Acoustic evaluation surveys for the study of small pelagic fish in the northern Spanish coast have been conducted since 1993. These surveys have evolved into the current multidisciplinary campaigns that provide a holistic view of ecosystems and address the objectives outlined in the European Union's Marine Strategy Framework Directive. One of the primary goals of the campaign is to determine the abundance and characteristics of the main pelagic fish species (primarily sardine, anchovy, horse mackerel, mackerel, and blue whiting) using the echo integration method and mapping their distribution area. To analyze the distribution of sardine and anchovy eggs and determine the spawning area, the sampling system CUFES (Continuous Underway Fish Egg Sampler) is used since 2003. This device collects fish eggs continuously from ~3-5 m depth/under the surface) while the research vessel is moving along transects of acoustic data acquisition. This method allows for the efficient and systematic sampling of fish eggs over large areas, providing valuable data for studies on the distribution and abundance of spawning fish populations. When possible, these samples have been completed with environmental data (i. e. water temperature, salinity, fluorescence) from onboard continuous thermosalinometer. These surveys are part of the National Basic Data Program for the Fisheries Sector and respond to various international commitments for the sustainable management of our seas. To this purpose, the Ministry of Agriculture, Fisheries and Food, through the General Secretariat of Fisheries, invests efforts in the development of these research campaigns aboard its oceanographic vessels. The “PELACUS”  surveys time series is conducted in coordination with the Spanish Institute of Oceanography (IEO-CSIC). Thanks to this coordination, the Ministry of Agriculture, Fisheries, and Food facilitates the use and equipment of the ships for the research personnel and provides scientists with the most suitable instruments for the specific purposes of each survey, while striving to optimize resources for the best possible scientific knowledge to ensure effective fisheries management.