Baltic Herring and Herring Research

Archipelago Research Institute - Herring Research since the1980's

Research on the reproductive biology of Baltic herring was started at the Archipelago Research Institute and the Department of Biology of the University of Turku in the beginning of the 1980's. Since that, herring research has continued in the form of several scientific and monitoring projects that have been carried out in the Archipelago Sea area, and especially at the vicinity of the City of Turku, where one of the major herring reproductive areas is situated. The data are based on field sampling of the spawning fish, and direct monitoring of the spawning beds by scuba diving. During this three-decade biological survey, the environmental conditions of the spawning area have changed considerably, e.g due to eutrophication and decreasing salinity of the Baltic Sea.

These pages present some results of this project, and also provide general information on Baltic herring, which, despite of its small body size, is an important component of both the Baltic ecosystem as well as the Baltic fisheries.

Baltic Herring and the Archipelago Sea

Herring (Clupea harengus membras L.) is one of the key species of the Baltic ecosystem. It is an important prey of many predatory fish, such as the Baltic cod and salmon, and it has a strong impact on the pelagic ecosystem as a predator of zooplankton and nektobenthos. Due to its wide salinity tolerance range, Baltic herring is able to live and reproduce in almost every part of the Baltic Sea despite of the varying environment (for information of the physical characteristics, visit the Baltic Sea Portal of the Finnish Environment Institute, Finnish Meteorological Institute, and Ministry of the Environment). Although the abundance and biomass of herring fluctuate from time to time even strongly, the stock has been large enough to be exploited commercially over decades. In Finland, the annual landings of herring represent over 80 % of the total fish catch by volume in the sea area and about 50 % of the economical value of the commercial fisheries.

The Archipelago Sea on the southwest coast of Finland is an island rich sea area characterised by complex coastline and shallow water body, mean depth being only ca 20 m. It has a large littoral area where vegetation mainly consists of macroalgae Fucus, Cladophora, Enteromorpha, Pilayella, Ectocarpus and vascular plants such as Potamogeton and Ranunculus, more rarely Zostera. Several rivers discharge fresh water to the area the largest being Aurajoki, Mynäjoki and Paimionjoki, which all have rather sheltered and productive estuaries.

Contacts and Research Group


Archipelago Research Institute | Saaristomeren tutkimuslaitos | University of Turku | Turun yliopisto | ©2013 Marjut Rajasilta & Päivi Laine