Fish, boat wake and rock

On this echogram there are many trails that are clearly fish. Also displayed is a boat wake (the diffuse cloud of single targets running from lower left to upper right) and a rock (the clear trail at a constant depth of ~27 m which runs across the whole echogram).

The fish, wake and rock appear at different thresholds. A polygon region with a region type of Bad data may also be used to separate the echo of fish from that of the wake.

Figure 1: This echogram displays a section of HTI data from August 2000. The data was acquired on a river and has been used for the Echoview Fish track training material with the permission of T. Mulligan.

See also

Examples of echogram interpretation