Bacalhau is the Portuguese word for salted and dried codfish. A tradition in the Portuguese cuisine. Fresh codfish in theory should not be called bacalhau, although many people tend to just incorrectly call it the same. Bacalhau is basically a salted and dried fish from the gadus family. The raw material used to process bacalhau can be from fresh fish or frozen fish.
In trade we view several marketing techniques especially from Norwegian and Icelandic producers who try to pass on the idea that bacalhau made from fresh fish is of better quality than the one made from frozen. Sincerely I have a divided opinion on this matter due to several factors which I will clearly try to explain.
When bacalhau is processed from fresh codfish, the fishing is normally done with small coastal vessels, Norway and especially Iceland have good conditions for this type of operation. However the time taken to arrive at the bacalhau processing plants can determine significantly the quality of the bacalhau. Small fishing vessels in general do not have refrigerated storage, therefore during a day out at sea it's important to avoid a large time gap between the time the fish is captured and the time it arrives and is processed. A fish should not attain a "rigor mortis" state.

Producing bacalhau from frozen fish, basically has two origins, frozen in land and frozen at sea. In my opinion, if the vessel is properly equipped, frozen at sea may be he best option. The codfish is quickly processed in mini on board plants and frozen, which maintains a good level of freshness to the product, very far from a "rigor mortis" state.
Frozen on land is a similar situation to the one described for bacalhau produced from fresh fish, instead of being processed it's frozen. The quality of the product depends on the fishing technique used and the time it spent before being frozen.
Fishing season starts with new quotas in January, season A ends around mid April. In September fishing re-starts ending as soon as quotas have been fulfilled. So it's normal and logic that both frozen and fresh codfish is used in processing bacalhau.
In MHO if the vessel works well and everything goes smoothly either fresh or frozen may be good options in the bacalhau processing industry. Using fresh or frozen sincerely can't really say which one has impact in the flavor or quality of final product.
However fresh fish is cheaper than frozen, but also have bigger breakage in production. Some say fish is whiter if made from frozen raw material. Unfortunately too many variables involved in processing bacalhau, brands may be an assurance of quality, personally I do not valuate Norwegian origin over others. In fact, currently Russian vessels are better equipped for cod fishing and freezing than the Norwegian fleet.