Essentially, to me, recruitment is the spawning, stocking, replenishment and growing process of any fish or other species. Beasley can probably say it better. A 2 inch bass can be prey for big bluegills and it's a crap shoot. But, some generally survive predation, injury, etc.
Think of this. 98+% of all eggs laid never make it to spawning size fish. If you put a bunch of bass fingerlings in a grow out tank, they will eat each other.
In Texas, our problem is generally too much lmb survival and we come up with ponds that are lmb heavy and forage light. If you stock 50 you might get a dozen spawning machines or just possibly none. Due to long growing seasons, we have to start and continue culling bass after the 2nd year on new ponds.