Cod in the Baltic Sea (IMAGE) Swedish Research Council Caption A new investigation put in evidence the key role of cod as regulator of the whole Baltic Sea ecosystem. The study shows that when the cod population in the central Baltic increases, it spreads into larger areas and spills over into adjacent marginal systems where it usually does not occur, as for example the Gulf of Riga. Credit Roger Jansson Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.