BIAS – Baltic International Acoustic Survey

Internationally coordinated hydroacoustic expeditions in the framework of the Baltic International Acoustic Survey (BIAS), an International Council for the Exploration of the Sea (ICES) survey programme, are carried out annually. The main purpose of the survey is to show the changes in fish stocks (indices) and geographical distribution of fish (mainly herring and sprat).

The expedition is conducted in October. The survey is an international collaboration between several Baltic Sea countries. Since 2019, the Swedish expeditions have been carried out with SLU's research vessel R/V Svea. Sampling is done with echo sounder, and pelagic trawls, all fish species in the catch are measured in length and biological samples, including age, are taken on the target species, herring and sprat.

The Baltic Sea countries meet in the Baltic International Fish Survey Working Group (WGBIFS) and the results from each country are compiled in a common database. WGBIFS also develops common guidelines and manuals. The results form the basis for the WGBFAS estimate of the total stocks of herring and sprat in the Baltic Sea.

Data are available from ICES's web : Acoustic trawl surveys.