After research on the immediate decline of cod it is found that the catastrophic decline of North Sea cod as the result of over fishing has been dated a century ago. The study shows that cod fish were exploited in the Middle Ages from many, often distant, fishing grounds, with an international trade in dried stockfish. Archeologists 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.
James Barrett and colleagues in their report in the Journal of Archaeological Science states that the variation in the isotopes of carbon and nitrogen is regional which makes it possible to identify bones from cod caught in distant waters. It suggests that the long-distant fish trade had already begun by late Anglo-Saxon times. The report also revealed that the consumption of marine fish such as cod increases in 1000 AD in parts of Northern and Western Europe.
According to the study collected bones from archeological sites shows that there were long-distance fish traded which means that the cod fish was over fished during medieval period which led to its dwindling numbers. It is observed that in medieval times the cod fish comes far places like Kattegat, western Baltic Sea, eastern end of the Kiel Canal, Arctic Norway and the likes.
This suggests that cod fishing had been popular in olden times also and was much exploited. It also suggests that the origins and growth of commercial fishing in northern Europe has strong historical record.
