Marine mammals differ from other ocean biology as they feed in the deep oceans but breathe air from the surface. Observing and monitoring these animals can therefore be challenging. In some situations
operations are being carried out where you want to be assured that no mammals are present within a certain area. For example, where there is seismic shooting and piling. Passive acoustic techniques use
hydrophones to listen for whales, but this technique is dependent on the mammal actually vocalizing, which they do not always do.
Whale / surface interactions observed on the sonar screen. Note how the whale clicks and whistles also appear on the screen.
Omni directional sonars have proven to be very efficient in order to establish if a mammal is present or not. The Simrad omni sonars transmit both 360° horizontally and 180° vertically, enabling you
to follow the animal from the surface into the deep ocean. In the surfacing part both bubbles from the wake, the whale itself and also its vocalization can be observed on the sonar screen. All Kongsberg
Maritime sonars and echo sounders have the ability of a soft start with reduced power in early transmission to avoid transmission with mammals in the near vicinity of the transducer.