NourDem scientific cruises consist of sampling in estuarine and coastal sectors using the GOV trawl (Large Vertical Opening) "Ifremer / NourDem 11.90-16.45m". This trawl is operated from small professional trawlers, about ten meters in length and less than 2 meters in draft, so as to be able to sample the most upstream sectors of the estuaries (down to zero of salinity), including the foreshore area at high tide, areas where nurseries are located for many species (case of sea bass Dicentrarchus labrax or sole, Solea solea, for example). When fishing, this trawl sweeps the seabed over a width of around 7m, and its vertical opening is between 2.20m and 2.40m.

The aim of these cruises is to produce annual abundance indices for the main species living in the estuary, which can be used :

• either locally, by local managers (Marine Parks, GIP, Communities of communes, etc.) as part of their monitoring, preservation, information/knowledge dissemination missions;
• or by the ICES (International Council for the Exploration of the Sea) working groups, in charge of assessing the state of exploited stocks and drawing up management recommendations on behalf of the European Union and the Member States.

The cruises last 8 days each, which allows about 70 trawl lines to be taken depending on the sector.

The data produced are "public" and therefore usable. It is then necessary to mention the partnerships and projects that enabled their acquisition.
The data were acquired as part of the "NourDem Seine 2017" project. This project was financed by the Comité Régional des Pêches de Normandie, the Comité Régional des Pêches Maritimes et Elevages marins des Hauts de France, the Producer Organisations OP CME, OP Normandie, OP COBRENORD, OP FROM Nord and OP Pêcheurs de Bretagne, as well as by Ifremer. Ifremer was in charge of the project, with the Comité Régional des Pêches Maritimes de Normandie acting as assistant to the project owner.

All requests for campaign data should be made to Ifremer's Harmonie desk at the following address harmonie@ifremer.fr