" I don't know what the carrying capacity of the Chehalis Basin is "

Well nobody does as it has not been properly defined other than miles of stream = X. But in its natural state the Chehalis was a Coho producing machine and if I recall when we did that exercise a very low run was around 180K and this was not necessarily pre European but rather pre cannery. In fact the biomass of the carcasses was so large that if you took every carcass from returns from every hatchery in the state and put it in the Chehalis Basin you were still short of the natural biomass pre settler.

The thing is prior to canneries the tribal fisheries supplied salmon for the town inhabitants or another way to say it is they were the commercial fisheries. The massive change came when cannery technology was developed and $$$ were to be made, big time.