Pelagic schooled fish populations have acoustic characteristics derived from their individual reflection or backscattering properties, their tendency to school, the tendency of schools to be aggregated in groups, and the tendency for populations of different species to be aggregated in regions of high productivity. In addition to those static properties, the different species populations can be expected to have characteristic swimming and feeding behavior at the individual level and foraging behavior at the school level. Schooling-level foraging behavior is affected by the fact that a school of fish eats far more than is produced per unit of school area. The foraging behavior of schools is expressed as the number of unit areas to be grazed per unit of school area. For example, a moderately compact school of anchovy (0 dB target strength) might contain 15 kg of fish per square meter of sea surface. Food requirements of such an aggregation probably exceed 40 g C/m2/day but primary productivity of the northern anchovy is only of the order of 0.5 g C/m2/day. Therefore, an individual anchovy school must cover a minimum of 80 times its own area each day. Other fish species appear to school in less compact schools and probably have other food requirements. Schooling and foraging behavior also differs by day and night. Work in California waters has demonstrated acoustical techniques for the estimation of fish size and school motion. These acoustic parameters remain to be combined with static and dynamic, biological and geographic knowledge of fish populations to provide practical acoustic means of fish target identification. Similarly, the acoustic characterization of water masses and particularly the distribution and abundance of epipelagic schooled fish targets which we are investigating appear to be lacking for most of the world ocean in the upper 100 m.