Duration: 24 February to 20 June 2025

Shipping area: Baltic Sea (Greifswalder Bodden, Strelasund)

Purpose:  Rügen Herring Larval Survey (RHLS)

As part of the long-term series of the RHLS, which has been monitoring the recruitment success of spring-spawning herring in the western Baltic Sea since 1977, the occurrence and spatial distribution of the larvae of the "Rügen herring" is to be recorded. The aim of this survey is to obtain an up-to-date recruitment index from the data obtained on larval distribution and abundance in the Greifswalder Bodden and Strelasund spawning grounds. This provides information on the year-class strength of herring recruitment in the western Baltic Sea and is used to predict stock development.

Sampling includes weekly trips for standard sampling to quantify herring larvae using plankton gear and hydrographic probes. In the remaining days of each week, further investigations are carried out on herring in the Bodden as part of the BMBF project SpaCeParti II. These include sampling of advanced larval stages and successive spawning cohorts. At the beginning of the spawning season in February to April, occasional hydroacoustic recordings of the herring distribution in the Sassnitz channel are planned, as well as a few trips to the Oder Bank for video analyses of the fish fauna if possible.