Here's some good reporting by Montana Standard reporter Michael Cast on the decline of trout numbers, especially brown trout, on rivers in the southwest part of the state.
There's bad news on the Big Hole, Ruby and Upper Clark Fork rivers. The numbers on the Madison and Yellowstone are also declining. Biologists don't yet have a good idea what is driving the population trends, since the numbers have been poor even in good water years.
FWP is considering changes to fishing regulations on the Big Hole River in the popular lower river near Melrose, where brown trout have declined from 1,800 to 400 in the last six years.