Bighorn River Browns with Fungus attached to them have been dying off.
Biologists have confirmed that it’s a normal post spawn fungus. They fight a lot during the spawn, and even more so when the flows are low and they’re crowded. The fighting leaves lots of small wounds for the fungus to take hold. Most recover, but when they are covered extensively like the fish in these photos, they usually die. Of course, by dying, they make room for bigger, healthier fish.
Atleast that’s what we would hope for.