The Marine Stewardship Council states that the cod fishery in the Eastern Baltic sea recovered well and issued it's MSC certificate to the Swedish cod fishery in 2011 for that region. (MSC 2011)
Data downloaded from EUROSTAT shows that Portugal, a main importer of codfish and -products, imported less and less from Norway (besides Iceland and UK the main supplier) (FAO 2006); dropping from around 20,000 tons (2001) to < 1,000 tons (2011) and more and more from Sweden; < 5,000 tons until 2003 versus > 30,000 in 2010 and 2011.
This trade data does not necessarily show the origin of a product but rather the country that is selling the fish. I wonder if either the Swedish cod fishery expanded in the past few (~ five) years; Portugal changed it's main supplier from Norway to Sweden for whatever reason; or Sweden buys cod from Norway and distributes it.
Depending on this the answer may not be so closely related to biology but I hope to get an idea here.