Thanks Spring Velocity, that DFO stock assessment article pretty much outlines the Fraser River Chinook stocks and the origin of white chinook as predominantly in the Harrison...although there has been hatchery transplants in some tributary rivers, most notable being the Chilliwack. I appreciate that we may encounter whites near river mouths, but that is not evidence those rivers have runs of white chinook. That is not to say there cannot be straying from river to river; that is widely known to occur. So we shouldn't confuse that from where the river of origin is for these whites we encounter in our local fisheries.
Case in point, one of the Chinook heads that I returned from the Alberni inlet this summer was of Washington State origin...all that means is the fish likely strayed a bit following some local Somas fish into the inlet. More likely than not, that fish would have eventually wondered out of the canal and headed for home.
Notwithstanding, the crux of the original article posted was to explain how this specific genetic stain of white chinook have white flesh as opposed to the usual red flesh in most chinook families. It wasn't (as I read it) trying to position a science based reason why/how chinook from "all" rivers could develop the white flesh. These whites are from genetically specific families of chinook, and not spread widely across all river systems from my experience and read of any scientific papers on the subject.