This dataset presents fisheries acoustic data in both proprietary Simrad raw format and international HAC format recorded onboard R/V Thalassa on 28/04/2013 between 14:56 and 15:16 GMT near the continental shelf edge in Southern Bay of Biscay. Data include typical small pelagic fish schools composed of anchovy and sardine encountered in springtime in this area. The dataset has also been converted to international Sonar-netCDF4 format described at : https://github.com/ices-publications/SONAR-netCDF4 HAC files can be displayed and processed using e.g. the MOVIES3D freeware provided by Ifremer at: http://flotte.ifremer.fr/fleet/Presentation-of-the-fleet/Logiciels-embarques/MOVIES Sonar-netCDF4 files can be displayed using standard netCDF viewers and Python notebooks available at : https://gitlab.ifremer.fr/fleet/formats/pySonar-netcdf