This study was aimed to measure the acoustic impedance as a dominant factor to estimate the amount of fish resources for fisheries resource rebuilding program of jack mackerel. The fish’s acoustic impedance is one of main factors for TS measurement....
This study was aimed to measure the acoustic impedance as a dominant factor to estimate the amount of fish resources for fisheries resource rebuilding program of jack mackerel. The fish’s acoustic impedance is one of main factors for TS measurement. The acoustic impedance needs to know sound speed contrast and density contrast of target fish. The density contrast was carried out by the Pipette method and the sound speed contrast was measured by the Time-of-flight method. To obtain sample information of jack mackerel in the experiment, 20 individuals used. Its body length and weight were measured by using an electronic scales and body length measure plate. As a result, the body length of the jack mackerel increases the weight also increases. There was low correlation with body length and density. Additionally, acoustic speed contrast tended to decrease with increased water temperature. To reduce the measured error of the TS measurement, it is necessary to apply a suitable sound speed contrast and density contrast of jack mackerel to the distributed water condition.