The book represents a collective investigation of the members of Plankton Laboratory of the Institute of Oceanology of USSR. The study discusses data which were obtained by research vessels Vityaz' and Ob'. These data are compared with the data published in oceanographic literature both domestic and foreign. The samples were obtained by the nansen bathometer, three types of Juday net, ring trawl and Isaacs-Kidd trawl. The objective of the study was the determination of general pattern of plankton distribution by areas and depth levels, and the variation of plankton by seasons and years. Areas with high and low productivities are singled out, describing the geographical and ecological zones of the Pacific Ocean. (Author).