2周波を用いた動物プランクトンの音響計測に関する研究

抄録

We examined two methods for acoustical estimation of zooplankton abundance using the high-pass sphere model and two frequencies. Frequencies were 50 kHz and 200 kHz. In Method 1, the body length of the zooplankton, which is necessary to estimate the biomass density, was derived theo-retically from the difference of volume back-scattering strength (SV) at two frequencies. In method 2, this information was obtained by actual net sampling. Method 1 was useful to estimate size and bio-mass approximately in the survey area. Method 2 was useful to estimate biomass closely when biolog-ical compositions were simple. Both methods can be applied to acoustic observations of macro zooplankton by common echo sounders mounted on research vessels.