Juvenile Bristol Bay Sockeye Salmon Ecology
Dissertation (Ph.D.) University of Alaska Fairbanks, 2008 Predicting annual returns of Bristol Bay sockeye salmon (Oncorhynchus nerka) has been difficult due to large, unexplained variations in return strength. Ocean conditions, particularly during the first few months after salmon leave freshwater,...
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ftunivalaska:oai:scholarworks.alaska.edu:11122/8948 2023-05-15T15:43:37+02:00 Juvenile Bristol Bay Sockeye Salmon Ecology Farley, Edward V., Jr. Adkison, Milo 2008 http://hdl.handle.net/11122/8948 unknown http://hdl.handle.net/11122/8948 Fisheries Division Aquatic sciences Ecology Biological oceanography Dissertation phd 2008 ftunivalaska 2023-02-23T21:37:09Z Dissertation (Ph.D.) University of Alaska Fairbanks, 2008 Predicting annual returns of Bristol Bay sockeye salmon (Oncorhynchus nerka) has been difficult due to large, unexplained variations in return strength. Ocean conditions, particularly during the first few months after salmon leave freshwater, are believed to have a strong influence on their early marine growth and survival. Limited historical and present research suggests that sea temperature can affect juvenile Bristol Bay distribution. During years with cool spring sea temperatures, juvenile sockeye salmon are distributed nearshore along the Alaska Peninsula, whereas they are found further offshore during years with warm spring sea temperatures. Juvenile sockeye salmon are larger, in better condition, and have higher marine stage survival after the first year at sea when they are distributed further offshore than when they are distributed nearshore along the Alaska Peninsula. Juvenile sockeye salmon stomach contents also shift from primarily Pacific sand lance ( Ammodytes hexapterus) and euphausiids to age 0 walleye pollock ( Theragra chalcogramma) when their distribution changes from nearshore to further offshore. Annual averages of juvenile sockeye salmon growth rate potential (GRP) were generally lower among years and regions with cool spring sea temperatures. In addition, juvenile sockeye salmon GRP was generally higher in offshore regions than nearshore regions of the eastern Bering Sea shelf. A sensitivity analysis indicated that juvenile sockeye salmon GRP was more sensitive to changes in observed (August to September) sea surface temperatures during years when prey densities were lower. The results of the dissertation suggest that variability in early marine survival is primarily due to bottom-up control of the trophic structure of the eastern Bering Sea ecosystem. Doctoral or Postdoctoral Thesis Bering Sea Theragra chalcogramma Alaska University of Alaska: ScholarWorks@UA Bering Sea Fairbanks Pacific Sockeye ENVELOPE(-130.143,-130.143,54.160,54.160) |
institution |
Open Polar |
collection |
University of Alaska: ScholarWorks@UA |
op_collection_id |
ftunivalaska |
language |
unknown |
topic |
Aquatic sciences Ecology Biological oceanography |
spellingShingle |
Aquatic sciences Ecology Biological oceanography Farley, Edward V., Jr. Juvenile Bristol Bay Sockeye Salmon Ecology |
topic_facet |
Aquatic sciences Ecology Biological oceanography |
description |
Dissertation (Ph.D.) University of Alaska Fairbanks, 2008 Predicting annual returns of Bristol Bay sockeye salmon (Oncorhynchus nerka) has been difficult due to large, unexplained variations in return strength. Ocean conditions, particularly during the first few months after salmon leave freshwater, are believed to have a strong influence on their early marine growth and survival. Limited historical and present research suggests that sea temperature can affect juvenile Bristol Bay distribution. During years with cool spring sea temperatures, juvenile sockeye salmon are distributed nearshore along the Alaska Peninsula, whereas they are found further offshore during years with warm spring sea temperatures. Juvenile sockeye salmon are larger, in better condition, and have higher marine stage survival after the first year at sea when they are distributed further offshore than when they are distributed nearshore along the Alaska Peninsula. Juvenile sockeye salmon stomach contents also shift from primarily Pacific sand lance ( Ammodytes hexapterus) and euphausiids to age 0 walleye pollock ( Theragra chalcogramma) when their distribution changes from nearshore to further offshore. Annual averages of juvenile sockeye salmon growth rate potential (GRP) were generally lower among years and regions with cool spring sea temperatures. In addition, juvenile sockeye salmon GRP was generally higher in offshore regions than nearshore regions of the eastern Bering Sea shelf. A sensitivity analysis indicated that juvenile sockeye salmon GRP was more sensitive to changes in observed (August to September) sea surface temperatures during years when prey densities were lower. The results of the dissertation suggest that variability in early marine survival is primarily due to bottom-up control of the trophic structure of the eastern Bering Sea ecosystem. |
author2 |
Adkison, Milo |
format |
Doctoral or Postdoctoral Thesis |
author |
Farley, Edward V., Jr. |
author_facet |
Farley, Edward V., Jr. |
author_sort |
Farley, Edward V., Jr. |
title |
Juvenile Bristol Bay Sockeye Salmon Ecology |
title_short |
Juvenile Bristol Bay Sockeye Salmon Ecology |
title_full |
Juvenile Bristol Bay Sockeye Salmon Ecology |
title_fullStr |
Juvenile Bristol Bay Sockeye Salmon Ecology |
title_full_unstemmed |
Juvenile Bristol Bay Sockeye Salmon Ecology |
title_sort |
juvenile bristol bay sockeye salmon ecology |
publishDate |
2008 |
url |
http://hdl.handle.net/11122/8948 |
long_lat |
ENVELOPE(-130.143,-130.143,54.160,54.160) |
geographic |
Bering Sea Fairbanks Pacific Sockeye |
geographic_facet |
Bering Sea Fairbanks Pacific Sockeye |
genre |
Bering Sea Theragra chalcogramma Alaska |
genre_facet |
Bering Sea Theragra chalcogramma Alaska |
op_relation |
http://hdl.handle.net/11122/8948 Fisheries Division |
_version_ |
1766377806523006976 |