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C Caudillchristopher - One of the best experts on this subject based on the ideXlab platform.

  • influence of Pinniped caused injuries on the survival of adult chinook salmon oncorhynchus tshawytscha and steelhead trout oncorhynchus mykiss in the columbia river basin
    Canadian Journal of Fisheries and Aquatic Sciences, 2011
    Co-Authors: P Naughtongeorge, L Keefermatthew, S Claboughtami, A Jepsonmichael, R Leesteven, A Peerychristopher, C Caudillchristopher
    Abstract:

    Increasing Pinniped abundance in the Pacific Northwest has coincided with population declines of Pacific salmon (Oncorhynchus spp.) and steelhead trout (Oncorhynchus mykiss), and concentrated predation may affect the recovery of some threatened and endangered salmonid stocks. We used radiotelemetry to evaluate Pinniped-caused injury effects on migration survival of 17 007 adult Columbia River Chinook salmon (Oncorhynchus tshawytscha) and steelhead trout. Injuries from Pinnipeds were common (mean injury rate across 29 run-years = 36.5%) and were most common for spring Chinook salmon and steelhead trout. Injury was not consistently associated with adult survival to spawning tributaries, but some negative survival effects were detected. Pinniped-caused injury rates decreased as annual run sizes increased, indicating density-dependent or saturation effects. Within a run, large fish generally had a higher injury incidence than small fish, suggesting Pinnipeds targeted large fish or more efficiently captured sm...

P Naughtongeorge - One of the best experts on this subject based on the ideXlab platform.

  • influence of Pinniped caused injuries on the survival of adult chinook salmon oncorhynchus tshawytscha and steelhead trout oncorhynchus mykiss in the columbia river basin
    Canadian Journal of Fisheries and Aquatic Sciences, 2011
    Co-Authors: P Naughtongeorge, L Keefermatthew, S Claboughtami, A Jepsonmichael, R Leesteven, A Peerychristopher, C Caudillchristopher
    Abstract:

    Increasing Pinniped abundance in the Pacific Northwest has coincided with population declines of Pacific salmon (Oncorhynchus spp.) and steelhead trout (Oncorhynchus mykiss), and concentrated predation may affect the recovery of some threatened and endangered salmonid stocks. We used radiotelemetry to evaluate Pinniped-caused injury effects on migration survival of 17 007 adult Columbia River Chinook salmon (Oncorhynchus tshawytscha) and steelhead trout. Injuries from Pinnipeds were common (mean injury rate across 29 run-years = 36.5%) and were most common for spring Chinook salmon and steelhead trout. Injury was not consistently associated with adult survival to spawning tributaries, but some negative survival effects were detected. Pinniped-caused injury rates decreased as annual run sizes increased, indicating density-dependent or saturation effects. Within a run, large fish generally had a higher injury incidence than small fish, suggesting Pinnipeds targeted large fish or more efficiently captured sm...

Ronald J Schusterman - One of the best experts on this subject based on the ideXlab platform.

  • Acoustic production mechanisms in Pinnipeds
    The Journal of the Acoustical Society of America, 2008
    Co-Authors: Marija Spasikova, Colleen Reichmuth, W. T. Fitch, Ronald J Schusterman
    Abstract:

    The ability to develop articulate speech relies on capabilities that became available to our ancestors through changes in both peripheral mechanisms (vocal acoustics and anatomy) and neural mechanisms (vocal control and imitation). Few distantly related species (cetaceans, birds and Pinnipeds) have shown the ability of vocal imitation, but of the three, only the Pinnipeds use the same vocal tract as us humans. For this reason we choose to study two closely related Pinniped species: the harbour seal (Phoca Vitulina), a good vocal imitator (capable of complex vocal learning), and the Californian sea lion (Zalophus californicus), a close relative with very limited vocal imitation capabilities (no evidence of complex vocal learning) to look at the acoustical production mechanisms of the species as well as the neural mechanisms underlying the same. Using previously acquired data gathered in California at the Long Marine Lab, we performed video and acoustic analysis to show correlation between jaw opening and formants frequencies in the harbour seal (Phoca Vitulina), in speech like vocalisations. We are examining the involvement of tongue movement during these vocalisations, hypothesising that it will account for the remaining residuals in the correlation between the formants excursions and the jaw movements.

