Dana on a survey in the North Sea

From 11 to 22 June 2025, the research vessel Dana is participating in the International Mackerel Egg Survey (MEGS), which is coordinated by the International Council for the Exploration of the Sea (ICES). The survey is conducted every third year.

As mackerel are spawning over a vast area in the eastern Atlantic from Spain to Iceland, a number of different countries and research vessels are participating in these surveys. Dana’s task is to collect samples in the North Sea, in close collaboration with British colleagues from the Centre for Environment, Fisheries, and Aquaculture Science (CEFAS).

Which data is collected?

Data is collected by hauls with a high-speed plankton sampler, a so-called “Nackthai”. The gear is deployed on a fixed grid of stations with regular spacing to collect mackerel eggs. The eggs are sorted into different developmental stages and counted to obtain abundance estimates.

In addition, adult mackerel are caught by pelagic trawling to obtain data on their sex, age, length, weight and maturity and to collect tissue samples of the ovaries. These samples are then analyzed in the laboratory on land to investigate how many eggs a female of a certain size can produce.

Furthermore, data on oceanographic conditions such as temperature and salinity are collected, which can help to interpret the survey results.

What is the data used for?

The data from the participating countries' cruises are collated and processed in ICES. By combining the data on eggs and adults, estimates of the mackerel stock size can be obtained. The results are used in stock assessment and are contributing to biological advice on the state of the mackerel stocks. This advice is targeted at the authorities, who use it as a basis when setting fishing quotas and other rules for fishing. 

Where is Dana now?

• See the research vessel Dana's current position