A lot of fish will not have CWT's, most of the one's I turned in last season did not have tags. I've seen the same in the data from Area 17, there were only 11 of 436 fish DNA sampled with CWT's. And to be fair, only 96 of the 436 fish had a clip with 11 of those having CWT, which is 11.5% with CWT tags.
On a side note I pulled some data rather than rely on my poor memory quoting 25% of the Area 17 fish coming from the Harrison/Chilliwack. So to be more precise, 146 of the 436 were Harrison/Chilliwack fish. If my math is correct those Harrison/Chilliwack fish represents 33.5% of the Area 17 catch, or did in 2014 (year I have data for)....so, in my mind this run of fish represents a fairly significant contribution to the local fishery. This being a down year for these rivers according to the forecast could mean little less robust fishing than last year.
Hope that helps frame it better.