On acoustic identification, sizing and abundance estimation of fish

Abstract

A method using the fish angle (i.e. the change in target strength with fish aspect) for identification purposes is described. Significant differences in fish angle between cod and coalfish have been observed at sea. The effect of fish angle on the sampling volume of an echosounder is discussed, and it is shown that the sampling volume decreases with decreasing fish angle. A method for abundance estimation applying an echo integrator is described and discussed.