Scientists calculating the movement of different species of whales admit that the distances they once thought them capable of swimming may have been “drastically underestimated” and that new research suggests “they have only been looking at part of the picture.”

According to a new study, co-authored by Dr Olaf Meynecke from Griffith University and published in the scientific journal, Ecology, some species of whales are swimming as much as 20% further than previously estimated.

“For years, we have tracked whales using satellite tags, plotting their movements across oceans,” said Dr Meynecke. “But this research shows we have been looking at only part of the picture.” 

Led by a multi-disciplinary team of global researchers from the University of Connecticut, Smithsonian Institute and Pontific University of Ecuador, the study has underlined the notion that animal movement isn’t ‘confined to flat maps.’

It means that marine animals such as whales move in three dimensions – across the surface as well as up and down through the water column. It may sound like it’s stating the obvious, but it requires an appreciation of the geodesy (the science of the shape of the Earth) that previous animal tracking data simply hasn’t incorporated.

The researchers revealed that the curvature of the Earth and diving behaviour of the whales themselves, significantly extends the total distance they travel.

Using satellite data from the Whales & Climate Programme’s longest continuous humpback whale track from Ecuador to near Antarctica, the team compared two methods of measuring distance: a standard surface track of approximately 6,658km and a revised, 3D geodesic estimate that factored in average dive depths and speed.

The result was an additional 1,055km – or about 16% – more distance covered.

“For humpback whales migrating between South American breeding grounds and Antarctic feeding areas, that could mean covering up to 14,000km in a single migration season,” said Dr Meynecke. “That’s seven times more than the average human travels in a year.”

The findings have real implications for how we understand the energy demands and ecological pressures on migrating species.

“If animals are expending more energy than previously estimated, we may be underestimating the ecological costs of migration and the impacts of environmental change,” said Dr Meynecke. 

The study ‘Accounting for Earth’s curvature and elevation in animal movement modelling’ has now been published in the scientific journal, Ecology.

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