THE SPECIES OF COD
Cod is the king of whitefish, a species over which wars have been fought and trading fortunes made for hundreds of years. Today, cod is as popular as ever. Salt cod remains a staple food in Portugal, Spain, Italy and Brazil, while fresh and frozen cod, is widely consumed throughout North America, Europe and Japan, where its flaky white flesh has an almost universal appeal.
Found throughout the North Pacific and North Atlantic, cod is the world’s second largest whitefish resource after Alaska pollock. In most years, cod landings average between 1.5 million and 2 million metric tons (compared to 3 to 4 million metric tons for Alaska pollock). The cod resource is far larger in the Atlantic, where catches are normally about four times higher than in the Pacific. If the quality is equal, for all practical purposes, the two species are identical from a culinary standpoint.
The Alaska fishery is by far the most important cod fishery in the Pacific. Alaska fishermen catch between 250,000 and 300,000 tons of cod each year, about 60% of which is caught by freezer longliners and the rest by trawlers and pot boats. Factory trawlers produce FAS (frozen-at-sea) fillets, while shore plants in Alaska produce frozen fillets.
Off the West Coast, where Pacific cod is often called “true cod” or “gray cod” or “P-cod,” less than 1,000 tons of cod are caught each year as a bycatch in the trawl fisheries for rockfish and flatfish.
Black cod, which also goes under the names butterfish and sablefish, is a rich white-flesh fish with a moist, succulent texture. Its habitat stretches from the Bering Sea to California, and the Monterey Bay Aquarium Seafood Watch ranks black cod from Alaska as a “Best Choice.”
Even though this fish is marketed as “black cod,” it is not a true cod. Black cod has one of the highest levels of healthy Omega-3 fatty acids, which give them their silky and rich texture and flavor. While almost all the West Coast cod catch is marketed as fresh fillets, the Alaska catch is almost always frozen, although some fresh cod fillets are air freighted from Alaska to markets in the "Lower 48", where cod is a favorite fish.
There can be significant quality differences with cod, depending upon the time of the year the fish is caught. In the spring, for example, when cod are feeding heavily on small, oily fish like capelin, their flesh is noticeably softer. Quality is also a function of how the fish was handled. As a rule, the best fresh cod comes from short trips on boats that gut, bleed and ice their fish. The best frozen cod is normally FAS (Frozen At Sea) fillets. Be aware, though, that how a fish was caught and processed is not a guarantee of quality.
Large quantities of imported frozen cod fillets are sold in the U.S.
Even today, the market for salted cod, which is called bacalao, is very large in countries like Brazil, Portugal, Spain and Italy. Traditionally, cod was the fish of choice for fish blocks that are used to make fish sticks and fish sandwiches at fast-food restaurants. As cod prices have increased, however, Alaska pollock has replaced cod in these applications.
A good read: COD by Mark Kurlandsky. The book reveals the importance of cod in history that changed the world.