There's been talk of the need for a cooperative west coast effort. I followed the story up here, north. Some said predation by mackerel, new migration predation (giant squid are showing up near Vancouver), foreign-owned fish farms (Norway) and parasites, different salmon migration patterns, overfishing.
Here's a couple of articles:
http://www.straight.com/article-2476...r-river-salmon
http://www.theglobeandmail.com/news/...rticle1249976/
Atlantic salmon are showing up in Paris France (the Seine) - first time in almost a century
http://news.bbc.co.uk/2/hi/europe/8196801.stm