GOLDYS bottom trawl surveys catch data : Bentho-demersal assemblages of the Gulf of Lion (North-western Mediterranean) in 2022-2023

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).


Fisheries and aquaculture, Biological oceanography, Environment


Gulf of Lion, North-western Mediterranean, demersal fish, benthic invertebrates, seasonal dynamics, exploited species, MEDITS


43.6N, 42.4S, 5E, 3W


On an established methodological basis, using the MEDITS protocol, half-hour bottom trawls are carried out using a standard scientific trawl used since 1994 on all European bottom trawl surveys (Spedicato et al., 2019). It was implemented in accordance with the recommendations described in the MEDITS handbook (MEDITS WG, 2017) using a reduced mesh size (20mm stretched) in the cod-end allowing for the capture of juveniles. Representative sub-samples of the catches were brought back to the laboratory to allow sorting, identification, counting (except for colonial invertebrates) and weighing of all the species captured and to carry out individual biological monitoring for some of them (size, weight, sexual maturity) using the sampling strategy, tools and methodologies detailed in Vaz et al. 2023a.

The data is in the ELevated FIsh Catch (ELFIC) format, were all sub-sample observations were elevated to the level of the total catch in the catch table. It is also strongly recommended to standardise catch values per km² or per hour as haul duration, gear geometry and swept area may vary from one observation to the next.

We also recommend this dataset to be analysed in conjunction with the MEDITS 2022 data to complete it with spring and summer 2022 observations.

The present dataset is composed of a pdf document describing the structure and content of each file, and 5 csv files containing the metadata and data.


description of structure and content of each file
Metadata and data files
4 MoCSVProcessed data
How to cite
Vaz Sandrine, Certain Gregoire, Hattab Tarek, Jadaud Angelique, Villeneuve Remi, Raphalen Elio, Metral Luisa, Cheret Isabelle, Bourdeix Jean-Herve, Tessier Emmanuel, Bassinet Emmanuel (2023). GOLDYS bottom trawl surveys catch data : Bentho-demersal assemblages of the Gulf of Lion (North-western Mediterranean) in 2022-2023. SEANOE.

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