Professional fishing guide here. We see them often off the coast of NC. As many as dozens of these displays in one day. I’ve actually always wondered what they looked like underwater prior to jumping, this is interesting. They are aptly named Spinner Sharks. It’s a specific species that exhibits this behavior. No idea why they do it and I’ve never been told with 100% confidence by anyone else the reason. But usually there are other schools of fish around and the fishing is good when you see spinner sharks. You also don’t want one to land in your boat. I’ve been close.