Influences on fecundity in Australian fur seals (Arctocephalus pusillus doriferus)

Gibbens, J.; Parry, Laura J.; Arnould, John P. Y.

doi:10.1644/08-mamm-a-377.1

Cited by 31 publications

(32 citation statements)

References 38 publications

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“…Natality of 55% or lower has been associated with declining populations of otariids and related to the adverse effects of density dependant factors such as intraspecific competition for food or breeding space [6], [42] but see also [43]. Therefore, our estimate of natality from the Chiswell Island population of Steller sea lions is indicative of a population where adult females seemingly are not under resource limitation.…”

Section: Discussionmentioning

confidence: 97%

A Longitudinal Study of Steller Sea Lion Natality Rates in the Gulf of Alaska with Comparisons to Census Data

et al. 2014

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Steller sea lion (Eumetopias jubatus) numbers in the Western Distinct Population Segment are beginning to recover following the dramatic decline that began in the 1970s and ended around the turn of the century. Low female reproductive rates (natality) may have contributed to the decline and remain an issue of concern for this population. During the 2000s we found high natality among Steller sea lions in the Gulf of Alaska indicating a healthy population. This study extends these previous estimates over an additional three years and tests for interannual variations and long-term trends. We further examine the proportions of pups to adult females observed on the rookery and nearby haulouts during the birthing season to assess whether census data can be used to estimate natality. Open robust design multistate models were built and tested using Program MARK to estimate survival, resighting, and state transition probabilities in addition to other parameters dependent on whether or not a female gave birth in the previous year. Natality was estimated at 70% with some evidence of interannual variation but a long-term increasing or decreasing trend was not supported by the data. Bootstrap and regression comparisons of census data with natality estimates revealed no correlation between the two methods suggesting that census data are not an appropriate proxy for natality in this species. Longitudinal studies of individual animals are an appropriate method for estimating vital rates in species with variable detection over time such as the Steller sea lion. This work indicates that natality remains high in this region and is consistent with a population in recovery.

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Section: Discussionmentioning

confidence: 97%

A Longitudinal Study of Steller Sea Lion Natality Rates in the Gulf of Alaska with Comparisons to Census Data

et al. 2014

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“…Together, these colonies account for 24% of the total species population (Kirkwood et al 2010). The samples were collected opportunistically during other concurrent studies (Arnould & Hindell 2001, Littnan 2003, Gibbens et al 2010.…”

Section: Methodsmentioning

confidence: 99%

“…To investigate the potential impact of pregnancy on isotope values, aliquots of the 2003 to 2005 plasma samples were also assayed using coated-tube radioimmunoassay kits (Spectria, Progesterone RIA, Orion Diagnostica) for progesterone concentration to determine pregnancy status as described by Gibbens et al (2010). Briefly, the organic component of each sample of plasma was extracted with ethyl acetate, then resuspended in water to achieve a 1:4 dilution.…”

Section: Methodsmentioning

confidence: 99%

Stable isotopes reveal inter-annual and inter-individual variation in the diet of female Australian fur seals

Arnould¹,

Cherel²,

Gibbens³

et al. 2011

Mar. Ecol. Prog. Ser.

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“…12 Rates of gestational failure have been estimated in only a few pinniped species. Annually, up to 20% of Californian sea lion pups on San Miguel Island, California, are either aborted or born prematurely and die soon after.…”

Section: Discussionmentioning

confidence: 99%

“…22,35 Low fecundity resulting from a high incidence of spontaneous abortions in the second half of gestation is a major contributory factor to the slow population growth in the Australian fur seal. 12 ). Sampling for this project was conducted concurrently with other research studies to limit disturbance to the colonies.…”

Section: Introductionmentioning

confidence: 99%

Mycoplasmas in Australian fur seals (Arctocephalus pusillus doriferus): identification and association with abortion

et al. 2011

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Abstract. Bacteria from the genus Mycoplasma are common inhabitants of the respiratory, gastrointestinal, and genital tracts of mammals. The understanding of the pathological significance of mycoplasmas in seals is poor, as few studies have utilized the specific culture techniques required to isolate these bacteria. The current study surveyed for the Mycoplasma species present in Australian fur seals (Arctocephalus pusillus doriferus) and investigated the association between infection and pathology. Mycoplasmas were found in the nasal cavities of 55/80 (69%) of apparently healthy individuals. Isolates from 18 individuals were investigated through 16S ribosomal RNA sequencing, and 3 species were identified: M. zalophi, M. phocae, and Mycoplasma sp. (GenBank no. EU714238.1), all of which had previously been isolated from Northern Hemisphere pinnipeds. In addition, mycoplasmas were isolated from the lungs of 4 out of 16 juveniles and 1 out of 5 adults sampled at necropsy. Isolates obtained were M. zalophi, Mycoplasma sp. EU714238.1, and M. phocicerebrale, but infection was not associated with lung pathology in these age classes. Inflammatory disease processes of the heart and/or lungs were present in 12 out of 32 (38%) aborted fetuses on microscopic examination. Predominant findings were interstitial pneumonia, pericarditis, and myocarditis. Mycoplasma phocicerebrale was isolated from the thymus of an aborted fetus, and 3 out of 11 (27%) fetuses with inflammatory heart or lung lesions were PCR-positive for Mycoplasma. In conclusion, several species of Mycoplasma are part of the normal flora of the nasal cavity of Australian fur seals, and some mycoplasmas may be associated with abortion in this species of seal.

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Influences on fecundity in Australian fur seals (Arctocephalus pusillus doriferus)

Cited by 31 publications

References 38 publications

A Longitudinal Study of Steller Sea Lion Natality Rates in the Gulf of Alaska with Comparisons to Census Data

A Longitudinal Study of Steller Sea Lion Natality Rates in the Gulf of Alaska with Comparisons to Census Data

Stable isotopes reveal inter-annual and inter-individual variation in the diet of female Australian fur seals

Mycoplasmas in Australian fur seals (Arctocephalus pusillus doriferus): identification and association with abortion

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