A synthesis of the coast‐wide decline in survival of West Coast Chinook Salmon (Oncorhynchus tshawyt

OldBlackDog

Well-Known Member
From this study,At the broadest level, the major implication of our results is that most of the salmon conservation problem is determined in the ocean by common processes. Attempts to improve SARs by addressing region‐specific issues such as freshwater habitat degradation or salmon aquaculture in coastal zones are therefore unlikely to be successful. Given the importance of these conclusions, we call for a joint systematic review by major funding agencies to further assess the broader consistency and comparability of SAR data with our findings.


Abstract
We collated smolt‐to‐adult return rate (SAR) data for Chinook salmon from all available regions of the Pacific coast of North America to examine the large‐scale patterns of salmon survival. For consistency, our analyses primarily used coded wire tag‐based (CWT) SAR estimates. Survival collapsed over the past half century by roughly a factor of three to ca. 1% for many regions. Within the Columbia River, the SARs of Snake River populations, often singled out as exemplars of poor survival, are unexceptional and in fact higher than estimates reported from many other regions of the west coast lacking dams. Given the seemingly congruent decline in SARs to similar levels, the notion that contemporary survival is driven primarily by broader oceanic factors rather than local factors should be considered. Ambitious Columbia River rebuilding targets may be unachievable because other regions with nearly pristine freshwater conditions, such as SE Alaska and northern BC, also largely fail to reach these levels. Passive integrated transponder (PIT) tag‐based SAR estimates available for Columbia River Basin populations are generally consistent with CWT findings; however, PIT tag‐based SARs are not adjusted for harvest which compromises their intended use because harvest rates are large and variable. More attention is needed on how SARs should be quantified and how rebuilding targets are defined. We call for a systematic review by funding agencies to assess consistency and comparability of the SAR data generated and to further assess the implications of survival falling to similar levels in most regions of the west coast.






https://onlinelibrary.wiley.com/doi...SKZytUDGFvzoTy8mKHNOIdltZYsRO318y7h2HnrC0yTlE
 
Thanks for posting. Bottom line is we are back to ocean survival as a key barrier to recovery. The study pretty much points to efforts to improve habitat as a mechanism to overcome declining ocean survival is a failed strategy. The challenge is that it is not politically expedient to address the real issues. I have always believed if we addressed habitat issues, that would greatly improve recovery - tough pill to swallow, but this study is pretty conclusive.
 
Thanks for posting. Bottom line is we are back to ocean survival as a key barrier to recovery. The study pretty much points to efforts to improve habitat as a mechanism to overcome declining ocean survival is a failed strategy. The challenge is that it is not politically expedient to address the real issues. I have always believed if we addressed habitat issues, that would greatly improve recovery - tough pill to swallow, but this study is pretty conclusive.
Both freshwater habitat and fish farms seem to have minimal impact. As the article references there has never been more total salmon in the North Pacific, they're just mostly hatchery chum and pinks now.
 
Fresh water habitat has been identified as the primary population bottleneck for Puget Sound Chinook. Good study though; it is a large part of the big picture IMO.
 
Both freshwater habitat and fish farms seem to have minimal impact. As the article references there has never been more total salmon in the North Pacific, they're just mostly hatchery chum and pinks now.
This is an interesting article on Alaska salmon ranching related to bowers comment.

 
My neighbor used to commercial fish Prince William Sound & was very involved with their farming/hatchery programs. He says they chose Pinks because they were easy to raise.
 
I was on the trail beside the Chilliwack/Vedder river this fall, when a man asked me what had happened to the Salmon. He said he was a former commercial guy. I told him that it was ocean survivability, there were hundreds of dead zones and other nations ranching Salmon. Warm temps causing less nutritious plankton up north here, as that is what I knew then.
Thanks for this newer info.
 
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