ABSTRACT
This chapter shows how the major characteristics of fish-finding instruments are determined and to what extent they satisfy the requirements. It considers a rational choice of the major parameters of acoustic instruments. The possibilities of detecting concentrations in some commercial fishing area depend, largely, on the detection range of the employed acoustic instruments. The detection range of an echo sounder should ensure the registration of fishery items down to the maximal depth of their habitation. Estimating the detection range of an acoustic instrument is made with respect to a specific standard target. In determining the required detection ranges of acoustic instruments, it is necessary to take into account the specific peculiarity of item distribution by depth. The chapter also considers detection zones of fish-finding instruments regarding various commercial items. Special attention should be paid to the influence of the acoustic characteristics of fish on detection zones.
