The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.
I want to say that it's cutthroat. They on occasion will school up like that. There is one fish in particular, the one closest to the camera, seems to have spots on the tail that look as though they move up the body towards the head and then fade off like they do.
I really don't believe they are landlocked salmon.