Thanks for that. Have you by any chance read the 'Great bear of Almanac'? There was essentially an account where a polar bear leap on a bowhead whale trying to kill it. The bear failed of course.
Garry Brown in his book Great Bear Almanac (1993) is citing a story from the 1991 book No Room for Bears by Frank Dufresne. The following is the original Dufresne's account:
Nanook fight anything when hungry," declared Pooshuk, and grinned as another example came to mind. Once while hunting bowhead whales in the crumbling June ice with brass harpoon gun, he and his oomiak crew members had seen a polar bear jump on the back of a surfacing whale, go down with it, and come up again still trying to bite a mouthful of blubber off the forty-ton behemoth.
Because they had no choice but to hold their compass course, Jim and his seven Eskimos plodded steadily toward the things barring their way to Point Barrow until they'd narrowed the distance enough to make positive identification. "The dark object was not a seal," stated Trader Jim. "It was the carcass of a huge bowhead whale foundered a quarter mile off the beach line. The white creatures were bears. We counted more than a hundred of them tearing chunks of blubber off the whale. Some were lying around on the ice sleeping off their blubber jags; some were walking along the whale's back; some others had eaten a hole into the belly of the whale big enough so they were walking inside and coming out the whale's mouth." Jim shook his head as if to clarify the scene. "It was the damndest sight you ever saw!"