All in sight

The underlying measurement method, infrared thermography, registers both at day and night the heat radiation originating from each body. It depicts it on a computer screen as a black and white picture, thus making it visible for humans: the brighter a spot, the warmer it is. The warm spout of a whale clearly stands out against the background of the cold North Atlantic or Antarctic waters.

		IMAGE: These are two humpback whales visiting Polarstern while the ship was on station. Click here for more information.

Infrared thermography is already in use with great success, for example to examine the heat insulation of buildings. However, the ship-based detection of whales on sea presents new challenges: the camera must have "all-round visibility", it is subject to the constant movement of the ship and the spout is only briefly visible, possibly at a great distance. This poses high demands on the camera's optics: similar to animal photography, highest resolution telephoto lenses are necessary. When mounted to the ship, however, the camera would, due to the ship's motion, only point into the sky for much of the time.