International Bottom Trawl Survey (NS-IBTS2024-Q1) - French cruise report –

In 2024, the French NS-IBTS Q1 survey was conducted as part of the International Bottom Trawl Survey program carried out by main countries bordering the North Sea in order to assess abundance and stocks distribution, independently of commercial fisheries data. The first target of the NS-IBTS Q1 survey is to provide a diagnosis on the main commercial fish species by estimating their abundance per age. A standardized protocol is rigorously applied by all participants. The R/V Thalassa sampled the eastern part of the Channel and southern North Sea (until 55° N) from 20th January to 9th February 2024. During daily time, 50 hauls, lasting 30 minutes, have been carried out with a GOV bottom trawl. All collected species have been collected, determined and measured, 1916 otoliths (for age estimation) have been collected for 10 species, and 550 stomach (for trophic informations) have been collected for 4 species. This year, whiting (Merlangius merlangus) represented 60% of the total biomass caught followed by herring (Clupea harengus; 21%) and mackerel (Scomber scombrus; 9%). During the night, 89 MIK net have been deployed to calculate an index for herring, sardine and lemon sole larvae abundance. Within each station, a CTD sensor was deployed to record environmental parameters (e.g., temperature, salinity and oxygen) all along the water column, from surface to bottom. In order to study the whole marine ecosystem, some additional studies were carried out in the context of the Marine Strategy Framework Strategy and for various research projects.


North sea, GOV, bottom trawl, MIK, abundance, stock assessment.


63.582229N, 49.218262S, 9.987772E, -5.112112W

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Bled--defruit Geoffrey, Caboche Josselin, Auber Arnaud (2024). International Bottom Trawl Survey (NS-IBTS2024-Q1) - French cruise report –. Ref. RBE/HMMN/RH 2024-1. Ifremer.

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