Duration of the cruise:  25 March to 26 April 2025

Cruise area:  West British Waters (EU)

Purpose of the cruise:  Mackerel and horse mackerel egg surveys

North-east Atlantic mackerel (Scomber scombrus) is one of the most important fish stocks for European fisheries in terms of the value of landings. The central task of the survey is to determine their spawning biomass, which is estimated by determining the concentration of freshly spawned eggs and the fertility of the females and their proportion of the total population. Due to the enormous temporal (January to August) and spatial (Gibraltar to the Faroe Islands) extent of the spawning business, this survey has only been carried out every three years since the 1970s. Since then, it has provided a reliable index for the stock size of mackerel. Since the 1990s, the survey has also provided an index for the stock size of the horse mackerel (Trachurus trachurus), another important fish species for European fisheries. Eight European nations are taking part in the study, which is coordinated by the International Council for the Exploration of the Sea. Research vessels as well as fishing vessels chartered for the survey spend a total of more than 300 days at sea.

As a German contribution, the chartered Greenlandic fisheries research vessel "Tarajoq" will spend five weeks sampling the western European shelf west of Ireland and in the Celtic Sea during the expected main mackerel spawning season (this voyage replaces the originally planned 488th voyage of the Walther Herwig). At least one plankton sample is taken in selected statistical semi-rectangles using a vertical haul with the "Nackthai" plankton trap. In addition, targeted net catches of adult animals in the spawning area are carried out to obtain information on length, age, sex and maturity composition and to determine the fecundity of the mackerel.

Cruise report (PDF)