The Channel is an area with a strong fisheries influence, mainly for the coastal countries but also more widely for the countries of Northern Europe. The ecological and economic impact of the exploitation of fisheries resources must be measured so that fishing remains a sustainable activity, taking into account the limits of the resource and its effect on the environment. To meet this need, EU Member States need to carry out scientific surveys at sea to assess the abundance and distribution of stocks, independently of data from commercial fisheries. To this end, the CGFS (Channel Ground Fish Survey) campaign is part of the European Fisheries Monitoring Programme, which provides a set of data on exploited stocks (maturity, size/age structure, recruitment indices). The time series initiated in 1988 is used annually by European stock assessment groups to infer the health of the main commercial species. Initially focused on the Eastern Channel, the CGFS now aims to cover the whole Channel to provide fishery-independent data in the Western area as well.

The CGFS 2021 campaign started from Brest in mid-September, to collect fishery-independent data to assess the living marine resources in the Channel with large vertical opening trawls (GOV). For 33 days, 122 30-minute hauls were made during the day at a speed of 3.2 knots. Carried out on the N/O Thalassa, the CGFS campaign also enabled sampling and better knowledge of the entire ecosystem, meeting both the demands of ecosystem monitoring (DCSMM) and the implementation of an ecosystem approach to fisheries at Community level. Thus, the physico-chemical characteristics of the water, the phytoplankton and zooplankton communities, the abundance of fish eggs, and the specific composition of the nekton communities were measured and analysed throughout the campaign. The benthic fauna and top predators were also observed. Finally, the different types of waste were counted, and the structure of the habitat will be studied. The validated data will be transmitted at the end of the campaign to the national (SIH, Harmonie, Coriolis) and European (DATRAS) databases, which will allow their use by different working groups and will ensure public access to these data.