Whales spotted from space
Counting whales has never been easy—boats, even planes, can travel limited distances, and catching site of these giant cetaceans is hit or miss. Now, researchers at the British Antarctic Survey (BAS) in Cambridge have demonstrated that they can tally at least four different species using satellite images taken 600 kilometers above the ocean.
Previously, satellite cameras were of no use in whale spotting. Their resolution, which maxed out at 46 centimeters, made most whales look like undistinguishable blobs. But the new privately owned WorldView-3 satellite, which has a resolution of 31 centimeters, enabled BAS graduate student Hannah Cubaynes to count 200 whales across 4230 square kilometers of ocean, she and her colleagues reported last week in Marine Mammal Science.
Cubaynes started with seven images from four areas across the world known to exclusively host southern right whales, fin whales, humpback whales, or gray whales at certain times of year. “Oh my God,” was her first reaction, because the whales were so easy to see. Nearly half of her identifications were definitive, and the whales looked different enough from space that she expects to be able to tell species apart should they occur together in subsequent images.
Next, researchers will use the images to develop a computer program that can pick out probable whales, the identification of which will be confirmed by experts. Cubaynes says the system will aid conservation efforts by better revealing where whales go and how many there are. But to do so, she first has to figure out how to account for wind, sun glare, and whales that are at angles to the surface or moving and thus not fully visible. And like aerial and ship surveys, satellite surveys will still be hampered by bad weather.