Londoners love their fish. And according to a new study, in the early 13th Century they suddenly started importing it from as far away as the Arctic near Norway. The research is in the journal Antiquity. About the year 1000, sea fishing increased significantly in northern Europe. To see how that increase influenced urban growth, researchers looked at 95 excavation sites in London. Which included about 3,000 bones from cod fish. Cod are decapitated before being dried for transport. So finding heads meant the fish were local. And the researchers found that as fish heads appear to decrease in the early 1200s, fish tails dramatically increased—a sign of importation, examination of the chemical isotopes in the tails matched those for fish in waters far to the north, probably off Norway close to the Arctic, more evidence of import.