A humpback whale is seen breaching outside of Sydney Heads. Cameron Spencer/Getty Images

Humpback whales seen in Australia each year as they swim along the eastern and western coasts are so different to their cousins in other parts of the world that the could be a sub-species.

An international group of scientists has established that humpback whales from different parts of the globe are more genetically distinct than previously thought.

The researchers, using the most comprehensive genetic dataset on humpback whales so far, determined that humpback mostly stick to their own oceans have have little to do with others in other seas.

Humpback whales in the ocean basins of the North Pacific, North Atlantic and Southern Hemisphere are much more isolated from each other than previously thought.

This is despite the fact that their seasonal migrations between winter breeding grounds and summer feeding grounds are longer than for any other mammal.

Dr Jennifer Jackson of the British Antarctic Survey says there’s evidence oceanic populations should be recognised as separate subspecies, isolated by warm equatorial waters, which they rarely cross.

Genetic evidence suggests that hump-backs in the North Pacific, North Atlantic and Southern Hemisphere are on independent evolutionary trajectories.

The paper, Global diversity and oceanic divergence of humpback whales (Megaptera novaeangliae), is published in the Proceedings of the Royal Society B.

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