Five evaluation cruises ler pelagic resources were performed between April1997 September 1998 on Peruvian coast, these allowed to observe changes in composition by species, distribution, size structure, reproduction, and population levels. These changes are similar to those observed in both El Niño 1972-73 and 1982-83, specially with respect to anchovy biomass decrease and increase 01 other pelagic species. Considerable changes in anchovy size structure in post-Niño period was observed, while sardine, samasa and Pacific mackerel showed good recruitment. Also the reproductive activity was increased, even in juveniles, with outstanding proliferation 01 sexual mature sardine with 18-20 cm length, this situation has not been recorded before.