Living Marine Resources

Frisch gefangener Ostseedorsch mit typischer Zeichnung und charakteristischer Bartel am Unterkiefer — Freshly caught Eastern Baltic cod with typical markings and characteristic barbel on the lower jaw.

For sustainable management of the renewable resource marine fish, we need basic knowledge about the ecology and productivity of the stocks, but also data on distribution and removals, as well as suitable calculation models.

The sustainable use of commercial fish stocks in the Baltic Sea is one of our central research goals. How can we manage fish stocks in such a way that enough fish remain in the sea to ensure offspring for future generations of fish and fishermen?

The Baltic Sea, as the world's largest brackish water sea in one of the most highly developed economic regions on earth, is a magnificent open-air laboratory for science, including fisheries biology. Here we study the life cycles of all commercially important fish species, their interactions with fisheries and the environment, and further develop stock models. The most important commercially exploited fish species in German fisheries in the Baltic Sea are cod, herring, sprat and the flatfishes plaice, flounder, dab and turbot. The fish stocks have adapted to the hydrographic characteristics of the different basins within the Baltic Sea over thousands of years. We try to understand how the fish and fish stocks react to current biotic and abiotic influences, to changes in these factors and to the influence of fishing. To do this, we conduct elaborate research trips (monitoring) and sample commercial fisheries to obtain the most accurate data possible on the removal of fish from a stock. In addition to classical data collection, we conduct research on applied topics in fisheries biology.

Modelling and stock size estimation

Population models are our most important tool to estimate the status of commercially used fish stocks and to forecast future developments.

Stock separation

Stocks mix at the borders of their distribution areas. If our population-specific calculations are to be reliable, we must even be able to assign individual animals to their respective populations.

Food webs and habitat use

Food also determines the growth of fish - and thus has a direct influence on future fishing opportunities. In the Baltic Sea in particular, habitat use is also determined primarily by physical parameters.

Other mortality factors

In our calculation models we distinguish between natural and fishing mortality. The latter mainly includes landings, but also fish that are discarded dead or those that escape from the nets but are so injured that they die later.