Evaluating uncertainty in measurements of fish shoal aggregate backscattering cross-section caused by small shoal size relative to beam width

The aggregate backscattering cross-section, σag is the sum of backscattering cross-sections of all fish in a shoal. It is a basic acoustical parameter used for shoal description and biomass estimation. Simulations were undertaken for evaluating the impact of horizontal dimension, density, depth and beam width on measurements of σag for shoals with constant abundance. The important factor determining measurement bias is the ratio of shoal size...