Analyzing zooplankton size distributions using high‐frequency sound

A high#x2010;frequency, dual#x2010;beam acoustical technique for directly estimating the size distributions within zooplankton assemblages has been developed. In combination with data from echo integration, acoustical size distributions can be used to apportion zooplankton numerical density and biomass concentration into different size classes. Two major conclusions can be drawn from calibration experiments and preliminary field studies using the technique: the backscattering intensities from individual zooplankters increase proportionally with the cubes of their lengths; and the combination of dual#x2010;beam and echo#x2010;integration techniques has the potential to produce rapid, high#x2010;resolution, size#x2010;specific data on zooplankton distributions in the water column.