Bacalao is made of Norwegian klippfish and is not really a Norwegian traditional dish in the true sense, but originating from Spain and Portugal. But Norwegian klippfish exporters and sailors learned the to love the dish in the late nineteenth and early twentieth century and took the spice that was needed to make bacalao home to the north-western coast of Norway where it eventually became part of the culinary tradition. My x-mother-in-law was from a klippfish exporter family and she made a fantastic bacalao.
Klippfish is a far more refined product than dried fish which is also produced in large quantities in Norway , and should not be confused with this. Dried fish is dried out in the wind, and is not added salt. klippfish is dried indoors now and is always added large amounts of salt.
In Norwegian culture klippfish has an exotic touch. Unlike dried fish, klippfish is a product that was introduced to Norway from abroad. Probably it is the case that Spanish fishermen "invented" klippfish as early as around 1500 as they fished off Newfoundland and needed a preservation method. The North-West coast of Norway on the other hand was ideal for producing klippfish so most klippfish has been produced there for ages now and as you see from the picture it was dried on the rocks along the coast before indoor drying became the standard.
It has been a few comments on the use of the word stockfish for the product in this dish on this post on Facebook and since both Google translator and Wikipedia used the words dried fish and stockfish quite confusing I had to go to slowfish.no to get the translation right and the correct word is “klippfish” so this has now been corrected – Ted