Backscattering cross section is a property of an object that determines what proportion of incident wave energy is scattered from the object, back in the direction of the incident wave.
In physics generally, it is defined as the area which intercepts an amount of power in the incident beam which, if radiated isotropically, would yield a reflected signal strength at the transmitter of the same magnitude as the actual object produces.
In fisheries acoustics, the same term is used to mean the same area but divided by 4ÃÂ. In other areas of underwater acoustics, the general physics definition is used.