They trapped more than they hunted and fished. Traps keep working while you sleep or do other things. Fish traps are fairly easy to make with primitive materials. So are traps and snares for small game, but even alligator and bear traps can be made with primitive tools. I've studied some of these techniques and have taught them to Scouts for survival training. I once watched a demonstration by Seminole Indians of how they build an alligator trap. They start in waist-deep water driving posts into the earth, closely spaced and webbed together with vines. They make a V-shape about 10-feet wide and narrowing as it shallows into a narrow column about one gator wide and one and a half gators long with the bait at the end of it. The trick is that the gator is swimming when he enters the trap, but walking on dry land by the time he gets to the bait. And there he waits until the Seminoles come to get him. They have learned by observation that a gator can't walk backwards because of his tail. If he can't turn around or swim out, he's trapped. Very clever, I thought.
