The catastrophic decline of North Sea cod as the result of over fishing has had an impact on all our menus, from the poshest restaurants to the corner chippie: the fish left are few and small, compared with those of less than a century ago. Cod more than a metre in length are rare these days, whereas archaeological remains show that fish several times that size were common.
A new study shows that cod were exploited in the Middle Ages from many, often distant, fishing grounds, with an international trade in dried stockfish. Some fish eaten in a Yorkshire village may have been some from off the coast of Sweden, while merchants in what is now northern Germany ate cod from Arctic Norway.
Co-operation by archaeologists and scientists from Britain, France, Belgium, Germany, Scandinavia and the Baltic states has allowed medieval cod bones recovered from sites as far apart as Poland and Orkney to be analysed for their stable-isotope content. Variation in the isotopes of carbon and nitrogen is regional, “making it possible to identify bones from cod caught in distant waters”, James Barrett and colleagues report in the Journal of Archaeological Science. Their work suggests that this long-distance fish trade had already begun by late Anglo-Saxon times, at the end of the first millennium AD.