One of the aims of our project was to try to understand how the whales may change their feeding behaviour depending on the behaviour of their prey: the herring. This might seem like an easy enough task, but think again...the waters where we find the whales have very low visibility. Try putting an underwater camera in the water and within a few seconds, as the whale moved just a few metres, you can't see anything but the blue. So, observing the feeding behaviour of a whole group of whales like that is just impossible!
Luckily we can rely on a cool piece of kit: a multibeam sonar. The sonar scans the water and provides us with a picture of what is going on. Because it emits pulses of very high frequency it provides a higher resolution image than a traditional echosounder and its this image that we can use to see how the whales behave when feeding on herring. It also has a very wide horizontal beam and gives us an image up to about 100 m distance. Suddenly a whole new underwater world is visible.
The support of Teledyne RESON has made it possible for us to use one of their sonars and some of the images we have obtained can now be seen here. We will be using the sonar again in 2014 so hopefully we can continue exploring the underwater world of feeding killer whales.