  • minimum audible angles for aerial pure tones in a northern elephant seal mirounga angustirostris
    Journal of the Acoustical Society of America, 2005
    Co-Authors: Marla M Holt, Ronald J Schusterman, Brandon L Southall, David Kastak
    Abstract:

    Recent work has shown that several Pinniped species localize aerial broadband signals as accurately as some terrestrial carnivores. Additionally, both harbor seals and California sea lions can better localize both the lower and higher frequencies of their hearing range compared to performance at intermediate frequencies. These results are congruent with the duplex theory of sound localization which states that low frequencies are localized by interaural time differences while high frequencies are localized by interaural intensity differences. Northern elephant seals are land breeding Pinnipeds whose range of best hearing sensitivity is shifted toward lower frequencies compared to other Pinnipeds tested thus far. In this study, we tested a female northern elephant seal in a hemi‐anechoic chamber at six frequencies ranging between 0.8 and 16 kHz that were presented at levels approximately 25 dB above threshold. A left/right behavioral procedure was used to measure minimum audible angles (MAAs) at 75 percent...

  • Reliability of underwater hearing thresholds in Pinnipeds
    Acoustics Research Letters Online, 2005
    Co-Authors: Brandon L Southall, Ronald J Schusterman, David Kastak, Colleen Reichmuth Kastak
    Abstract:

    Repeated measures of low-frequency underwater hearing sensi- tivity in individuals of three Pinniped species tested over 4-7 years are pre- sented. Despite changes in the experience of the subjects and certain testing parameters (e.g., equipment and research personnel), measured underwater hearing thresholds within subjects over relatively long periods of time were quite similar at the frequencies tested (0.2-6.4 kHz). These data address the reliability of acoustic signal detection measurements over time in Pinnipeds using psychophysical techniques. They are also relevant in considering the cumulative effects of aging, experience, and noise exposure on Pinniped hear- ing in certain frequency bands.

  • Localization of aerial broadband noise by Pinnipeds.
    The Journal of the Acoustical Society of America, 2004
    Co-Authors: Marla M Holt, Ronald J Schusterman, Brandon L Southall, David Kastak
    Abstract:

    Although many Pinnipeds (seals, sea lions, and walruses) emit broadband calls on land as part of their communication system, few studies have addressed these animals’ ability to localize aerial broadband sounds. In this study, the aerial sound localization acuities of a female northern elephant seal (Mirounga angustirostris), a male harbor seal (Phoca vitulina), and a female California sea lion (Zalophus californianus) were measured in the horizontal plane. The stimulus was broadband white noise that was band pass filtered between 1.2 and 15 kHz. Testing was conducted in a hemi-anechoic chamber using a left/right forced choice procedure to measure the minimum audible angle (MAA) for each subject. MAAs were defined as half the angular separation of two sound sources bisected by a subject’s midline that corresponded to 75% correct discrimination. MAAs were 4.7°, 3.6°, and 4.2° for the northern elephant seal, harbor seal, and California sea lion, respectively. These results demonstrate that individuals of these Pinniped species have sound localization abilities comparable to the domestic cat and rhesus macaque. The acuity differences between our subjects were small and not predicted by head size. These results likely reflect the relatively acute general abilities of Pinnipeds to localize aerial broadband signals.

  • Localization of aerial broadband noise by Pinnipeds.
    The Journal of the Acoustical Society of America, 2004
    Co-Authors: Marla M Holt, Ronald J Schusterman, Brandon L Southall, David Kastak
    Abstract:

    Although many Pinnipeds (seals, sea lions, and walruses) emit broadband calls on land as part of their communication system, few studies have addressed these animals' ability to localize aerial broadband sounds. In this study, the aerial sound localization acuities of a female northern elephant seal (Mirounga angustirostris), a male harbor seal (Phoca vitulina), and a female California sea lion (Zalophus californianus) were measured in the horizontal plane. The stimulus was broadband white noise that was band pass filtered between 1.2 and 15 kHz. Testing was conducted in a hemi-anechoic chamber using a left/right forced choice procedure to measure the minimum audible angle (MAA) for each subject. MAAs were defined as half the angular separation of two sound sources bisected by a subject's midline that corresponded to 75% correct discrimination. MAAs were 4.7 degrees, 3.6 degrees, and 4.2 degrees for the northern elephant seal, harbor seal, and California sea lion, respectively. These results demonstrate that individuals of these Pinniped species have sound localization abilities comparable to the domestic cat and rhesus macaque. The acuity differences between our subjects were small and not predicted by head size. These results likely reflect the relatively acute general abilities of Pinnipeds to localize aerial broadband signals.

Bjorn K Van Der Leeuw - One of the best experts on this subject based on the ideXlab platform.

Annalisa Berta - One of the best experts on this subject based on the ideXlab platform.

