HyFiVe-Baltic

Background and Objective

The Baltic Sea is changing. Examples include rising water temperatures and temporary oxygen depletion, even in shallow water areas, with corresponding effects on the ecosystem and fish stocks. This ecosystem is very sensitive and reacts more quickly and more significantly to climate change and overfertilization than, for example, the North Sea.

Hydrographic parameters such as temperature, salinity, and oxygen content are important indicators for assessing the condition of a sea. Fish species can only recover if these parameters are within certain limits. However, more data with good temporal and spatial resolution is needed to better understand the changes and the underlying processes. Conventional research vessels reach their limits here, especially in shallow coastal areas.

Approach

The market survey for the project is complete. We were looking for fishermen and women who are willing to contribute their experience and expertise to the conduct of research work. This involves carrying out measurements with the HyFive measurement system on one or more of the depicted transects using their own fishing vessels (the measurement system is provided by the Thünen Institute for Baltic Sea Fisheries, and requires a 12V DC or 230V AC power supply on board).

The data collection is carried out in close collaboration with the scientists from our institute. The specific procedure for the measurement is explained in the chapter "Data and Methods". Based on the registration information, we will now review and evaluate the applications and prepare the tendering process internally. Subsequently, we will contact all interested parties and conduct the formal tendering process with the companies that are suitable for us, during which the remaining details will also be discussed. Please note that this process will take some time.

After completion of this process, the corresponding contracts will be created. We are currently planning to start the measurements in January 2026. If you have any further questions or concerns, please do not hesitate to contact us (sascha.winkler@thuenen.de ). We look forward to the cooperation with our partners and to the successful implementation of the project.

Data and Methods

The measurements will be taken at specified sections (transects) with 6-10 stations each. At each station, the measuring probe is slowly lowered to the seabed using a rope and then hoisted back up. Each transect begins near a port in order to keep travel distances as short as possible. Sampling should take place weekly if possible. However, the sampling plans can be adjusted in consultation in the event of bad weather, holidays, and layovers. The measurement trips can be combined with other operations/trips, including fishing, as long as the scheduled time frame for the measurement is adhered to.