DESCRIZIONE
This disclosure provides an underwater detection apparatus (1) for detecting a target object by acquiring underwater echo signals at fixed timing intervals. The apparatus includes an operation area specification module (80) for specifying an area (for example a user input interface module to enter the information from a fisherman) used for the calculation of target-specific discriminating information of the target object, an operation area setting module (44) for establishing an application area for calculating the discriminating information based on the presence or absence of a depth information at each fixed timing interval and on the depth information being or not between the shallowest depth and deepest depth of the specified area, and a target discriminating information calculation module (40) for calculating the discriminating information based on the echo signals within the application area.