Changes in Size and Age of Chinook Salmon Oncorhynchus tshawytscha Returning to Alaska.
The average sizes of Pacific salmon have declined in some areas in the Northeast Pacific over the past few decades, but the extent and geographic distribution of these declines in Alaska is uncertain. Here, we used regression analyses to quantify decadal trends in length and age at maturity in ten d...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2015-01-01
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| Series: | PLoS ONE |
| Online Access: | http://europepmc.org/articles/PMC4474552?pdf=render |
| _version_ | 1819074214159712256 |
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| author | Bert Lewis W Stewart Grant Richard E Brenner Toshihide Hamazaki |
| author_facet | Bert Lewis W Stewart Grant Richard E Brenner Toshihide Hamazaki |
| author_sort | Bert Lewis |
| collection | DOAJ |
| description | The average sizes of Pacific salmon have declined in some areas in the Northeast Pacific over the past few decades, but the extent and geographic distribution of these declines in Alaska is uncertain. Here, we used regression analyses to quantify decadal trends in length and age at maturity in ten datasets from commercial harvests, weirs, and spawner abundance surveys of Chinook salmon Oncorhynchus tshawytscha throughout Alaska. We found that on average these fish have become smaller over the past 30 years (~6 generations), because of a decline in the predominant age at maturity and because of a decrease in age-specific length. The proportion of older and larger 4-ocean age fish in the population declined significantly (P < 0.05) in all stocks examined by return year or brood year. Our analyses also indicated that the age-specific lengths of 4-ocean fish (9 of 10 stocks) and of 3-ocean fish (5 of 10 stocks) have declined significantly (P < 0.05). Size-selective harvest may be driving earlier maturation and declines in size, but the evidence is not conclusive, and additional factors, such as ocean conditions or competitive interactions with other species of salmon, may also be responsible. Regardless of the cause, these wide-spread phenotypic shifts influence fecundity and population abundance, and ultimately may put populations and associated fisheries at risk of decline. |
| first_indexed | 2024-12-21T18:05:57Z |
| format | Article |
| id | doaj.art-9cf8bde37e924a62831654a92163c144 |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-12-21T18:05:57Z |
| publishDate | 2015-01-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS ONE |
| spelling | doaj.art-9cf8bde37e924a62831654a92163c1442022-12-21T18:54:56ZengPublic Library of Science (PLoS)PLoS ONE1932-62032015-01-01106e013018410.1371/journal.pone.0130184Changes in Size and Age of Chinook Salmon Oncorhynchus tshawytscha Returning to Alaska.Bert LewisW Stewart GrantRichard E BrennerToshihide HamazakiThe average sizes of Pacific salmon have declined in some areas in the Northeast Pacific over the past few decades, but the extent and geographic distribution of these declines in Alaska is uncertain. Here, we used regression analyses to quantify decadal trends in length and age at maturity in ten datasets from commercial harvests, weirs, and spawner abundance surveys of Chinook salmon Oncorhynchus tshawytscha throughout Alaska. We found that on average these fish have become smaller over the past 30 years (~6 generations), because of a decline in the predominant age at maturity and because of a decrease in age-specific length. The proportion of older and larger 4-ocean age fish in the population declined significantly (P < 0.05) in all stocks examined by return year or brood year. Our analyses also indicated that the age-specific lengths of 4-ocean fish (9 of 10 stocks) and of 3-ocean fish (5 of 10 stocks) have declined significantly (P < 0.05). Size-selective harvest may be driving earlier maturation and declines in size, but the evidence is not conclusive, and additional factors, such as ocean conditions or competitive interactions with other species of salmon, may also be responsible. Regardless of the cause, these wide-spread phenotypic shifts influence fecundity and population abundance, and ultimately may put populations and associated fisheries at risk of decline.http://europepmc.org/articles/PMC4474552?pdf=render |
| spellingShingle | Bert Lewis W Stewart Grant Richard E Brenner Toshihide Hamazaki Changes in Size and Age of Chinook Salmon Oncorhynchus tshawytscha Returning to Alaska. PLoS ONE |
| title | Changes in Size and Age of Chinook Salmon Oncorhynchus tshawytscha Returning to Alaska. |
| title_full | Changes in Size and Age of Chinook Salmon Oncorhynchus tshawytscha Returning to Alaska. |
| title_fullStr | Changes in Size and Age of Chinook Salmon Oncorhynchus tshawytscha Returning to Alaska. |
| title_full_unstemmed | Changes in Size and Age of Chinook Salmon Oncorhynchus tshawytscha Returning to Alaska. |
| title_short | Changes in Size and Age of Chinook Salmon Oncorhynchus tshawytscha Returning to Alaska. |
| title_sort | changes in size and age of chinook salmon oncorhynchus tshawytscha returning to alaska |
| url | http://europepmc.org/articles/PMC4474552?pdf=render |
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