Suppose I'm a singer-songwriter in the United States, and at one of my concerts, I perform a previously unreleased (and in fact never-before-recorded) song. I play this song from memory and by ear; I have never written down the tune or words. Perhaps I invented this song while on tour, and I intend to make a recording when my tour is over. Over the course of the tour, there are thousands of eyewitness accounts to this song's existence and its authorship by me.
Before I ever produce a recording of the song, though, a fan produces some kind of derivative recording (a cover, or a song that's simply very similar) of my song. Do I have any grounds to claim copyright infringement, considering that I never fixed the work as either a sound recording or written musical composition? (Let us ignore the fact that I could lie by creating such a fixation after the fact and saying that it predates the recording -- suppose I honestly admit as a point of pride, or am unable to deny due to long-term witness accounts, etc., that the song was never fixed prior to the creation of the fan work.)
What if a fan recorded my actual performance with a camera at my show? In that case, I was in no way responsible for the creation of the recording, but a significant part of the recording's value is my music. Do I have a copyright claim to control the distribution of such a fan recording, and does the prior existence of such a recorded fixation influence the derivative-work case above?