ABSTRACT
The search is a step of the process of reconnaissance, which represents a number of operations aimed at detecting commercial concentrations. In searching for concentrations, when great regions of the sea must be investigated, one first tries to find water areas with favorable conditions for habitation of commercial items. Research and fishing vessels perform an acoustical search to an equal degree. The chapter considers the tactics of the acoustic search and examines the general forms of distribution of fish and other aquatic organisms. Acoustic instruments register fish and other organisms distributed dispersedly as a great number of individual specimens. Scattering layers of noncommercial items have well-pronounced daily vertical migrations. Commercial items may maintain dispersal within the period of feeding if food organisms are distributed over a wide area. Distribution of commercial items by water areas is determined by the physical conditions in the water body, the food sources, the abundance of items, their physiological state, and so on.
