Stlhdh2o -
My understand is that the pacific trout (cutthroat and rainbows) and salmon evolute from a common ancestor(s). The early "trout" was a freshwater fish that gave rise to first the trout and later developed into the various salmon species. So on the evolution ladder rainbow and cutthroat are more primitive than salmon with coho next, sockeye, chinook, chum and finally pinks. Not sure where the asian cherry salmon fits. Notice the each "newer" species spends less of its life history in freshwater. There is extensive articles about this and suggest if you want more information check some of the work by Dr. Benke (spelling?).

Are there Western Washington streams with healthy resident trout? Cutthroat or rainbow? Above or below anadromous barriers? The forks of the Snoqualmie above the falls has both rainbow and cuthroat, upper South Fork Skykomish has both, South Fork Tolt (anadromous) has rainbows (closed to fishing), Upper North Fork Tolt rainbows (CnR). Many of the larger tribs on the Skagit/Sauk as well as O.P. streams (above and below barriers), especially within the park have rainbows. Within a little poking around some surprising good trout fishing can be found, just have to put aside the big rods. By the way if do start poking around on some of the anadromous portions of these streams don't be surprised if you met a summer-run or two.

Assistant baiter -
Dolly Varden and bull trout, as well as artic char are closely related species that can still hybridize with each other. The current thinking is that they (like the trout and salmon) developed from a common ancestor. In the last age(s) the thinking that were at least three general refugia from the ice cover; one in the Bering/Artic area, one in the Queen Charlette Island area, and one in the Western Montana. The char were isolate in these refugai and diverged from each other over the 10,000s of years with the Artic char developing in the North, the Dolly Varden in the middle and the bull trout in the interior. After the ice receded the fish spread out with the bull trout and Dolly Varden coming into contact in Western Washington and British Columbia. The Dolly Varden and artic char coming into contact with ech other in Alaska (Bristol Bay area?). The above is very much simplied but should give you some background info.

Tight lines
Smalma