New Baltic Waters Lab in Sweden Aims to Revive Collapsed Baltic Sea Cod Population

The Baltic Waters fish research laboratory, located in Studsvik near Nyköping, Sweden, is on track to open in a few months to tackle the near-collapse of the Baltic Sea cod population. The facility includes 12 large pools for adult fish and 41 smaller ones, with cod designated as the first species to be reared and released. Baltic Waters, founded in 2020 to improve the Baltic Sea environment, has invested 150 million SEK into this project, which builds on cod research started in 2021 at an older Gotland facility now being phased out.

The lab’s strategy involves capturing wild cod to spawn in captivity, then releasing fertilized eggs back into the sea. Early trials in 2022 saw cod larvae released into the Tvären area; by 2023, cod were spotted there for the first time in 30 years, though their origin is uncertain. The mortality rate for cod larvae under one centimeter is over 99% due to predation, so the lab plans to rear larvae to about 50 days old, reaching 3-4 centimeters to improve survival rates before release. The goal is to release up to 100,000 cod annually.

Beyond cod, the laboratory will support other endangered Baltic fish like herring and plaice, fostering research opportunities. Located near a former nuclear research site, the facility benefits from existing water infrastructure, using 400 cubic meters of specially treated water daily.

According to Baltic Waters, this initiative is pivotal for ecological restoration in the Baltic Sea, combatting the severe decline of cod stocks and enhancing marine biodiversity.