Ocean warming drives new fish species into Danish waters, North Sea cod stock shifts north
Henrik Carl, head of the Danish fish atlas project, notes that warming is making sardines, anchovies and other new species increasingly common in waters around Denmark, with golden grey mullet and spotted scat also arriving; meanwhile, cod, which cannot tolerate high temperatures, has shown signs of migrating to more northerly waters in the North Sea.
The fish composition in waters around Denmark is changing. According to the Danish fisheries newspaper Fiskeritidende on 13 October 2026, sardines, anchovies and flounder have already become increasingly common in waters around Denmark, and species such as golden grey mullet and spotted scat are now arriving as well.
This change is attributed to ocean warming caused by climate change, which has affected Danish waters too. Henrik Carl, head of the "Fish Atlas" (Fiskeatlas) project at the Natural History Museum of Denmark, described the situation to Folkebladet Lemvig. He has led the project for 20 years, and its work is to record Denmark's fish species and their distribution.
"What surprises me most is how fast it is going. We have been doing the fish atlas for 20 years, and a great deal has happened during that time," Carl told the outlet.
Ocean warming not only attracts new species but also prompts some known fish to move to colder waters. Cod is one example; it cannot tolerate continuously rising water temperatures. There are already signs that the cod stock in the North Sea is migrating to more northerly waters.
However, Carl did not give a figure for what proportion of the cod decline is caused by ocean warming.
"But I cannot see any bright future for cod. That is very sad, because it used to be the most important predatory fish in our ecosystem," he told Folkebladet Lemvig.