By Eve Savory, CBCNews.ca

With all the reports about warming seas and a diminishing food web, you'd think there wouldn't be much for the ocean’s creatures to cheer about.

But you wouldn’t know it from the song a humpback whale sang a few days ago in Blackfish Sound, off the northeast coast of Vancouver Island.

Dr. Paul Spong, who founded Orcalab on Hanson Island in 1970 to study the resident orcas, caught it on tape. He calls it a "true song" of the humpback whale.

"We were mesmerized," he says.

The song is especially important to Spong. Without his work, and that of his Greenpeace colleagues, it might never have been heard.

By the 1960s, whales were being slaughtered in such large numbers that the humpbacks were on the edge of extinction. That’s when Spong – one of the Greenpeace founders - took off for the high seas, where he and others buzzed whaling ships and put themselves between the harpoons and the whales. In 1966, the International Whaling Commission put a moratorium on whaling. (Japan continues to whale and intends to kill 50 humpbacks a year in Antarctica - starting next month.)

It was almost too late for those humpbacks that made their home between Vancouver Island and the British Columbia mainland. By 1967 they had all been killed. But 25 years ago, one humpback was spotted, then another, and now there could be as many as 77 hanging out in the area.

Now, says Spong, it seems "they are bursting into song" - a half-hour "Humpback Rhapsody."

To this human’s ear, the whale – Spong thinks it’s a male - sounds in turn tentative, querulous, bold, and questioning, interspersed with the occasional "Yippee!"

Working out his courting lines, perhaps ….