Studies on Echo Counting for Estimation of Fish Stocks-II

The total amount of fish stocks could be estimated from data obtained by the S-type echo counter. The results of the trial calculations are: 1. The densities of densely concentrated fish schools are 1.84 to 76 fish per 1m3 around the waters off Koyama-Misaki. 2. The total amount of fish stocks is given as 590×106 anchovies of 9cm in length, and 5, 300 tons when the body weight is 9g per fish. 3. From the power spectrum of fish density index, Ni, it is estimated that the geographic distribution of fish schools is of a clustered nature and the relative distance of densely concentrated fish schools may be more than 1, 000m. 4. Errors of the echo counting system could not be clarified. Deep and careful attention should be paid to the caribrations of the acoustic, electronic and mechanic circuits, because errors in estimated value is directly due to that of the counting system.