Understanding Smolt Survival Trends in Sockeye Salmon
Many populations of Sockeye Salmon Oncorhynchus nerka in the eastern North Pacific Ocean experienced significant productivity declines that began about 1990, but there is no consensus on the mechanisms responsible. To better understand Sockeye Salmon survival trends, we examined the 50-year time ser...
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ftbioone:10.1080/19425120.2013.831002 2024-06-02T08:13:18+00:00 Understanding Smolt Survival Trends in Sockeye Salmon James R. Irvine James R. Irvine world 2013-01-01 text/HTML https://doi.org/10.1080/19425120.2013.831002 en eng American Fisheries Society doi:10.1080/19425120.2013.831002 All rights reserved. https://doi.org/10.1080/19425120.2013.831002 Text 2013 ftbioone https://doi.org/10.1080/19425120.2013.831002 2024-05-07T00:51:43Z Many populations of Sockeye Salmon Oncorhynchus nerka in the eastern North Pacific Ocean experienced significant productivity declines that began about 1990, but there is no consensus on the mechanisms responsible. To better understand Sockeye Salmon survival trends, we examined the 50-year time series for two age-classes of Sockeye Salmon smolts from Chilko Lake in central British Columbia. Arranging survival time series for both age-classes by ocean entry year and combining them, weighted by a proxy model of sampling variance, reduced the sampling variance in the original age-1 smolt survivals sufficiently to indicate a linear trend of increasing survival from 1960 to 1990 that suddenly changed at or near 1991 to a lower and declining trend from 1992 to 2008. Neither density nor mean length influenced smolt survival. Returns in a given year were not good predictors of siblings returning in subsequent years. Time spent at sea increased linearly beginning around 1970. Although smolt survivals differed between ecosystem regimes, there was only the one clear pattern break about 1991. To improve our understanding of mechanisms, survival trends were compared with environmental indices that included catches and hatchery releases of potentially competing salmon from around the North Pacific Ocean. Smolt survivals were more similar to abundance indices of Sockeye Salmon, Chum Salmon O. keta, and Pink Salmon O. gorbuscha than to indices of global, regional, or local ocean climate. Our results are consistent with the hypothesis that salmon productivity in the North Pacific declined soon after 1990. We present a simple model to illustrate how increased competition at sea, related to the release of large numbers of hatchery salmon, in conjunction with changes in ocean productivity, may have played a significant role in improving Sockeye Salmon survivals while reducing their growth before 1991. After 1991, these factors may have acted to reduce survivals while the growth of survivors showed no effect. Text Pink salmon BioOne Online Journals Keta ENVELOPE(-19.455,-19.455,65.656,65.656) Pacific Sockeye ENVELOPE(-130.143,-130.143,54.160,54.160) Marine and Coastal Fisheries 5 1 303 328 |
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Open Polar |
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BioOne Online Journals |
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ftbioone |
language |
English |
description |
Many populations of Sockeye Salmon Oncorhynchus nerka in the eastern North Pacific Ocean experienced significant productivity declines that began about 1990, but there is no consensus on the mechanisms responsible. To better understand Sockeye Salmon survival trends, we examined the 50-year time series for two age-classes of Sockeye Salmon smolts from Chilko Lake in central British Columbia. Arranging survival time series for both age-classes by ocean entry year and combining them, weighted by a proxy model of sampling variance, reduced the sampling variance in the original age-1 smolt survivals sufficiently to indicate a linear trend of increasing survival from 1960 to 1990 that suddenly changed at or near 1991 to a lower and declining trend from 1992 to 2008. Neither density nor mean length influenced smolt survival. Returns in a given year were not good predictors of siblings returning in subsequent years. Time spent at sea increased linearly beginning around 1970. Although smolt survivals differed between ecosystem regimes, there was only the one clear pattern break about 1991. To improve our understanding of mechanisms, survival trends were compared with environmental indices that included catches and hatchery releases of potentially competing salmon from around the North Pacific Ocean. Smolt survivals were more similar to abundance indices of Sockeye Salmon, Chum Salmon O. keta, and Pink Salmon O. gorbuscha than to indices of global, regional, or local ocean climate. Our results are consistent with the hypothesis that salmon productivity in the North Pacific declined soon after 1990. We present a simple model to illustrate how increased competition at sea, related to the release of large numbers of hatchery salmon, in conjunction with changes in ocean productivity, may have played a significant role in improving Sockeye Salmon survivals while reducing their growth before 1991. After 1991, these factors may have acted to reduce survivals while the growth of survivors showed no effect. |
author2 |
James R. Irvine |
format |
Text |
author |
James R. Irvine |
spellingShingle |
James R. Irvine Understanding Smolt Survival Trends in Sockeye Salmon |
author_facet |
James R. Irvine |
author_sort |
James R. Irvine |
title |
Understanding Smolt Survival Trends in Sockeye Salmon |
title_short |
Understanding Smolt Survival Trends in Sockeye Salmon |
title_full |
Understanding Smolt Survival Trends in Sockeye Salmon |
title_fullStr |
Understanding Smolt Survival Trends in Sockeye Salmon |
title_full_unstemmed |
Understanding Smolt Survival Trends in Sockeye Salmon |
title_sort |
understanding smolt survival trends in sockeye salmon |
publisher |
American Fisheries Society |
publishDate |
2013 |
url |
https://doi.org/10.1080/19425120.2013.831002 |
op_coverage |
world |
long_lat |
ENVELOPE(-19.455,-19.455,65.656,65.656) ENVELOPE(-130.143,-130.143,54.160,54.160) |
geographic |
Keta Pacific Sockeye |
geographic_facet |
Keta Pacific Sockeye |
genre |
Pink salmon |
genre_facet |
Pink salmon |
op_source |
https://doi.org/10.1080/19425120.2013.831002 |
op_relation |
doi:10.1080/19425120.2013.831002 |
op_rights |
All rights reserved. |
op_doi |
https://doi.org/10.1080/19425120.2013.831002 |
container_title |
Marine and Coastal Fisheries |
container_volume |
5 |
container_issue |
1 |
container_start_page |
303 |
op_container_end_page |
328 |
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1800736756301037568 |