I see 3 sushi restaurants on the same street, start to extrapolate in my head, and wonder how we hadn't extinguished most edible fish species decades ago.

From what I've read and heard on the subject, my understanding is: (1) some we have (touched upon at end of Jiro Dreams of Sushi, for example), (2) we are in the process of doing so to most the rest, (3) fish farms are increasingly making up the difference.