This file contains data on numerical abundance of larvae and transforming stages of fishes collected during the CSIC-SUMMER survey carried out in October 2010 in five zones around the Iberian Peninsula: Balears and Alboran in the western Mediterranean, and Cadiz, Lisboa and Galicia. Hauls were carried out day and night to study horizontal and vertical distributions of fish early stages using a the multinet net system MOCNESS_1, fitted with meshes of 0.2 mm. Samples were taken in 18 stations at eight layers of the water column, amounting a total of 136 samples. Plankton samples were preserved in buffered formalin (5%) and fishes were sorted out and identified, to the lower possible taxa, in the laboratory. These data were obtained within the European Union Project 'Sustainable Management of Mesopelagic Resources' (SUMMER, Grant Agreement 817806) as funded by the Horizon 2020 Research and Innovation Programme.