The July/Aug edition of Reader’s Digest has an article, America the Tasty, about different favorite foods in each state.
For Idaho they picked fried trout. But went on to make that claim - " along one stretch of the Snake River, there are 6,000 wild rainbow trout per mile". Wow, that would work out to just over 11 trout every 10 ft, (~ 3m). Not sure if I believe the claim, unless it is a very difficult place to get to with not much fishing pressure. If true, clearly an indication of a healthy habitat.
Oddly a few days ago I went fishing on the Greenbrier River, and caught a 15 in rainbow trout after about five cast. Not all that unusual in spring time or late fall. But usually all the trout disappear from the larger stream by late June as the water becomes to warm, and what trout remain are either caught, die or retreat into the smaller more shaded streams that are also closer to cooler water discharging from springs. The rest of the fish caught were fallfish, small mouth bass, redeye, the occasional bluegill, and a few I was not sure what they were. They all seemed to like a cahill body, #8 hook kebari.