Dana on a monitoring cruise in the North Sea, Skagerrak and Kattegat

The research vessel Dana is on the Herring Acoustic Survey to collect data on herring and sprat, which are important stocks in commercial fisheries.

Dana at sea. Photo: Susan Mærsk Lusseau.

From 1 to 14 July 2025, the research vessel Dana is on the Herring Acoustic Survey (HERAS), which is coordinated by the International Council for the Exploration of the Sea (ICES).

The survey is conducted annually from the end of June into July by research institutes from Scotland, Germany, the Netherlands, Norway, Ireland and Denmark. Over this period the whole of the North Sea, Kattegat and Skagerrak as well as the shelf seas North and west of Great Britain and Ireland is covered, providing a snapshot of all herring and sprat stocks in the area.

What data is collected?

Data is collected using hydro-acoustics along pre-planned transects and short-term fishing on fish aggregations encountered. Data is used to map distribution and estimate biomass as well as size, age and maturity composition of the herring and sprat stocks. In addition, hydrography and plankton data is collected to help explain the distribution of herring and sprat.

What is the data used for?

Data from the countries' surveys is collated and processed in an ICES working group. The results are turned into ICES' biological advice on the state of herring and sprat stocks. This advice is targeted at the authorities, who use it as a basis when setting fishing quotas and other rules for fisheries.