Foraging differences and early maternal investment in adult female Alaskan Steller sea lions (Eumetopias jubatus) /
For lactating Steller sea lions (SSLs), access to sufficient food within close proximity to the rookery is essential for milk production and successful pup rearing. Food limitation has been suggested as a cause of the SSL decline, which has been ongoing since the 1970s. The severity of the decline...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2000.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=728408361&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | For lactating Steller sea lions (SSLs), access to sufficient food within close proximity to the rookery is essential for milk production and successful pup rearing. Food limitation has been suggested as a cause of the SSL decline, which has been ongoing since the 1970s. The severity of the decline has resulted in SSLs being listed as threatened in the eastern portion of their range and endangered in the western region. This study compared the proximate composition of milk, and milk and energy intake rates of pups during the first month postpartum between regions of stable and declining population. Feeding preferences of adult females were also examined using fatty acid profiles of their milk and blubber. The proximate composition of milk did not differ significantly among regions, except for total protein. Milk averaged 61.8 ± 7.13% water, 21.6 ± 5.70% lipid, 9.3 ± 1.89% protein, and 2.2 ± 0.73% ash. The difference in total protein did not significantly affect energy content, which averaged 10.2 ± 2.31 kJ·ml⁻¹. Energy intake rates of pups did not differ among regions, averaging 733.2 ± 117.37 kJ·kg⁻¹·d⁻¹. However, estimated maintenance requirements for milk energy of pups in the region of stable population were over twice that of pups in the region of population decline. Daily growth rates of pups in the region of stable population were slower than those of pups in the region of population decline. Fatty acid profile analyses indicated both spatial and temporal differences in the diets of lactating SSLs that may reflect the abundance and diversity of prey in various geographic regions. The results also indicated that winter and summer foraging ranges or prey preferences of adult female SSLs are sufficiently distinct between metapopulations to allow determination of geographic region from either milk or blubber fatty acids. While analyses of prey fatty acids are needed to determine species composition of diet, it appears that females in the region of stable population are consuming different prey compared with those in the area of population decline, and that this has had a significant effect on maternal investment during the first month postpartum. |
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| Item Description: | Vita. "Major Subject: Wildlife and Fisheries Sciences". |
| Physical Description: | xii, 151 leaves : illustrations, maps ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 128-144). |