No problem. The fish “on gravel” are spawning or trying to. Hens dig the redds, bucks sniff around behind and jockey to spawn. They typically don’t bite or take lures while actively spawning, though I’ve seen some pretty aggressive hits from angry males, especially when other fish are present. However, It can frustrating to make a thousand good drifts by fish you can see, only to be ignored, or foul hooking a fish.
The typical bottom bouncing rig you use in the rivers is essentially a Lindy rig. cast quartering up stream. Use Some kind of weight(just enough to tick bottom)on your mainline or dangling from a dropper, either fixed or sliding, to a swivel and a leader (8-12lbs test) from 12” to 3-4’on up to your offering, a fly, some spawn, etc. it seems the longer the leader the more apt you are to floss, line, or foul hook a stationary fish. But try no to get carried away only fishing to fish you can see on gravel. But you have to start somewhere, and if those are the only fish around…. Many times, the holes behind gravel runs can be stacked with fish you can’t see. Those fight much better, and if out for a meal, they have slightly better meat. Plus there’s a good chance of hooking a nice trout or steelhead that’s eating eggs and bugs getting kicked up by the salmon on the gravel. Hope this helps a bit. Good luck!