Comment by bluGill

I'm not an expert, but what I understand is Salmon return to the stream, not the place. They know the stream by smell (that is the minerals and other impurities in the water). They are navigating to what smells like home, every time a new stream enters the one they are in they decide which branch to take. This tends to take them to where they spawned, but there are a lot of errors in each choice.