From The Food Encyclopedia by Jacques Rolland and Carol Sherman
Popular saltwater fish, once the staple of the North Atlantic, doubly valuable because it could be salted and dried, allowing it to be caught far offshore and kept for months before using. Cape Cod was named after it, and a wooden cod hangs above the entry to the Massachusetts State House in Boston. No food was more important, and it was so plentiful that the air bladders of the fish (called cod sounds) were stewed in milk as a popular breakfast item. Now, however, the true Atlantic cod, Gadus morhua, while not an endangered species, is what the experts call a "depleted fishery" and can no longer be profitably caught and sold for widespread distribution. Today, Atlantic cod comes mainly from Icelandic waters, which that nation began strictly managing in the 1950s. Haddock, Melanogrammus merluccius, often sold as cod, is not much more plentiful. Hake, Merluccius virens, and whiting, Merlangus merlangus, are abundant on both coasts and good substitutes for cod in most recipes. See also salt cod.
