Duration:  1 to 21 October 2024

Cruise area:  Western Baltic Sea including Belt Sea, Kattegat, Öresund and Arkona Sea

Purpose:  Hydroacoustic survey of pelagic fish stocks

The annual cruise (GERAS- German Acoustic Autumn Survey), which is organised in cooperation with Denmark, is part of an international hydroacoustic survey of pelagic fish stocks in the Baltic Sea coordinated by ICES (BIAS - Baltic International Acoustic Survey). Vessels from Estonia, Latvia, Poland, Russia and Sweden are also taking part in this survey.

In addition to the hydroacoustic recording of pelagic fish stocks, the following tasks are to be fulfilled:

1.    calibration of the echo sounder system (carried out in advance)

2.    biological sampling: fishing hauls to identify the echoes, record the length distribution, age structure and species composition.

3.    hydrographic investigations: measurements of vertical profiles of temperature, salinity and oxygen concentration.

4.    comparative survey in the Öresund: clarification of whether the survey area in the Öresund is still representative of the spatial distribution of the herring population there.