Whales from Space: Counting Southern Right Whales by Satellite

Scientists have demonstrated a new method for counting Southern Right whales from space.

It uses very high-resolution satellite pictures and image-processing software to automatically detect the great mammals at or near the ocean surface.

A test count, reported in the journal Plos One, was conducted on southern right whales in the Golfo Nuevo on the coast of Argentina.

The automated system found about 90% of creatures pinpointed in a manual search of the imagery.

This is a huge improvement on previous attempts at space-borne assessment, and could now revolutionise the way whale populations are estimated.

Currently, such work is done through counts conducted from a shore position, from the deck of a ship or from a plane but these are necessarily narrow in scope.

An automated satellite search could cover a much larger area of ocean and at a fraction of the cost.

Peter Fretwell

"Our study is a proof of principle," said Peter Fretwell from the British Antarctic Survey.

"But as the resolution of the satellites increases and our image analysis improves, we should be able to monitor many more species and in other types of location.

"It should be possible to do total population counts and in the future track the trajectory of those populations," he told reporters.

The breakthrough is in part down to the capability of the latest hi-res satellites.

In this study, Mr Fretwell and colleagues used DigitalGlobe's WorldView-2 platform.

This is among the most powerful commercial Earth observation platforms in operation today, and can see surface features down to 50cm in size in its panchromatic mode (black and white).

The team selected as their test area a 113-sq-km segment of the Golfo Nuevo on the Peninsula Valdes, a location famed for its gatherings of calving southern right whales.

Even though these are large animals, they still only take up a few pixels in the satellite picture.

Nonetheless, a manual search of the scene found 55 probable whales, 23 possible whales and 13 sub-surface features.

More Information: 'Whales from Space: Counting Southern Right Whales by Satellite' Peter T. Fretwell, Iain J. Staniland, Jaume Forcada - Plos One: Published: February 12, 2014 DOI: 10.1371/journal.pone.0088655