Even knee deep in the surf, with ultralight rod and reel in hand, you'll latch on to fish that will fight you. Especially if the rod is in the hands of a six year old. All the artificials you usually use in the salt will work, just think small. Another way to fish small is to fish the rocks. Rock groins along the coast, jetties, or bayside rock structures all hold fish.
Food hangs out there.
You can use the same strategies that you used in the surf, or you can actually fish between the rocks. These are very thin wire hooks about an inch long with a quarter of an inch gap. That's right, quarter of an inch. You could catch home aquarium fish on these hook if you wanted to. If you can't find these hooks, use the smallest ones you can find.