A Microcomputer-Based Echo-Integration System for Fish Population Assessment

Abundance estimates obtained with acoustic echo-sounding equipment play an important role in the management of fish stocks. The common technique presently used is to process the signal from the echo sounder with a digital computer or to record the analog signal for later processing. A microcomputer-based echo-integration system has been developed for fish population assessment. It is a relatively inexpensive, field-oriented, portable instrument that can process data in real time from any existing echo sounder. The signal from the echo sounder is detected, digitized, squared, and averaged for various depth ranges. The averaged squared echo level is then scaled to provide a measure of the density of the fish school at the selected depth ranges. The system automatically tracks the bottom depth and prevents integration of the return from the bottom.