Biological and Physical Environmental Drivers of Diet Variation in Northern Fur Seals
ABSTRACT The eastern Bering is a productive high‐latitude ecosystem characterized by high interannual variability in physical environmental conditions that impact biological communities. We investigated how the diet composition of northern fur seals (Callorhinus ursinus) breeding on the Pribilof Isl...
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Wiley
2025-08-01
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| Series: | Ecology and Evolution |
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| Online Access: | https://doi.org/10.1002/ece3.71998 |
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| author | Elizabeth A. McHuron Jeremy T. Sterling Katie Luxa James Thorson Rod Towell Rolf R. Ream Tonya Zeppelin |
| author_facet | Elizabeth A. McHuron Jeremy T. Sterling Katie Luxa James Thorson Rod Towell Rolf R. Ream Tonya Zeppelin |
| author_sort | Elizabeth A. McHuron |
| collection | DOAJ |
| description | ABSTRACT The eastern Bering is a productive high‐latitude ecosystem characterized by high interannual variability in physical environmental conditions that impact biological communities. We investigated how the diet composition of northern fur seals (Callorhinus ursinus) breeding on the Pribilof Islands was influenced by this variation, focusing on water temperatures (surface and bottom) and an index of walleye pollock abundance within foraging areas. We also explored whether interannual variation in diet composition influenced fur seal pup mortality rates or body mass. The frequency of occurrence (FO) of all eight fur seal prey groups detected from hard parts analysis of samples collected from 1987 to 2012 was affected by interannual variation in at least one of the three environmental variables. Pollock was the predominant prey group across the study years, highlighting the importance of this species to Pribilof Island fur seals. Not only was pollock consumed more frequently as it became more abundant within fur seal foraging areas, but its relative abundance also affected how frequently other prey groups were consumed. A considerable amount of variation in FO of almost all prey groups was explained by year effects, suggesting that water temperatures alone were not sufficiently capturing the influences of regional and local physical environmental conditions on prey availability for fur seals. The summed FO of non‐pollock prey groups had a small but detectable effect on the mass of male pups, indicating that the availability of prey groups beyond just pollock is somewhat beneficial for female northern fur seals early in lactation. Our results suggest that projected environmental changes in the eastern Bering Sea are likely to influence fur seal diets, but predicting the magnitude and direction of such changes is hampered until the underlying drivers of the observed temporal trends are better resolved. |
| format | Article |
| id | doaj-art-3d5bd8baf36a420a855b06fd3190af44 |
| institution | Kabale University |
| issn | 2045-7758 |
| language | English |
| publishDate | 2025-08-01 |
| publisher | Wiley |
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| series | Ecology and Evolution |
| spelling | doaj-art-3d5bd8baf36a420a855b06fd3190af442025-08-20T03:47:13ZengWileyEcology and Evolution2045-77582025-08-01158n/an/a10.1002/ece3.71998Biological and Physical Environmental Drivers of Diet Variation in Northern Fur SealsElizabeth A. McHuron0Jeremy T. Sterling1Katie Luxa2James Thorson3Rod Towell4Rolf R. Ream5Tonya Zeppelin6Cooperative Institute for Climate, Ocean, and Ecosystem Studies University of Washington Seattle Washington USAMarine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration Seattle Washington USAMarine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration Seattle Washington USAResource Ecology and Fisheries Management, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration Seattle Washington USAMarine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration Seattle Washington USAMarine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration Seattle Washington USAMarine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration Seattle Washington USAABSTRACT The eastern Bering is a productive high‐latitude ecosystem characterized by high interannual variability in physical environmental conditions that impact biological communities. We investigated how the diet composition of northern fur seals (Callorhinus ursinus) breeding on the Pribilof Islands was influenced by this variation, focusing on water temperatures (surface and bottom) and an index of walleye pollock abundance within foraging areas. We also explored whether interannual variation in diet composition influenced fur seal pup mortality rates or body mass. The frequency of occurrence (FO) of all eight fur seal prey groups detected from hard parts analysis of samples collected from 1987 to 2012 was affected by interannual variation in at least one of the three environmental variables. Pollock was the predominant prey group across the study years, highlighting the importance of this species to Pribilof Island fur seals. Not only was pollock consumed more frequently as it became more abundant within fur seal foraging areas, but its relative abundance also affected how frequently other prey groups were consumed. A considerable amount of variation in FO of almost all prey groups was explained by year effects, suggesting that water temperatures alone were not sufficiently capturing the influences of regional and local physical environmental conditions on prey availability for fur seals. The summed FO of non‐pollock prey groups had a small but detectable effect on the mass of male pups, indicating that the availability of prey groups beyond just pollock is somewhat beneficial for female northern fur seals early in lactation. Our results suggest that projected environmental changes in the eastern Bering Sea are likely to influence fur seal diets, but predicting the magnitude and direction of such changes is hampered until the underlying drivers of the observed temporal trends are better resolved.https://doi.org/10.1002/ece3.71998Bering SeaCallorhinus ursinusfrequency of occurrencelaaqudanPribilof Islands |
| spellingShingle | Elizabeth A. McHuron Jeremy T. Sterling Katie Luxa James Thorson Rod Towell Rolf R. Ream Tonya Zeppelin Biological and Physical Environmental Drivers of Diet Variation in Northern Fur Seals Ecology and Evolution Bering Sea Callorhinus ursinus frequency of occurrence laaqudan Pribilof Islands |
| title | Biological and Physical Environmental Drivers of Diet Variation in Northern Fur Seals |
| title_full | Biological and Physical Environmental Drivers of Diet Variation in Northern Fur Seals |
| title_fullStr | Biological and Physical Environmental Drivers of Diet Variation in Northern Fur Seals |
| title_full_unstemmed | Biological and Physical Environmental Drivers of Diet Variation in Northern Fur Seals |
| title_short | Biological and Physical Environmental Drivers of Diet Variation in Northern Fur Seals |
| title_sort | biological and physical environmental drivers of diet variation in northern fur seals |
| topic | Bering Sea Callorhinus ursinus frequency of occurrence laaqudan Pribilof Islands |
| url | https://doi.org/10.1002/ece3.71998 |
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