Duration: 5 to 21 August 2025

Area: North Sea

Purpose: International Bottom Trawl Survey (IBTS)

The cruise is part of the IBTS, which is an internationally coordinated ICES (International Council for the Exploration of the Sea) program aiming to provide fish population data and biological parameters of commercial and non-commercial fish species for stock assessment purposes.

The aim of the survey is to provide the ICES assessment and scientific groups with consistent and standardised data for stock assessment purposes. The study will examine spatial and temporal changes in (a) the distribution and relative abundance of fish and fish groups and (b) the biological parameters of commercially exploited fish species.

The cruise has been moved from the German FRV Walther Herwig III to the Danish RV Dana. Fish sampling will be carried out by demersal trawl hauls in allocated ICES statistical rectangles. In parallel, epibenthos (= organisms living at the sea ground), the infauna (= animals living in the sediments) and sediments will be analysed and hydrographic and marine chemical parameters recorded. Time series analyses over several decades of the survey are used to quantify long-term changes in the faunal (= animal) communities, especially in connection with climatic change and other human influences.

The main objectives are to:

• determine the distribution and relative abundance of pre-recruits (= juvenile phase of an organism's life cycle) of the main commercial species with a view of deriving recruitment indices
• monitor changes in the stocks of commercial fish species independently of commercial fisheries data
• monitor the distribution and relative abundance of all fish species and selected invertebrates
• collect data for the determination of biological parameters for selected species
• collect hydrographical and environmental information

Cruise report (PDF, englisch)