Why does the mixing of North Sea waters support abundant fish populations?

The constant mixing of waters in the North Sea’s shallow basin is essential for its high biological productivity. This process ensures a rich supply of nutrient salts, which are vital for the growth of lower marine organisms that form the foundation of the sea’s food chain.1

This nutrient-rich environment fosters an abundance of plant and animal plankton, which in turn supports a diverse and plentiful population of commercially valuable fish, such as cod, haddock, and herring.1