I newly published study shows that the areas in which large cod and flounder in the Baltic Sea live together have decreased substantially in the last 40 years. Large cod can eat flounder and can potentially control the flounder abundance in the Baltic. The disappearance of large cod and the decrease in overlap with flounder could thus be one of the causes of the increase in the flounder population in the Baltic.
We also show that the areas in which small cod and flounder live together have increased substantially at the same time. Small cod and flounder both eat organisms that live on the seafloor and our analyses suggest that an increased competition for food due to a stronger overlap with flounder may be one of the factors affecting the state of Baltic cod.
Read the Open Access paper “Long-term changes in spatial overlap between interacting cod and flounder in the Baltic Sea” on Hydrobiologia.