There is some pretty good info on the Elwha estuary and access to it on this website.
SF

http://www.coastalwatershedinstitute.org/events.htm

It's not quite that simple. I get your point, but the quality of the habitat also dictates the quality of the smolts leaving that river. If the quality of the habitat is really good, the number of smolts will be high, but so will their relative size and health. Large, healthy smolts have a much higher chance of achieving adulthood, and returning to spawn than smaller, malnourished smolts.

So really good habitat produces both larger quantity AND higher quality of smolts.

There is lots of data to show that when the FW habitat is of higher quality (more nutrients, more complexity for niches, more flow, etc) that you get more adults back.

In one pristine AK stream, simply increasing the pink escapement increased the coho harvest (they fish the run at 60%) from 1,000 to 8,000 fish.

Not to denigrate the importance of the ocean, but FW is very important too.

The original moratorium: “closed to recreational, commercial and subsistence fishing”
Latest announcement “closed to recreational and commercial fishing”

Of course it's not as simple as any one factor, but it sounds to me like we agree on my main point, assuming what we are implying is that fish, themselves, are critical freshwater habitat.

I stand by my (low-risk) assertion that whatever the smolt production might be, escapements won't end up significantly better in the Elwha relative to, say, rivers like the Hoh and Queets. If the Elwha were in Alaska, it might get back more adults from its improved habitat, but it's baked into ocean fishery plans to never allow such horrors as what happened in your account of the AK stream in your post above to happen in the Lower 48.

That's true. We must prevent catastrophic over escapement at all cost. Overescapement being one fish over, catastrophic being two. Better to be under so we're sure that problems aren't created.

I am not sure that the Elwha, especially above the canyon, can be well seeded unless the ocean is severely curtailed because you need to bog old fish and the old big fish.