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Assessing the Relative Importance of Local and Regional Processes on the Survival of a Threatened Salmon Population

ScholarsArchive at Oregon State University

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Title Assessing the Relative Importance of Local and Regional Processes on the Survival of a Threatened Salmon Population
Names Miller, Jessica A. (creator)
Teel, David J. (creator)
Peterson, William T. (creator)
Baptista, Antonio M. (creator)
Date Issued 2014-06-12 (iso8601)
Note To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by the Public Library of Science. The published article can be found at: http://www.plosone.org/.
Abstract Research on regulatory mechanisms in biological populations often focuses on environmental covariates. An integrated
approach that combines environmental indices with organismal-level information can provide additional insight on
regulatory mechanisms. Survival of spring/summer Snake River Chinook salmon (Oncorhynchus tshawytscha) is consistently
low whereas some adjacent populations with similar life histories experience greater survival. It is not known if populations
with differential survival respond similarly during early marine residence, a critical period in the life history. Ocean
collections, genetic stock identification, and otolith analyses were combined to evaluate the growth-mortality and match-mismatch
hypotheses during early marine residence of spring/summer Snake River Chinook salmon. Interannual variation in
juvenile attributes, including size at marine entry and marine growth rate, was compared with estimates of survival and
physical and biological metrics. Multiple linear regression and multi-model inference were used to evaluate the relative
importance of biological and physical metrics in explaining interannual variation in survival. There was relatively weak
support for the match-mismatch hypothesis and stronger evidence for the growth-mortality hypothesis. Marine growth and
size at capture were strongly, positively related to survival, a finding similar to spring Chinook salmon from the Mid-Upper
Columbia River. In hindcast models, basin-scale indices (Pacific Decadal Oscillation (PDO) and the North Pacific Gyre
Oscillation (NPGO)) and biological indices (juvenile salmon catch-per-unit-effort (CPUE) and a copepod community index
(CCI)) accounted for substantial and similar portions of variation in survival for juvenile emigration years 1998–2008 (R² > 0.70). However, in forecast models for emigration years 2009–2011, there was an increasing discrepancy between
predictions based on the PDO (50–448% of observed value) compared with those based on the NPGO (68–212%) or
biological indices (CPUE and CCI: 83–172%). Overall, the PDO index was remarkably informative in earlier years but other
basin-scale and biological indices provided more accurate indications of survival in recent years.
Genre Article
Access Condition http://creativecommons.org/licenses/by/3.0/us/
Identifier Miller JA, Teel DJ, Peterson WT, Baptista AM (2014) Assessing the Relative Importance of Local and Regional Processes on the Survival of a Threatened Salmon Population. PLoS ONE 9(6): e99814. doi:10.1371/journal.pone.0099814

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