25 June 2025/Kiel. Overfishing not only depletes fish stocks — it also alters the genetic blueprint of marine life. In the central Baltic Sea, cod (Gadus morhua) have not only become scarcer, but also significantly smaller than in the past. Researchers at the GEOMAR Helmholtz Centre for Ocean Research Kiel have now shown for the first time that Eastern Baltic cod grow markedly more slowly than they once did, and that this change is reflected in their genome. Intensive fishing pressure triggers genetic responses in overexploited stocks, with long-term implications for their future development. The findings are published today in the journal Science Advances.