I had thought this was fairly well established. But I guess these days no notion gets any respect until it's been caught on video.
But this aspect, courtesy of BBC, I did not know:
The discovery explains why thresher sharks are often caught by their tails by baited long-line fishing gear....
Fishermen often return sharks after the struggle of the catch, but because threshers tend to be caught by their tails, they have difficult breathing underwater when hooked.