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<p>Aquatic ectotherms are hypothesized to be vulnerable to warming and deoxygenation associated with environmental change because temperature and oxygen (O<sub>2</sub>) supply can restrict aerobic scope (AS) in captivity. However, evidence of a direct association between AS and fitness in the wild is lacking, inspiring debate about the circumstances under which AS is the primary driver of population fluctuations. Using respirometry data, telemetry studies, long-term population monitoring, and in situ predator-prey experiments, we related AS to two Chinook salmon (<i>Oncorhynchus tshawytscha</i>) population bottlenecks in the wild, juvenile rearing and migration. We found that AS, which we quantified using the metabolic index (ɸ), was associated with success probability for these bottlenecks only under a relatively narrow window of viable environmental conditions, depending on intraspecific metabolic trait diversity and hydrologic conditions. Opportunities for potentially high-impact temperature- and O<sub>2</sub>-specific conservation and management actions using existing hydraulic engineering infrastructure could therefore exist when AS is between critical (ɸ<sub>crit</sub>) and stable (ɸ<sub>stable</sub>) values. Outside of this ecological threshold, changes in AS did not yield appreciable fitness benefits because successful rearing and migration were either exceptionally improbable (i.e., AS&lt;ɸ<sub>crit</sub>), or seemingly independent of AS (i.e., AS&gt;ɸ<sub>stable</sub>). In addition, AS impairments likely increased susceptibility to predation, and this may have been involved in the putative association between AS and fitness in the wild.</p>

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Linking aerobic scope to fitness in the wild reveals potential opportunities to help recover imperiled salmon populations

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年2月4日

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  • Benjamin P. Burford,
  • Brendan M. Lehman,
  • Kenneth W. Zillig,
  • Vanessa K. Lo,
  • Alexandra G. McInturf,
  • Garfield T. Kwan,
  • Dennis E. Cocherell,
  • Nann A. Fangue,
  • Cyril J. Michel

摘要

Aquatic ectotherms are hypothesized to be vulnerable to warming and deoxygenation associated with environmental change because temperature and oxygen (O2) supply can restrict aerobic scope (AS) in captivity. However, evidence of a direct association between AS and fitness in the wild is lacking, inspiring debate about the circumstances under which AS is the primary driver of population fluctuations. Using respirometry data, telemetry studies, long-term population monitoring, and in situ predator-prey experiments, we related AS to two Chinook salmon (Oncorhynchus tshawytscha) population bottlenecks in the wild, juvenile rearing and migration. We found that AS, which we quantified using the metabolic index (ɸ), was associated with success probability for these bottlenecks only under a relatively narrow window of viable environmental conditions, depending on intraspecific metabolic trait diversity and hydrologic conditions. Opportunities for potentially high-impact temperature- and O2-specific conservation and management actions using existing hydraulic engineering infrastructure could therefore exist when AS is between critical (ɸcrit) and stable (ɸstable) values. Outside of this ecological threshold, changes in AS did not yield appreciable fitness benefits because successful rearing and migration were either exceptionally improbable (i.e., AS<ɸcrit), or seemingly independent of AS (i.e., AS>ɸstable). In addition, AS impairments likely increased susceptibility to predation, and this may have been involved in the putative association between AS and fitness in the wild.