However, it was not until the Viking era (1000 AC) that cod became an important economic commodity. At this time Norwegians used dried cod during their extensive travels to Iceland and Greenland. Cod are caught with hook and lines or simple longlines. Norwegian kings tried to benefit from the large cod resources by taxes and other regulations on the cod trade. By the end of the 14th century these trading licenses were granted to the Hanseatic League. The league was a loosely organized economic union between German and Baltic cities. A trade center for fur, timber and fish was established in the Bergen city. Dried and salted cod from Iceland and northern Norway was shipped to Bergen and further distributed to northern Europe. One hundred years later English merchants had established their own trade for cod from Iceland and Greenland without the consent of the Hanseatic League or from the Danish-Norwegian kings. The result became the first known cod wars, which ended with a Danish victory and monopoly on the cod trade. This monopoly remained until the eighteen century and forced the English, the French and the Basques to explore and exploit the vast cod resources along Newfoundland in the western Atlantic.
The cod recourses in both the western and eastern Atlantic seemed inexhaustible. However, over the centuries new gears developed and fishing effort increased. Besides hook lines, weirs and traps were used by an increasing number of dorymen off Newfoundland and set nets and purse seines were developed in Norway and Iceland. The first steam trawlers appeared in the late ninethteen century. After the 1st World War it became obvious that the compulsory stop in fishing during the war had augmented the cod stocks around Iceland. The same experience was obtained after the 2nd World War. No or little fishing during the war resulted in increased yields and stock sizes after the war. Sadly, there was no realistic attempt to impose any restrictions or management on the fisheries. Fishermen from any nation had an "open access" to all offshore resources. New bottom and pelagic trawls were developed to fish in previously inaccessible fishing grounds. New stern trawlers, power-blocks and electronic instruments became a survival necessity for any serious fisherman.
By the early 1960s the cod landings from the whole Atlantic fluctuated around 2.5 to 3 million tons per year with a peak in 1969 of 4 million tons. Mean yields from 1961 to 1970 were 1.4 million tons from the western Atlantic and 1.6 million tons from the eastern Atlantic cod stocks. The fate of the western cod stocks is well known. Increased fishing and decreasing spawning stock sizes resulted in overfishing and a biological collapse. The fishery for the major cod stocks in the western Atlantic was closed in 1992.
The development of the cod catches in the eastern Atlantic follow the same trend albeit with a slower pace. Landings amounted to 1.8 million ton in 1975 but declined to 0.8 million tons in 1992. A brief recovery was achieved in the mid 1990s by a combination of large incoming yearclasses and enforced management restrictions. However, by 2000 landings had declined to a low level of 0.8 million tonnes (see landings figure).
The decline in landings occurred simultaneously to large changes in the allocation of landings between nations. In the 1970s the debate of overfishing and fishing rights became fierce. Fishery scientists recommended severe management restrictions in order to arrest the increasing fishing effort and the dwindling number of mature and spawning cod in the seas. In 1975 Iceland unilaterally proclaimed an extended fishing zone of 50 nautical miles in order to protect "their" cod resources. English fishermen, who had traditionally caught between 20 to 35% of the total cod landings around Iceland, protested vividly. A second cod war started. Four years later all coastal nations had established exclusive fishing zones of 200 nautical miles in virtually all traditional fishing grounds around the world. A consequence was that the English fishermen were deprived of their fisheries around Iceland. Similarly Swedish fishermen had to find new fishing grounds in the Baltic to compensate for the loss of fishing in the North Sea.
Declining cod landings is a symptom of the state of the cod stocks in the sea. Scientists claim that the weight and numbers of adult cod in stock of the eastern Atlantic have decreased to alarmingly low levels (see stocks figure). The weight of spawning cod in North Sea and Skagerrak stock has decreased by 72% compared to the average from 1970 to 2000. The Kattegat spawning stock has decreased by 64% and the stock in Irish Sea by 63%. The record-low amount of spawners among cod stocks in the eastern Atlantic is predicted to jeopardize the future reproduction of these stocks. Of the 14 recognized cod stocks only one, the western Baltic stock, is considered to be within biological safe limits. Biological data for Rockall and Faroe Bank cod are too scarce to make biological assessments. The situation for other stocks in the eastern Atlantic calls for severe restrictions on the fisheries and in several cases a moratorium for further fishing.

The EU commission has recognized the significance of firm management action to restore these cod stocks.
A new Common Fishery Policy for the EU has been adopted. Important contents of this new policy are
- A multi-annual framework for the conservation of fish stocks
- A reduction of fishing capacity in response to the fishing effort limits
- A new regulatory framework for control and enforcement
- An establishment of Regional Advisory Councils for fisheries management

The progress of the new Common Fishery Policy for the EU can be found at http://www.europa.eu.int/comm/fisheries/reform/index_en.htm