Species and size-class discrimination of selected fish using broadband sonar

Abstract

A sonar system was designed and built that could transmit and receive a broadband signal. This transmission takes the form of a chirp, ranging in frequency from 50–150 kHz. Four species of fish represented by ten size classes were used in a laboratory environment as targets. An acoustic signature was developed for each of the species and each of the size classes within each species. Pattern analysis techniques were then employed to test unknowns against these signatures. The system as a whole was capable of 95% accuracy in both species and size class discrimination. (Those fish misclassified to specie were considered to be misclassified to size irrespective of the relative sizes of the signature and unknown.) Size-class accuracy is approximately ± 10% of the fork length of the fish. Hydroacoustic and pattern recognition techniques are presented.