Humpback whales on different sides of the southern Indian Ocean are singing different songs, according to a new study conducted by American and Australian researchers. The report challenges the past assumption that whales in the same ocean basin sing songs with similar themes.
The humpback songs were recorded during the 2006 breeding season along the coasts of western Australia and Madagascar. The analysis was published in the January edition of the journal Marine Mammal Science.
“Songs from Madagascar and western Australia only shared one similar theme; the rest of the themes were completely different,” said lead author Anita Murray, who is pursuing her doctorate at the University of Queensland in Australia. “The reason for this anomaly remains a mystery. It could be the influence of singing whales from other ocean basins, such as the South Pacific or Atlantic, indicating an exchange of individuals between oceans which is unique to the Southern Hemisphere.”
The findings could provide new insight into how whale culture spreads. Male humpback whales are generally the ones that sing. The songs include rising and falling wails, moans and shrieks that repeat in cycles lasting up to half an hour.
Researchers suspect that individuals from different humpback populations could transmit songs to one another when they are share feeding grounds or cross paths during migration.
Salvatore Cerchio, a conservationist with the Wildlife Conservation Society and one of the paper’s co-authors, said scientists will have to survey songs beyond a single breeding season. “Continued monitoring of these songs can provide us with valuable information on how whale songs are exchanged and how those channels of cultural transmission can be protected in the future,” Cerchio said.