Target strength
The target strength or acoustic size is a measure of the area of a sonar target. This is usually quantified as a number of decibels. For fish such as salmon, the target size varies with the length of the fish and a 5 cm fish could have a target strength of about -50 dB.
Target strength is equal to 10 log10 dB, where σbs is the differential backscattering cross section. Backscattering cross section is 4πσbs.
