Looks like a bass bed kind of. The fish will clear out an area free of silt in the gravel to lay their eggs in several fish may be using the same redd. Don't ask me where they got the name. I will fish bass off beds but you very seldom see anyone fishing trout on them. Even crossing the river upstream of them can kick up enough silt to suffocate the eggs. I target transition areas were the fish stack up moving to and from so as not to target active fish. As hard as trout pull it's amazing just a little over handling they are belly up if you don't revive them very good. That I why I have my lights and camera set up immediately next to me on the bank with the camera on remote control I can land lift take a pic and let them go in harmed.
It surprises me that they even allow fishing there this time of year.. The locals are very protective of their browns... Even though your allowed to don't keep a brown to eat.. I learned that real fast when I watched some kids do it.. they were getting some serious looks.. no reason to anyway with the insane amount of tasty rainbows in there.. I use to make the trip every year.. miss that place.