Age‐specific reproduction in female Steller sea lions in Southeast Alaska
Abstract Age‐, region‐, and year‐specific estimates of reproduction are needed for monitoring wildlife populations during periods of ecosystem change. Population dynamics of Steller sea lions (Eumetopias jubatus) in Southeast Alaska varied regionally (with high population growth and survival in the...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2023-09-01
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| Series: | Ecology and Evolution |
| Subjects: | |
| Online Access: | https://doi.org/10.1002/ece3.10515 |
| _version_ | 1827698822982139904 |
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| author | Kelly K. Hastings Lauri A. Jemison Grey W. Pendleton Devin S. Johnson Thomas S. Gelatt |
| author_facet | Kelly K. Hastings Lauri A. Jemison Grey W. Pendleton Devin S. Johnson Thomas S. Gelatt |
| author_sort | Kelly K. Hastings |
| collection | DOAJ |
| description | Abstract Age‐, region‐, and year‐specific estimates of reproduction are needed for monitoring wildlife populations during periods of ecosystem change. Population dynamics of Steller sea lions (Eumetopias jubatus) in Southeast Alaska varied regionally (with high population growth and survival in the north vs. the south) and annually (with reduced adult female survival observed following a severe marine heatwave event), but reproductive performance is currently unknown. We used mark‐resighting data from 1006 Steller sea lion females marked as pups at ~3 weeks of age from 1994 to 1995 and from 2001 to 2005 and resighted from 2002 to 2019 (to a maximum age of 25) to examine age‐, region‐, and year‐specific reproduction. In the north versus the south, age of first reproduction was earlier (beginning at age 4 vs. age 5, respectively) but annual birth probabilities of parous females were reduced by 0.05. In an average year pre‐heatwave, the proportion of females with pup at the end of the pupping season peaked at ages 12–13 with ~0.60/0.65 (north/south) with pup, ~0.30/0.25 with juvenile, and ~0.10 (both regions) without a dependent. In both regions, reproductive senescence was gradual after age 12: ~0.40, 0.40, and 0.20 of females were in these reproductive states, respectively, by age 20. Correcting for neonatal mortality, true birth probabilities at peak ages were 0.66/0.72 (north/south). No cost of reproduction on female survival was detected, but pup production remained lower (−0.06) after the heatwave event, which if sustained could result in population decline in the south. Reduced pup production and greater retention of juveniles during periods of poor prey conditions may be an important strategy for Steller sea lions in Southeast Alaska, where fine‐tuning reproduction based on nutritional status may improve the lifetime probability of producing pups under good conditions in a variable and less productive environment. |
| first_indexed | 2024-03-10T13:36:30Z |
| format | Article |
| id | doaj.art-1f2917418e394e6fbc8efc6ad3e037d7 |
| institution | Directory Open Access Journal |
| issn | 2045-7758 |
| language | English |
| last_indexed | 2024-03-10T13:36:30Z |
| publishDate | 2023-09-01 |
| publisher | Wiley |
| record_format | Article |
| series | Ecology and Evolution |
| spelling | doaj.art-1f2917418e394e6fbc8efc6ad3e037d72023-11-21T07:26:25ZengWileyEcology and Evolution2045-77582023-09-01139n/an/a10.1002/ece3.10515Age‐specific reproduction in female Steller sea lions in Southeast AlaskaKelly K. Hastings0Lauri A. Jemison1Grey W. Pendleton2Devin S. Johnson3Thomas S. Gelatt4Alaska Department of Fish and Game Juneau Alaska USAAlaska Department of Fish and Game Juneau Alaska USAAlaska Department of Fish and Game Juneau Alaska USAProtected Resources Division, National Marine Fisheries Service Pacific Islands Fisheries Science Center Honolulu Hawaii USAMarine Mammal Laboratory, National Marine Fisheries Service Alaska Fisheries Science Center Seattle Washington USAAbstract Age‐, region‐, and year‐specific estimates of reproduction are needed for monitoring wildlife populations during periods of ecosystem change. Population dynamics of Steller sea lions (Eumetopias jubatus) in Southeast Alaska varied regionally (with high population growth and survival in the north vs. the south) and annually (with reduced adult female survival observed following a severe marine heatwave event), but reproductive performance is currently unknown. We used mark‐resighting data from 1006 Steller sea lion females marked as pups at ~3 weeks of age from 1994 to 1995 and from 2001 to 2005 and resighted from 2002 to 2019 (to a maximum age of 25) to examine age‐, region‐, and year‐specific reproduction. In the north versus the south, age of first reproduction was earlier (beginning at age 4 vs. age 5, respectively) but annual birth probabilities of parous females were reduced by 0.05. In an average year pre‐heatwave, the proportion of females with pup at the end of the pupping season peaked at ages 12–13 with ~0.60/0.65 (north/south) with pup, ~0.30/0.25 with juvenile, and ~0.10 (both regions) without a dependent. In both regions, reproductive senescence was gradual after age 12: ~0.40, 0.40, and 0.20 of females were in these reproductive states, respectively, by age 20. Correcting for neonatal mortality, true birth probabilities at peak ages were 0.66/0.72 (north/south). No cost of reproduction on female survival was detected, but pup production remained lower (−0.06) after the heatwave event, which if sustained could result in population decline in the south. Reduced pup production and greater retention of juveniles during periods of poor prey conditions may be an important strategy for Steller sea lions in Southeast Alaska, where fine‐tuning reproduction based on nutritional status may improve the lifetime probability of producing pups under good conditions in a variable and less productive environment.https://doi.org/10.1002/ece3.10515life historymarine heatwavemarine mammalnatalityotariidpinniped |
| spellingShingle | Kelly K. Hastings Lauri A. Jemison Grey W. Pendleton Devin S. Johnson Thomas S. Gelatt Age‐specific reproduction in female Steller sea lions in Southeast Alaska Ecology and Evolution life history marine heatwave marine mammal natality otariid pinniped |
| title | Age‐specific reproduction in female Steller sea lions in Southeast Alaska |
| title_full | Age‐specific reproduction in female Steller sea lions in Southeast Alaska |
| title_fullStr | Age‐specific reproduction in female Steller sea lions in Southeast Alaska |
| title_full_unstemmed | Age‐specific reproduction in female Steller sea lions in Southeast Alaska |
| title_short | Age‐specific reproduction in female Steller sea lions in Southeast Alaska |
| title_sort | age specific reproduction in female steller sea lions in southeast alaska |
| topic | life history marine heatwave marine mammal natality otariid pinniped |
| url | https://doi.org/10.1002/ece3.10515 |
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