It has been tracked since 1992 and been labeled the loneliest whale in the world. It sings at a frequency of 51.75 Hz whereas others of it’s kind sing at 15 - 25 Hz. It does not travel along migration routes of any baleen whale species. There is no opportunity for other whales to run into it.
"The best guess of researchers is that this lonely whale is either a ‘deformed’ hybrid between 2 species of whale, or the last surviving member of an unknown species." - Impact Lab