Standard and Multi-Frequency Echo Sounders, also called Multi-Beam SONAR, allow scientists to estimate the size of plankton and fish populations. Echo sounders may also be used for species identification. This acoustic technology increases the success of imaging animals underwater as fish species respond differently to different sound frequencies, and produce different acoustic signals. This means that this technology is especially well-suited to tracking the movements of marine animals under a research vessel.
The towed body housing the Echo Sounder used for the observation of fish and plankton, even at great depths. (Mid-Atlantic Ridge Ecosystems - MAR-ECO)
A diagram demonstrating the greatly increased coverage effectiveness of Multi Beam (right) versus Single Beam (left) Echo Sounding. (NOAA Ocean Explorer)
A depiction of SONAR Multibeam Scanning along the surface of the seafloor. (Dive Discover, Wood's Hole Oceanographic Institute)
Actual output data of animal movements in the water column; collected using an echo sounder. (Technology Working Group)