I dont know about the presence of perch meaning there are little to no bass. Bass large and small mouth eat perch, and in some places I fished back east the only thing in the water seemd to be perch and large mouth. if you find an aboundance of small-medium perch, chances are you will find Large large mouth close by. Also bass and perch compete over shallows, bass want to spawn, perch look for hunting grounds. In the bass spawn when they wont hit crays, or smelt, they will destroy anything that looks like a perch, not cause they are hungry, but becuse the perch will eat bass row.
I belive if you find alot of small fish, your gona find larger fish preying on them near by. Alot of times when I fish a stream or river I'll look for fry/minnows. When I can see them close to shore, that usualy means a predator has chased them up into the shallows. You might have landed on an eel hole?