Not a lot of Ricker's science is in play in the Chehalis. The Chehalis chinook spawning goal (when it is met) only returns around 4 fish per mile of river. There is some interesting long-term data collected from many coastal OR rivers (where chinook returns are actually increasing through time) suggesting that 50 spawners per mile is a good number.

http://www.dfw.state.or.us/fish/ONFSR/docs/final/02-fall-chinook/fc-methods-coast.pdf

The Chehalis is clearly a hatchery show from a management perspective. The wild fish are just in the way.