Atlantic Cod from Iceland (the country!), the Barents Sea or the Norwegian sea
These are currently (Jan, 2016) the only places where stocks of cod are thought to be high enough for sustainable finishing. Cod likes cold water and our recent mild winters mean that stocks aren’t high enough in Cornwall yet – although they are working to improve this.
Cod fished from almost everywhere else. Decades of overfishing have resulted in dramatic cod population declines in the Atlantic. Pacific cod from Japan and Russia is said to be just as bad, but opinions on that are currently divided.