There were WAY more fish in the lower river due to a couple reasons.

One of the important things to know about the Dean is that there is a canyon just 4 miles from the salt. This canyon is probably nothing like a typical canyon that "our" salmon and steelhead pass through. It is literally a non-stop pile of tumbling foam. Looking at it, it is almost impossible to imagine ANY fish getting through it. Once the fish do get through the canyon, they tend to rest up in the next couple of miles. Many people, in fact, do nothing other than spend their entire trip on the lowest part of the "above the canyon" water. I view that as rather boring but if all you want to do is catch fish, socialize with your group (and nearby groups), and you don't mind fishing the same water over and over then it isn't a bad plan.

With the high water this year, apparently, many of the fish couldn't/wouldn't go through the canyon until the flows actually went down. I think that we saw more fish in the lower river for this reason. The other factor is that the water was so high when we were up high that the fish that WERE there, were more difficult to target. I suspect that had we showed up a few days later, we would have found far more fish up river.