Analysis of herring and sprat stock structure
Herring and sprat play a central role in the Baltic Sea ecosystem. Following decades of intensive fishing, stocks have declined, which may have consequences for the food chain in the inland sea. To avoid overfishing local stocks, a good understanding of stock structure is required, i.e. the presence of different stocks and their migration patterns.
Herring shows significant adaptation to local conditions and can be divided into many stocks with distinct genetic differences. However, there are gaps in our knowledge regarding how many stocks exist in the Baltic Sea and how stable they are over time. The stock structure of sprat is considerably less well understood; here, there is a lack of knowledge as to whether there are few or many stocks in the inland sea.
Large-scale fishing takes place in the Baltic Sea. Around 90 per cent of the fish caught in Swedish waters is herring and sprat. Only 10 per cent of the catch is used for food; the rest is used to produce fishmeal for animal feed. Without knowledge of the stock structure of these species, large-scale feed fishing risks depleting entire stocks.
To contribute knowledge that enables more sustainable management of herring and sprat, the project Analysis of the stock structure of herring and sprat will do the following:
- Map the stock structure of herring in the Baltic Sea using high-resolution genetic mapping of samples collected during spawning along the entire Swedish Baltic coast. The project will also carry out a detailed study of two areas of particular importance for herring and sprat fishing – Hanö Bay and Gävle Bay.
- Genetic mapping of sprat stocks in the Baltic Sea based on approximately 5,000 specially selected genetic markers and, to some extent, by mapping the entire genome of the collected fish.
The project’s main funder is BalticWaters and it is being carried out by Uppsala University, the University of Gothenburg, Stockholm University, SLU Aqua and the Marine Centre in Simrishamn.
Project materials
Scientific article: The population structure in the Baltic herring reflects natural selection and local adaptation (2026-03-09)
Article: New fast-growing herring discovered – what does this mean for the Baltic Sea? (2025-01-20)
Sveriges radio: New type of herring discovered – predatory herring (2024-12-24)
Scientific article: Evolution of fast-growing piscivorous herring in the young Baltic Sea(2024-12-23)