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dc.contributor.authorLitz, Beate
dc.date.accessioned2022-03-23T18:55:26Z
dc.date.available2022-03-23T18:55:26Z
dc.date.issued2008-08
dc.identifier.urihttp://hdl.handle.net/11122/12832
dc.descriptionThesis (M.S.) University of Alaska Fairbanks, 2008en_US
dc.description.abstract"Steller sea lions (Eumetopias jubatus) have experienced a drastic population decline in the past several decades. Among hypotheses for the decline and failure of the population to recover is decreased reproductive success. Harsh environmental conditions within the species range and the large body size of the animals can limit sampling efforts to investigate these hypotheses. Three captive Steller sea lions were used as models to validate the use of fecal steroid analysis for this species. Their annual endocrine fluctuations were monitored over four years to gain a better understanding of their reproductive endocrinology and overcome sampling challenges typically associated with hormonal studies of large mammals. Radioimmunoassays (RIA) and enzyme immunoassays (EIA) reliably measured testosterone, total estrogens, and progesterone extracted from Steller sea lion feces. Lack of refrigeration for five days and freezing ( -20°C) for 8 weeks did not alter concentrations of fecal testosterone and total estrogens measured. The stability of fecal progesterone in the absence of cold storage was compromised by 4.5 days; however, it remained stable while frozen ( -20°C) for 8 weeks. Thus, for field research, there are two primary implications. Firstly, samples of freshly voided scat collected from rookeries and haulouts can reliably reflect hormone concentrations for <̲ 4.5 days and secondly, these samples can be stored for later analysis for at least 8 weeks. Long-term serial sampling demonstrated fecal progesterone may be more useful in providing information on reproductive function than fecal estrogens. Annual endocrine profiles suggest the females are seasonally monoestrus, supporting the general assumption for the species, and the male has a strong seasonal cycle in testosterone with maximum concentrations measured just prior to the natural breeding season. These data also suggest fecal testosterone reflects changes in testicular activity despite breeding status and proximity to females. Collectively, these data suggest this non-invasive endocrine monitoring technique has potential to provide a useful alternative method of sample collection"--Leaf iiien_US
dc.description.sponsorshipAlaska SeaLife Center Steller Sea Lion Programen_US
dc.language.isoen_USen_US
dc.subjectSteller's sea lionen_US
dc.subjectReproductionen_US
dc.subjectEndocrineen_US
dc.subjectSexual hormonesen_US
dc.subjectProgestational hormonesen_US
dc.subjectSteroid hormonesen_US
dc.subjectFecal analysisen_US
dc.titleCharacterization of reproductive cyclicity of sex steroids by fecal analysis in Steller sea lions (Eumetopias jubatus)en_US
dc.typeThesisen_US
dc.type.degreemsen_US
dc.identifier.departmentProgram in Marine Science and Limnologyen_US
refterms.dateFOA2022-03-23T18:55:26Z


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