This dataset illustrates a study of the trawlable seabed of the Gulf of Lion, which took place over four years between 1957 and 1960. An inventory of the bentho-demersal community was carried out by bottom trawling. Measurements of total weight and length were taken as well as sex determination. This study was carried out with the research vessel Président Théodore Tissier up to 1959 and with the research vessel La Thalassa in 1960. In 1957, the objective was to roughly evaluate the trawling possibilities on the French Mediterranean coast between 200 and 1,000 metres. This was furthered in 1958 to evaluate the inter-annual yield variations, compare the yield from daytime and night-time fishing and make observations on the nature and density of the fauna on the continental shelf in the Gulf of Lion. In 1959, the objective was to study the fishing possibilities on the southern coasts of the western basin, from Ceuta to the Strait of Sicily. In 1960, the objective was to obtain additional information on the trawlable bottoms of the Languedoc region as well as some references on the Balearic region.