A recently published peer reviewed study of west coast Chinook salmon found that there has been a 65% decline coast-wide in the number Chinook salmon, even in some of the most pristine and untouched waters.
The study notes that Chinook return rates to the Columbia, which is 90% hatchery fish, is actually better than some totally untouched wild populations. The study points to ocean conditions and commercial over-harvest as the likely cause of decreasing Chinook populations. Kintama Research Services Ltd produced a short video (link) that explains the important findings of the study.