Research project 1: Common seal capture and transmitter attachment
The hard-to-catch animals are first laboriously captured with nets at their resting sites and then fitted with transmitters and mouth sensors.
Research project 1: Attaching loggers and mouth sensors to common seals
Time-depth recorders measure and record the depth and duration of dives and the seal’s location. Scientists combine these data with feeding activity data from a mouth sensor to compile a behaviour profile for the animal.
Research project 2: Aerial survey of harbour porpoise and other marine mammals
Scientists use a twin-engined Partenavia to census marine mammals by surveying selected transects across the North Sea and Baltic Sea. The transects are just under 10 km apart in the North Sea and about 6 km apart in the Baltic Sea.
Research project 2: Aerial survey of marine mammals
The researchers record all sighted harbour porpoise and seals together with the sighting angle from the aircraft. The distance from the transect can be computed from the angle and later used to determine the area population density.
Research project 3: Porpoise click detector surveys
The German Oceanographic Museum uses stationary porpoise click detectors. The calibrated detectors are anchored to special buoys and continuously record all porpoise clicks. Every four to eight weeks, the rechargeable battery is replaced and the data copied from the device’s memory chip.
Research project 4: Use of towed hydrophones to survey harbour porpoise
In the North Sea, scientists additionally use towed hydrophones to detect porpoise. These underwater microphones pick up porpoise clicks when towed behind a vessel. Researchers are working on improvements to this detection method.