I would add that certainly one of the most comprehensive studies was the Cohen commission report back in 2012. Justice Cohen did conclude that there was really no smoking gun, no single stressor, responsible for declining stocks. He said multiple factors are contributing to that: climate change, non-sustainable logging practices, urban development, industrial pollution, overfishing and a variety of other factors. This is obviously an incredibly complex situation.
As Mr. Young described, you're talking about a very challenging environment through which the salmon have to migrate in order to reproduce.