Our rivers are far from sterile. That's another myth. I've fly fished almost every stream on the Oly Pen and others in Western Washington. They are full of caddis, mayflies, stone flies, crayfish and many more species of bugs. The upper Elwa has no migratory fish to suppliment the bug population and if you've been up there you've seen the amazing hatches and the large numbers of rainbows in the river. The upper Skokomish which is now closed and almost void of migratory fish has tremendous hatches. Remember when these rivers had thousands of smolts at the very least and maybe at one time millions they were supported by insect life in order to grow and hit the road to the ocean. I'm sure that dying fish add to the health of the insect populations but believe me there are streams that support populations of cutthroat and rainbows in Western Washington and the Oly Pen with absolutely no migratory fish to add to the health of the river. I used to believe that the rivers were too sterile to support native cutts and bows but 30 years ago when I started fly fishing it obviously led me to learn about insects and their numbers in rivers and I found that there are good healthy populations of the above mentioned bugs. There are certainly enough bugs to get a run started and as the run grows and fish die the insect populations will grow as well. But again, the rivers are far from sterile.