Swimming in Circles - Sonar Imaging Example
Two salmon swimming in circles illustrates the effect of aspect angle (the angle of the fish with respect to the sonar) versus target strength (visibility/brightness). A side aspect has a much higher target strength than a head (bad) or tail (worse) aspect, as evidenced by the fish image which practically disappears and reappears as the fish swim through the circle. Deel River, Ireland.
Courtesy of Louise Brennan, Marine Institute, Furnace, Newport, County Mayo, Ireland