Dana is on a monitoring cruise in the Norwegian Sea

The research vessel Dana is in the Norwegian Sea to collect data on Atlanto-Skandian herring and blue whiting, both important commercial fisheries stocks.

View through a porthole on Dana. Photo: Line Reeh.

From 22 April to 16 May 2025 the research vessel Dana is taking part in the International Ecosystem Survey in the Norwegian Sea (IESNS). The cruise is a collaborative cruise between EU nations with quota in the Atlanto-Skandian herring fisheries and is carried out with participation of scientist from Denmark, Germany, Ireland, Sweden and Netherlands.

In addition to Dana, vessels from Norway, Iceland, Faroe Islands and the UK participate in this large-scale survey and most of the Norwegian Sea is surveyed during April-May each year. The IESNS has been carried out annually since 2004 with DK/EU participation.

The survey is coordinated by the Working Group on International Pelagic Surveys (WGIPS) under the auspices of the International Council for the Exploration of the Sea (ICES).

What data is collected?

The survey is an acoustic trawl survey using scientific echosounders along pre-determined transect lines to collect information on the abundance of herring and blue whiting. Species verification and biological samples of herring and blue whiting are collected by pelagic trawling with a small midwater trawl on aggregations of fish detected acoustically. Information on size and ages are collected from these fish.

Plankton samples are collected at stations placed 60 nautical miles apart along the transects and at the same stations hydrographic data (temperature and salinity) is collected with a CTD from 0-1000 meters depth.

What is the data used for?

The aims of the survey are to map the distribution of and provide indices of abundance of Atlanto-Skandian herring and blue whiting in the Norwegian Sea for use in the stock assessments of these species carried out in ICES. The results from this are turned into biological advice on the state of these commercially important fish stocks. This advice underpins the management of Atlanto-Skandian herring and blue whiting stocks.

The survey also contributes to the monitoring of the hydrographic and plankton conditions of the Norwegian Sea and adjacent waters for studies on how feeding, distribution and migration of herring and other pelagic fishes are influenced by these conditions.