The Pélagiques Gascogne (PELGAS, Doray et al., 2000) integrated survey aims at assessing the biomass of small pelagic fish and monitoring and studying the dynamics and diversity of the Bay of Biscay pelagic ecosystem in springtime. PELGAS has been conducted within the EU Common Fisheries Policy Data Collection Framework and Ifremer’s Fisheries Information System. Details on survey protocols and data processing methodologies can be found in Doray et al., (2014, 2018). This dataset comprises the abundance (no. of individuals), biomass (metric tons), mean length (cm), mean weight (g) of marine organisms collected by midwater trawling to identify fish echoes detected during PELGAS surveys (2000-2018). All parameters have been raised to the trawl haul level. Trawl haul metadata and species reference list are also provided.