From the logs of The Whalesong Project, located in Kihei on Maui:
I think this is not a haka, but a powhiri, if I’m not mistaken. Hakas are war chants, and this sounds like a powhiri, the kind of song sung on the marae to welcome vistors. Please correct me if I’m wrong. The song is haunting, and especially the way the humpback seems to respond. While I was in Maui last month, we went whalewatching and saw 20 humpbacks and sat transfixed listening to them sing as well. You can find more about Maori whale songs at folksong.org.nz
By the way, the Parking Lot soundtrack, a list of all the mp3’s I have been collecting here over the past year is hosted at Webjay. You can go visit and stream the whole thing. It’s a pretty good listen, if I do say so myself.