative studies have revealed that genotype, persistent organic pollutants and a herpesvirus are all associated with this cancer. This paper reviews reSearch to date on the epidemiology and pathogenesis of urogenital carcinoma in this species, and presents the California Sea Lion as an important and currently underexploited wild animal model of carcinogenesis.
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Development of a Serological Assay for the Sea Lion (Zalophus californianus) Anellovirus, ZcAV.
Scientific Reports, 2015Co-Authors: Elizabeth Fahsbender, Frances M D Gulland, Karyna Rosario, John P. Cannon, Larry J. Dishaw, Mya BreitbartAbstract:New diSeases in marine animals are emerging at an increasing rate, yet methodological limitations hinder characterization of viral infections. Viral metagenomics is an effective method for identifying novel viruses in diSeased animals; however, determining virus pathogenesis remains a challenge. A novel anellovirus (Zalophus californianus anellovirus, ZcAV) was recently reported in the lungs of captive California Sea Lions involved in a mortality event. ZcAV was not detected by PCR in the blood of these animals, creating the inability to assess the prevalence of ZcAV in live Sea Lions. This study developed an enzyme-linked immunosorbent assay (ELISA) to detect antibodies to ZcAV in Sea Lion serum. To assess ZcAV prevalence, paired serum and lung samples (n = 96) from wild Sea Lions that stranded along the California coast were tested through ELISA and PCR, respectively. Over 50% of the samples tested positive for ZcAV by ELISA (34%), PCR (29%), or both (11%) assays. ZcAV is prevalent in stranded wild Sea Lion populations and results suggest that PCR assays alone may grossly underestimate ZcAV exposure. This ELISA provides a tool for testing live Sea Lions for ZcAV exposure and is valuable for subsequent studies evaluating the potential pathogenicity of this anellovirus.
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phylogenomic characterization of california Sea Lion adenovirus 1
Infection Genetics and Evolution, 2015Co-Authors: Galaxia Corteshinojosa, Frances M D Gulland, Rebecca Rivera, Stephanie Vennwatson, Tracey Goldstein, Thomas B Waltzek, Marco Salemi, James F X WellehanAbstract:Abstract Significant adenoviral diversity has been found in humans, but in domestic and wild animals the number of identified viruses is lower. Here we present the complete genome of a recently discovered mastadenovirus, California Sea Lion adenovirus 1 (CSLAdV-1) isolated from California Sea Lions ( Zalophus californianus ), an important pathogen associated with hepatitis in pinnipeds. The genome of this virus has the typical mastadenoviral structure with some notable differences at the carboxy-terminal end, including a dUTPase that does not cluster with other mastadenoviral dUTPases, and a fiber that shows similarity to a trans-sialidase of Trypanosoma cruzi and choline-binding protein A (CbpA) of Streptococcus pneumoniae . The GC content is low (36%), and phylogenetic analyses placed the virus near the root of the clade infecting laurasiatherian hosts in the genus Mastadenovirus . These findings support the hypothesis that CSLAdV-1 in California Sea Lions represents a host jump from an unknown mammalian host in which it is endemic.
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sesavirus prototype of a new parvovirus genus in feces of a Sea Lion
Virus Genes, 2015Co-Authors: Frances M D Gulland, Claire Simeone, Xutao Deng, Eric Delwart, Tung Gia PhanAbstract:We describe the nearly complete genome of a highly divergent parvovirus, we tentatively name Sesavirus, from the feces of a California Sea Lion pup (Zalophus californianus) suffering from malnutrition and pneumonia. The 5,049-base-long genome contained two major ORFs encoding a 553-aa nonstructural protein and a 965-aa structural protein which shared closest amino acid identities of 25 and 28 %, respectively, with members of the copiparvovirus genus known to infect pigs and cows. Given the low degree of similarity, Sesavirus might be considered as prototype for a new genus with a proposed name of Marinoparvovirus in the subfamily Parvovirinae.