A Dual-Beam Acoustic System for Measuring the Target Strength of Individual Fish

A dual-beam sonar system has been developed for making in situ measurements of the target strength of individual fish. Estimates of fish target strength distribution obtained with this system are superior to estimates obtained using other techniques. The estimates of the mean value and distribution of fish target strengths obtained with the system are used in conjunction with other acoustic techniques for assessment of fish populations. This paper gives an overall description of the system and a more detailed discussion of some of the innovative hardware and software aspects of the system´s development.