Characterization of underwater organisms using ultrasonic inspection techniques in reverberant cavity

Characterization of underwater organisms by ultrasonic techniques has been under development. It is a harmless technique to monitor underwater organisms. In a previous study, ultrasonic measurement was used to monitor non-invasively the number of fishes and even growth rates in the future that under highly reflecting boundaries. These measurements were performed remotely, without human interaction with the fish. Recently, it has been demonstrated that the acoustical total scattering cross section of fish swimming in a basin can be measured from multiple reverberation time series. These measurements have been used successfully to estimate the number of fish in a tank in laboratory conditions. n this thesis, a reference study of correctness and accuracy was made with the measurement of the total target strength of solid metal balls. After the confirmation of the accuracy of the study, the above basic theory mentioned was applied. Different kind of species (such as Shubunkin Goldfish, Neon Tetra fish and Golden Zebra fish) was used as the organism measured to identify the characteristic signals magnitude in the study. Further, the calculation of the different number of fish corresponded total target strength was made. Finally, the measurement of corresponded total target strength to the three species of fish was made. By these information, an effective species database was established.