New technology provides automatic whale detection system for ships

20/07/2009 08:58:50 The Alfred Wegener Institute tests infrared system for the protection of whales

July 2009. A new measurement system for the detection of whales is being used for the first time on board of the research vessel Polarstern. Whales are usually very difficult to spot: On the one hand, they spend the greater part of their life under water, while on the other, only a small part of their body can be seen when they do surface.

Visual sightings by marine mammal observers are therefore usually based on observations of the spout. It rises to a height, depending on the whale species and wind conditions, to between one and ten metres above the sea and remains visible for at most only a few seconds. A thermal imaging camera has been specifically designed to detect the heat of this spout, and will be deployed for the first time on the current expedition of RV Polarstern.

Day and night
The underlying measurement method, infrared thermography, works during the day and at night as it detects the heat radiating from each spout. It depicts a spout on a computer screen as a black and white picture: 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.

Ship-based detection of whales at sea presents new challenges for this technology: 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 wildlife photography, high 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.

New technology produces vast amounts of data
A new thermal imager developed by Rheinmetall Defence Electronics, Bremen, Germany overcomes these challenges. The system, called FIRST Navy, was installed during Polarstern's last port call on a highly stabilized platform in the ship's crow's nest at a height of about 28 metres. The system generates five thermographic all-round images per second with a resolution of 7200 x 563 pixels of about 4 megapixels each. The stabilization compensates the ship's movements with the effect that the upper edge of the image is always aligned with the horizon and the surrounding water surface does not move out of the picture. The system produces about a terabyte of data each day.

Researchers from the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association currently develop software to evaluate this data volume automatically. ‘We are very happy that the hardware of the system works successfully on board of Polarstern. The software is designed to search the stream of pictures for whale spout', explains Dr. Olaf Boebel, head of the research group Oceanic Acoustics at the Alfred Wegener Institute. He is in charge of the research project MAPS (Marine Mammal Perimeter Surveillance).

The aim is to transmit the direction and distance of a whale sighting to the ship's command in real-time. Ships equipped with such a system can, for the protection of the whales, respond by taking evasive action or by suspending seismic activity. Furthermore, the system can directly support research projects concerning whale populations in the scarcely researched Antarctic regions. Further application possibilities may be possible for ship safety, such as evasion of icebergs.

The MAPS project is run at the Alfred Wegener Institute by the research group Oceanic Acoustics in collaboration with the department of logistics, the shipping company F. Laeisz (Bremerhaven) and Lloyd-Werft Bremerhaven. It is funded by the German Federal Ministry of Education and Research and also through the Federal Environment Agency by the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety.