Author: R. CARRICKPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Studies on the southern elephant seal, Mirounga leonina (L.). V. Population dynamics and utilization
Author: R. CARRICKElephant Seals
Author: Burney J. Le BeoufPublisher: Univ of California Press
ISBN: 0520368177
Category : Nature
Languages : en
Pages : 434
Book Description
The largest of all seals, elephant seals rank among the most impressive of marine mammals. They are renowned for their spectacular recovery from near-extinction at the end of the nineteenth century when seal hunters nearly eliminated the entire northern species. No other vertebrate has come so close to extinction and made such a complete recovery. The physiological extremes that elephant seals can tolerate are also remarkable: females fast for a month while lactating, and the largest breeding males fast for over one hundred days during the breeding seasons, at which times both sexes lose forty percent of their body weight. Elephant seals dive constantly during their long foraging migrations, spending more time under water than most whales and diving deeper and longer than any other marine mammal. This first book-length discussion of elephant seals brings together worldwide expertise from scientists who describe and debate recent research, including the history and status of various populations, their life-history tactics, and other findings obtained with the help of modern microcomputer diving instruments attached to free-ranging seals. Essential for all marine mammalogists for its information and its methodological innovations, Elephant Seals will also illuminate current debates about species extinctions and possible means of preventing them. This title is part of UC Press's Voices Revived program, which commemorates University of California Press’s mission to seek out and cultivate the brightest minds and give them voice, reach, and impact. Drawing on a backlist dating to 1893, Voices Revived makes high-quality, peer-reviewed scholarship accessible once again using print-on-demand technology. This title was originally published in 1994.
Elephant Seals
Author: Burney J. Le BeoufPublisher: Univ of California Press
ISBN: 0520328159
Category : Science
Languages : en
Pages : 434
Book Description
The largest of all seals, elephant seals rank among the most impressive of marine mammals. They are renowned for their spectacular recovery from near-extinction at the end of the nineteenth century when seal hunters nearly eliminated the entire northern species. No other vertebrate has come so close to extinction and made such a complete recovery. The physiological extremes that elephant seals can tolerate are also remarkable: females fast for a month while lactating, and the largest breeding males fast for over one hundred days during the breeding seasons, at which times both sexes lose forty percent of their body weight. Elephant seals dive constantly during their long foraging migrations, spending more time under water than most whales and diving deeper and longer than any other marine mammal. This first book-length discussion of elephant seals brings together worldwide expertise from scientists who describe and debate recent research, including the history and status of various populations, their life-history tactics, and other findings obtained with the help of modern microcomputer diving instruments attached to free-ranging seals. Essential for all marine mammalogists for its information and its methodological innovations, Elephant Seals will also illuminate current debates about species extinctions and possible means of preventing them. This title is part of UC Press's Voices Revived program, which commemorates University of California Press’s mission to seek out and cultivate the brightest minds and give them voice, reach, and impact. Drawing on a backlist dating to 1893, Voices Revived makes high-quality, peer-reviewed scholarship accessible once again using print-on-demand technology. This title was originally published in 1994.
Analysis of Foraging Behavior of the Southern Elephant Seal (Mirounga Leonina) in Its Observed and Simulated Oceanic Physical and Biological Environment
Author: Yves Le BrasPublisher:
ISBN:
Category :
Languages : en
Pages : 32
Book Description
Although the information about the abundance and the distribution of mid-trophic level organisms would have a great interest in the general context of ecological research and multi-species fisheries management, the sampling of mid-trophic level organisms is expensive and biase and such information is not avalaible. For the study of distribution, habitats and foraging ecology of top predators, MTL biomass would be a highly valuable explaining variable. In this context, the modelling of the spatial dynamics of MTL biomass appears to be a useful tool but the quality of predictions can't be easily evaluated. This study aimed at using bio-logging data of Southern elephant seals of the Kerguelen Island to evaluate some key aspects of the modelling approach of SEAPODYM micronekton model. The use of prey catch attempts counting (derived from accelerometry) allowed to validate : the use of the euphotic depth as a way to describe the vertical distribution of the micronekton, the choice of layer's definition and provided encouraging results relatively to the quantitative predictions of micronekton biomass. Then, the predictions of this model were used in parallel with two different proxies of the foraging activity of the Southern elephant seals to investigate the feeding behaviour in an environment charactyerized by th mesoscale activity.
