The thing I find fascinating about fish genetics is how rapidly they change in reaction to environmental and harvest changes. Take Coho if you have a stream impacted by hatchery straying and other human activities and you stop human influence it takes only about three generations ( nine years ) for the genetic traits that environmental conditions dictate for Coho ( or salmon in general ) to evolve or be on their way so to speak. Steelhead have so many different variables in their life cycle from one place to another that it a rather difficult to point to any one thing being the damaging influence. That is the rub here as the answer is all the above which immediately crosses into a huge number of social and economic things that will likely doom many populations. You see it is easy to be and environmentalist when another carries the burden and the areas are rural. When it begins to to restrain or impede urban activities then then Steelhead rapidly become far less important to a vast majority of folks especially our elected officials.