Migration Mystery

He traveled thousands of miles, circumventing half a continent in the course of a remarkable journey. The leviathan took off from the sheltered waters of Madagascar’s Antongil Bay, breaching, lob-tailing, flipper-slapping his way south along the east coast of Africa. It was the start of a regular migration route that this population of humpback whales follows at the end of each winter season to their summer feeding grounds in nutrient-rich polar waters. After the summer feast, most whales make the return journey, looping back to the Indian Ocean’s tropical waters where they breed and calve.

But two winters later, the humpback that had been sighted swimming with its mother in Antongil Bay in 2000 by researchers from the Cetacean Conservation and Research Program (CCRP)—a joint program between the Wildlife Conservation Society (WCS) and American Museum of Natural History, led by Dr. Howard Rosenbaum—had not returned with its group. Instead, the whale surfaced in the Atlantic Ocean off the coast of Loango National Park in Gabon—on the opposite side of Africa. The journey of this intrepid inter-oceanic traveler was the first of its kind ever to be tracked in a genetic study.

The CCRP researchers discovered the pioneer in an examination of DNA samples extracted from skin biopsies collected from whales in the wintering grounds of both the Indian and South Atlantic Oceans. WCS scientist Dr. Cristina Pomilla, the study’s lead author, and Rosenbaum suspect that the whale could have been a three- to four-year-old juvenile at the time of the second encounter with researchers.

Though Pomilla states that the movement of whales from one ocean to another has always been possible, it is very difficult to track; the only other documentation of such a migration dates back to when the species still was hunted commercially, before receiving protection from the International Whaling Commission in 1966. Two whales that were marked off western Australia, in the Indian Ocean basin, were later killed off the coast of eastern Australian, in the Pacific Ocean.

The identification of individual whales moving between ocean basins will help inform a number of conservation activities relating to humpback whales, including how these populations are defined, studied, and managed. "These findings will help us improve our understanding of how populations of whales are connected, both genetically and even culturally, in the form of the haunting songs that this species is well-known for," said Rosenbaum.

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