  • The Origin and Evolutionary Biology of Pinnipeds: Seals, Sea Lions, and Walruses
    Annual Review of Earth and Planetary Sciences, 2018
    Co-Authors: Annalisa Berta, Morgan Churchill, Robert W. Boessenecker
    Abstract:

    The oldest definitive Pinniped fossils date from approximately 30.6–23 million years ago (Ma) in the North Pacific. Pinniped monophyly is consistently supported; the group shares a common ancestry with arctoid carnivorans, either ursids or musteloids. Crown Pinnipeds comprise the Otariidae (fur seals and sea lions), Odobenidae (walruses), and Phocidae (seals), with paraphyletic “enaliarctines” falling outside the crown group. The position of extinct Desmatophocidae is debated; they are considered to be closely related to both otariids and odobenids or, alternatively, to phocids. Both otariids and odobenids are known from the North Pacific, diverging approximately 19 Ma, with phocids originating in the North Atlantic or Paratethys region 19–14 Ma. Our understanding of Pinniped paleobiology has been enriched by studies that incorporate anatomical and behavioral data into a phylogenetic framework. There is now evidence for sexual dimorphism in the earliest Pinnipeds, heralding polygynous breeding systems, fo...

  • Chapter 3 – Pinniped Evolution and Systematics
    Marine Mammals, 2015
    Co-Authors: Annalisa Berta
    Abstract:

    Pinnipeds (seals, sea lions, and walruses) are defined as a monophyletic lineage using anatomical characters. The affinities, origin, and diversification of both stem and crown Pinnipeds are reviewed. Controversies regarding their relationship to other carnivores, the relationships among various Pinniped lineages, and the alliance of an extinct Pinniped clade, the desmatophocids, are also considered.

  • Pinniped taxonomy: review of currently recognized species and subspecies, and evidence used for their description
    Mammal Review, 2011
    Co-Authors: Annalisa Berta, Morgan Churchill
    Abstract:

    Pinnipeds are charismatic but difficult to study, and taxonomy is poorly under- stood. An accurate taxonomic framework is essential for studies of biogeography, ecology and conservation. 2. Morphologic and genetic criteria used to recognize Pinniped species and subspe- cies are evaluated individually for all taxa in the three families: Otariidae (sea lions and fur seals), Odobenidae (walruses) and Phocidae (seals). We advocate a pragmatic approach that, in general, follows the Evolutionary Species Concept and 'diagnos- ability' criterion for subspecies delimitations. 3. Of the 33 species, all have at least two lines of evidence to distinguish them, and of the 29 subspecies, 24 have at least one line of evidence, but five have inadequate support. We present a composite phylogeny for Pinnipeds. 4. We propose that the genus Arctocephalus be limited to Arctocephalus pusillus, and we resurrect the name Arctophoca for at least six species and subspecies. 5. We recommend large sample sizes and broad, random sampling in further research on Pinniped taxonomy. Taxa should be described based on robust statistical analysis, not by arbitrary division of characters, and molecular research should include analysis of mtDNA and nuDNA. 6. Finally, we offer suggestions for further taxonomic research (on hybridization in otariids, and to allow consideration of life history data in sampling) in an effort to improve our understanding of Pinniped diversity. Even for taxa which are already protected, better understanding of their taxonomy can only enhance their conser- vation status and facilitate efforts to protect their habitats.

  • Pinniped Evolution and Systematics
    Marine Mammals, 2006
    Co-Authors: Annalisa Berta, Kit M. Kovacs, James L. Sumich, Pieter Arend Folkens, Peter J. Adam
    Abstract:

    This chapter explores the understanding of Pinniped origin, diversification, and morphology. Characters defining the major groups of Pinnipeds are listed for reference. The chapter also considers controversies regarding the relationship of Pinnipeds to other carnivores; relationships among Pinnipeds; and the alliance of an extinct Pinniped group, desmatophocids. Modern Pinnipeds are aquatic members of the mammalian order Carnivora and comprise three monophyletic families: the Otariidae, the Odobenidae, and the Phocidae. All recent workers, on the basis of both molecular and morphologic data, agree that the closest relatives of Pinnipeds are arctoid carnivores, which include procyonids, mustelids, and ursids, although which specific arctoid group forms the closest alliance with Pinnipeds is still disputed. Although both morphological and molecular data support Pinniped monophyly, there is still disagreement on the relationships among Pinnipeds. Most of the controversy lies in the debate on whether the walrus is most closely related to phocids or to otariids. Two monophyletic lineages of walruses are recognized. The last Pinniped lineages to appear in the fossil record—the otariids—are only known as far back as 11 Ma in the North Pacific. Morphologic data support monophyly of the sea lions but not of the fur seals. Molecular data indicate that both fur seals and sea lions are paraphyletic.