On another thread Smalma indicated that the small number of resident trout I have observed while fishing Western Washington rivers may be due to the predominant use of bait as a lure (I hope I am paraphrasing somewhat accurately).

I had always been under the impression that the small numbers were due to being outcompeted for food by anadromous species. I have been passing this idea on to fishermen with less experience than myself. Is this a completely baseless idea?

Have there been any studies showing a systematic decline in resident trout populations in Western Washington rivers? If so, has a correlation with bait usage ever been documented? What about the idea of competition with anadromous fish not so much for spawning area but for food? I guess now that I think about it you could look at the anadromous fry as a food source...

Sorry if I am going over ground that has already been covered...