Comparison of the Distribution of Demersal Fish Biomass Determined by Bottom Trawl and Hydroacoustic Surveys in the Northern East China Sea in Winter, 2014

This study examined the spatiotemporal distribution of demersal fish aggregations in the Northern East China Sea by conducting a trawl survey with hydroacoustic devices. A bottom trawl was used for this survey and fish density was determined from the catch data. Acoustic data were collected at frequencies of 38 and 200 kHz from November to December 2014 and converted into the nautical area scattering coefficient (NASC, $m^2/n{\cdot}mile^2$ ). In the catch data analysis, the range of catch per unit area by station was $26-8,055kg/km^2$ and for the acoustic data, that of the NASC was $0.45-34.80m^2/n{\cdot}mile^2$ . The values were significantly correlated. The combined results of both surveys found that the density was highest at St. 5 ( $33^{\circ}$ 10.3', $126^{\circ}$ 23.3') and lowest at St. 8 ( $33^{\circ}$ 20.7', $127^{\circ}$ 36.3'). The application of hydroacoustic methods offers a new approach for estimating the biomass of demersal fish aggregations.