An analysis of the southern elephant seal Mirounga leonina breeding population at Kerguelen
Author: M.N. BESTERLife History Studies of the Southern Elephant Seal Population at Marion Island
Author: P. J. Nico De BruynPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Holistic studies of mammalian life history factors and their consequences on population demography require an intensive, multifaceted field methodology and effort over long temporal scales. A 25-year longitudinal mark-recapture experiment on southern elephant seals, Mirounga leonina, at Subantarctic Marion Island provide such a foundation for demographic analyses and relevant methodology advancement. Two gaps in the methodology related to life history and population demographic research are, the absence of large samples of known mass individuals, and an inability to identify mother-pup relatedness. A novel three-dimensional photogrammetric technique is designed here that allows for mass estimation of large samples of southern elephant seals in the field. An effective temporary marking technique for unweaned pups is implemented that allows for identification of large samples of pups with known mothers prior to the maternal bond being severed at weaning. These known pups can then be marked with more robust tags and relatedness information is preserved long-term. Thus, mass estimates can now be applied as covariates in modelling analyses to address questions of, for example, maternal investment, kinship associated behaviour, and the consequences thereof on survival and reproductive parameters. The state change in the Marion Island southern elephant seal population from decrease to stabilisation/increase is shown to have resulted from improved survivorship in both juvenile and adult female age classes. Male seals of all ages did not indicate improved survivorship following the period of decline. The inflexion in survivorship is identified as 1994, whence improved survivorship of juvenile seals preceded that of young adult females. This inflexion in survivorship is postulated to have resulted in a population trend inflexion around 1998. Female southern elephant seals do not show evidence of actuarial senescence, but reproductive senescence is apparent after 12 years of age. A longterm reproductive cost (reduced breeding effort) is associated with early primiparity (age three) as compared with later primiparity (4- 5- or 6-year-old). The mean proportion of 3-year-old breeders has not increased after 1994 as has been hypothesized in previous studies. Contrary to previous assumptions, females do not as a rule breed every year. Annually interrupted breeding efforts are more common than consecutive breeding efforts. No difference in the proportions of interrupted versus uninterrupted breeding efforts was identified between periods of population decline and stabilisation/increase. Longevity as predicted by survival estimates exceeds the observed frequencies. This study provides unique longevity and fertility schedules for the species. The improved survivorship, reproductive senescence and breeding schedules of female southern elephant seals in this population provide groundwork for reevaluation of previous studies and their conclusions. The addition of relatedness and body condition information will allow for sophisticated multistate modelling of population demography in future studies. However, analytical procedures and techniques employed need to be meticulously designed and thoroughly thought through to avoid mis-interpretation of biological data. In addition to a multistate single species analytical approach, the importance of an ecosystem approach to species population demographic studies is highlighted through the augmenting of data on relevant potential drivers of population change, such as killer whales, Orcinus orca.
Study of the Biology of the Southern Elephant Seal, Mirounga Leonina (Linn.)
Author: Michael MacLaren BrydenCurrent Mammalogy
Author: H.H. GenowaysPublisher: Springer Science & Business Media
ISBN: 1475799098
Category : Science
Languages : en
Pages : 530
Book Description
When I first proposed a series entitled Current Mammalogy to the pub lishers, they were reluctant to undertake such a project because they viewed the field of mammology as overly fragmented. At first I found this idea to be difficult to accept; however, upon reflection, I came near to agreeing with it. Although many of us work on mammals, we gen erally feel more allegiance to our specialties, such as systematics, ge netics, cytogenetics, ecology, behavior, pest control, paleontology, wildlife management, primatology, and marine mammalogy, than we do to the general field of mammalogy. However, rather than becoming discour aged from pursuing this project, I became more certain than ever that a series such as Current Mammalogy was needed. We hope to make this series a place where specialists can present their ideas not only to other members of their specialty, but to those outside the area as well. Hopefully, this exchange of ideas will be a mutually beneficial exercise. The Editorial Board of Current Mammalogy has decided to keep the range of subjects in each volume as broad as possible rather than concentrating on one or two topics, in the hope that this will keep the series as useful as possible to the broadest range of readers.
Author: R. CARRICK
Author: R. CARRICK