Most of the fishing I’ve seen in Yellowstone is fly fishing. But I’m not a fisherman so what do I know. I do know kids under 16 don’t need a permit and an adult does, but the fees are cheap. And there's no state license needed. But the regs can be complex, some regulate the bait used, and some are catch and return and so on. Plus there are regs about what’s open and when. I think it would be very useful to go on the Yellowstone link about fishing in the park and see what they say. But I’m sure some real fishermen on the forum can give you some good tips, like the best places to fish, etc.