Trålundersökning av fisk i Östersjön: Baltic International Trawl Survey Q1 2025

Baltic International Trawl Survey (BITS) is an internationally coordinated bottom trawl expedition in the Baltic Sea with cod as the primary target species. The expedition is carried out twice a year, in quarters 1 and 4 and covers the Baltic Sea proper. Seven countries are included in the program. The report covers the expedition carried out with R/V Svea 20 February-4 March 2024. Sweden was assigned 51 stations. A total of 59 stations were trawled with TV3L bottom trawl in accordance with the BITS manual (ICES, 2017). Of these 59 stations, two stations were low in oxygene (which were not trawled due to the oxygen concentration near the bottom was close to 0), five hauls were declared invalid and one additional haul (for biological samples, only). The expedition covered parts of areas SD 24, 25, 27 and 28 this year. Acoustic data was collected continuously throughout the expedition.The total catch of 30 035 kg was dominated by herring, sprat, cod and flounder. During this survey, a total of 22 different fish species were caught. Biological sampling was carried out on cod and flounder. Biological sampling involves taking samples from each individual, such as DNA samples, ear stones (otoliths), liver samples, etc.Hydrographic parameters such as salinity, temperature and oxygen concentration were observed and measured at all trawl stations. In this report, the oxygen concentration is shown about 1 meter above the bottom.