The Goldys project (Seasonal Dynamics of the Gulf of Lion, 2021-2023) aims to obtain a better understanding of the life cycles, spatial distributions and dynamics of exploited populations via seasonal monitoring of the resource. By collecting standardized observations throughout the year, it completes the summer vision of the system obtained through yearly scientific surveys deployed in June by Ifremer during the MEDditerranean International Trawl Surveys (MEDITS). By relying on the same protocols and observation devices as MEDITS (to allow seasonal comparison) but by deploying them from a Mediterranean trawler (Vaz et al., 2023a), it aims to observe the seasonal evolution of all demersal or benthic species caught by bottom trawls and the reproductive cycles of a large number of them. A total of 40 operations per season, spanning 75 days at sea, were carried out between April 2022 and March 2023. This information may be used to define the spawning periods and map spawning and nursery grounds. The data obtained make it possible to answer certain questions on the ecological functioning of the Gulf of Lion and the seasonal dynamics of species exploited by trawl fleets (Vaz et al. 2023b).