Not knowing anything about the Dossi, the answer to your question is not an easy one. For that matter, knowing about it may not help anyway.

If there is no development or logging problems along the creek, then there must be some other problem if the creek's runs are not doing well. Probably incidental catch, but maybe the fish just aren't as hardy as others.

Hood Canal is not covered by the Puget Sound chinook listing, I think. However, Hood Canal summer chums are listed. I think they mostly return to the Quilcene, and perhaps other streams in that area. If Dossi has these chums, then it will surely be afforded some protection to protect those fish. Even if it doesn't, restrictions to protect summer chums may help, if the fish coming back to Dossi associate at all with the Quilcene chums and may be caught incidentally.
There are so many variables that play into the viability of a run, probably a lot more than we could ever quantify or imagine. Why some rivers get better returns than others is obvious if you see better habitat, but as you noted, some very developed rivers still get good returns. Who knows why? I'm sure an individualized study on those rivers, or those particular stocks, may shed some light on it.

I guess the bottom line is that any listing of a salmon or a steelhead will, to a point, afford greater protection to other anadromous fish in the same area. It sure won't hurt.

Sorry for the lame answer, but I just don't know what the status of Dossi Creek fish is.

Fish on...
Todd.