Hey WA fisher I don't know what part of Alaska you are talking about but it is not perfectly pristine. Including the Keni.
There are many destructions to Alaska that you may not see as a tourist. Habitat matters every where and it does dictate the fishing. Commercial Harvest is a large cause for decline but not the only thing.
They have clear cutting going on In Alaska daily, Oil spills (Exxon Valdez) not too mention hundreds of other vessels dumping pollutants. Even drilling and and mining is still happening all over Alaska.
All these things contribute and are a major problem. The Habitat in puget sound is not perfect, when was the last time you were under water to see the habitat ?
For me it was last week. There is more crap and pollution in Elliot bay then I care to ever see. You can not point and blame it on a certain activity, it all affects it to a great deal. Look at all the 2 stroke motors out in the sound, you dont think they contribute to the depleation to the water quality? And I can tell you there are many places down south of PT Townsend where you can catch a health dose of Ling Cods. Good habitat does matter to the survival of fish along with banning nets.
Just my 02. cents...