Detection and quantification of fish populations by ultrasonic echo ranging

Abstract

The discovery that fish schools could be detected by ultrasonic echo ranging led to early utilization of hydroacoustic equipment by fisherman and fisheries scientists. However, the full potential of ultrasonic echo ranging for quantitative fisheries investigations has only recently begun to be realized. At the University of Washington a concerted effort to develop and apply hydroacoustic methods in the study of fish populations was initiated in the late 1960's. Investigations have been conducted on the relationship between echo intensity and fish abundance and on scattering characteristics of fish targets. Equipment and techniques which were developed as part of this research are now being applied by fisheries managers on several fish stocks in the northeastern Pacific and in scientific investigations of the role of fish in both freshwater and marine ecosystems. [Work supported by Sea Grant and IDOE.]