Could our unbridled factory hatchery program be part of the problem?
Alaska releases close to 2 Billion artificially produced  hatchery  salmon.  Russia another 2 billion, Japan another two billion.  Over 6 Billion introduced excess introduced mouths to feed in North Pacific  ecosystem.  
The Proceedings of the National Academy of sciences has a theory this is unwittingly causing disruptions in our marine birds. 
Climate change, pink salmon, and the nexus between bottom-up and top-down forcing in the subarcticPacific Ocean and Bering Sea 
http://www.pnas.org/content/111/18/E1880.full.pdf
We need to begin to pay attention to this... not ignore these excess mouths to feed in a changing climate