To improve the accuracy of abundance estimates from acoustic data, it is necessary to determine the catch efficiency of the sampling gear used in combination with the acoustic survey. In this study, we proposed a method to estimate the catch efficiency of framed midwater trawl（ FMT） using acoustic data for juvenile walleye pollock （Gadus chalcogrammus）, one of the dominant species of sound scattering layer in south east area of Hokkaido. Experimental hauls using FMT with black netting were conducted 17 times in nighttime, as a result, juveniles of fork length ranged from 10 to 70 mm was caught. The estimated efficiency by each haul decreased with the fork length increases with sampling periods. Additionally, the efficiency was estimated by the fork length class of 10 mm intervals using multiple regression, then its variation with length showed same tendency with the result mentioned above.
