The organization Balticwaters2030 runs the ReCod project.
Wild-caught cod have reproduced in the research station's large water tanks.
Their larvae are now placed in three locations in the Baltic Sea.
The hope is that the larvae will be able to develop into fry and then survive to become adult fish.
In this way, the cod stock can get a fresh start, which can then lead to a better ecosystem.
Start the clip above to see images from the release of caterpillars.