After witnessing one of these events himself back in 2009, Robert Pitman was compelled to investigate further. He began collecting accounts of humpback whales interacting with orcas, and found nothing short of 115 documented interactions, reported by 54 different observers between 1951 and 2012. The details of this surprising survey can be
found in the journal Marine Mammal Science.
In 89 percent of the recorded incidents, the humpbacks seemed to intervene only as the killer whales began their hunt, or when they were already engaged in a hunt. It seems clear from the data that the humpback whales are choosing to interact with the orcas specifically to interrupt their hunts. Among the animals that have been observed being rescued by humpback whales were California sea lions, ocean sunfish, harbor seals, and gray whales.