Climate Change - Cohen Commission

Table of Contents
List of Tables. .............................................................................................................................. 11
List of Figures .............................................................................................................................. 12
List of Appendices ....................................................................................................................... 15
1. Effects of climate and climate change on survival of Fraser River sockeye salmon: a
literature review to evaluate recent trends in abundance and productivity ..................... 16
1.1. Introduction ........................................................................................................................ 16
1.2. Literature compilation ........................................................................................................ 17
1.3. Quantitative assessment of the literature ........................................................................... 18
1.3.1. General findings ......................................................................................................... 19
1.4. Effects of climate-related variables on survival of sockeye salmon .................................. 21
1.4.1. Eggs and alevins ......................................................................................................... 21
1.4.2. Fry in lakes ................................................................................................................. 22
1.4.3. Smolts and postsmolts ................................................................................................. 23
1.4.4. Immatures in the ocean ............................................................................................... 23
1.4.5. Returning adults .......................................................................................................... 24
1.4.6. Spawners ..................................................................................................................... 25
1.5. Recent climate change and sockeye salmon habitats ......................................................... 25
1.5.1. Recent trends in the freshwater environment ............................................................. 25
1.5.2. Recent trends in the marine environment ................................................................... 27
1.6. Qualitative assessment of the effects of recent climate change on Fraser River sockeye
salmon survival .................................................................................................................. 28
1.6.1. Criteria used in the qualitative assessment ................................................................ 28
1.6.2. Likelihood of trends in survival of Fraser River sockeye salmon due to climate
change over the past 20 years ..................................................................................... 29
1.7. Future impacts and potential for adaptation to climate change ......................................... 31
1.7.1. Effects of future climate change on Fraser River sockeye salmon ............................. 31
1.7.2. Adaptation of Pacific salmon to climate change ........................................................ 31
1.7.3. Adaptation strategies in the context of climate change .............................................. 32
2. Adult mortality during river migration and on spawning grounds ................................... 34
2.1. Introduction ........................................................................................................................ 34
2.2. Factors affecting survival of adult river migrating sockeye salmon: a brief review ......... 35
2.3. The Late-run Fraser River sockeye salmon issue .............................................................. 37
2.3.1. Background ................................................................................................................. 37
2.3.2. Emergence of research partnerships .......................................................................... 38
2.3.3. Causes of early migration ........................................................................................... 39
2.4. Patterns of en route mortality in Fraser River sockeye salmon ......................................... 41
2.5. Explaining trends in stock-specific en route mortality in Fraser River sockeye salmon ... 43
2.6. Relationships between migration mortality and encountered temperature in Fraser River
sockeye salmon .................................................................................................................. 44
2.7. Patterns and causes of pre-spawn mortality in Fraser River sockeye salmon ................... 46
2.8. Migration issues and potential freshwater mortality of adults in 2009 and 2010 .............. 48
2.9. Intergenerational consequences ......................................................................................... 49
2.10. Effects of en route and pre-spawn mortality on population trends .................................. 50
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