Most people have eaten cod at some point in their lives, but up until recently, it was usually Atlantic cod. However, now only the Icelandic fishery remains in healthy condition for this type of fish. But because the demand for cod and its cousin the pollock fish continues to grow, the North Pacific fisheries have ramped up the production of similar species. Now nearly every fish stick, fast-food or breaded fish you will find in the U.S. is either Alaska pollock fish or Pacific cod.
Both fisheries are in excellent shape, so these fish are both economical and sustainable choices for seafood lovers. Pacific cod and Alaskan pollock are white, low-fat and mild fish. They typically come as skinless fillets and are commonly sold frozen. Both have a coarse flake when cooked and their bones make excellent stock.
Cooking Alaskan Pollock Fish
The difference is in texture: Pacific cod is nearly identical to its Atlantic cousins, although they are slightly less firm. Pollock fish, on the other hand, is soft.
Alaskan pollock makes fine fish sticks and fish cakes, is good steamed and is passable as fish and chips. Don't broil it, because if you make the slightest miscalculation you could wind up with dry fillets.
Another way to eat Alaskan pollock is as surimi, or imitation crab. Many of you have probably eaten it in a California roll at mid-range sushi bars; often the "crab" in this crab-and-avocado roll is actually Alaskan pollock, processed into surimi. It is supposed to taste like snow or king crab; it doesn't, but is okay for what it is.
Cooking Pacific Cod Fish
Pacific cod, on the other hand, is an excellent substitute for any recipe that calls for Atlantic cod. It is what you will get in most restaurants these days when you order cod.
Pacific cod is excellent baked, fried (especially batter-fried), sauteed and steamed. Pacific cod is also excellent in fish soups or chowders. Do not put Alaskan pollock in a fish soup unless you intend to puree it -- the fish will practically dissolve.
How to Buy and Store
Both fish freeze very well, and since both are from far-off waters, I would advise you to always buy it frozen, unless you can be assured that the fish has never been frozen before.
And please remember, do not eat either fish raw! They can sometimes harbor little parasitic worms that will pass on to you if you eat the fish raw -- that's why you will not see cod on a sushi menu. Although they don't die when the fish is frozen, the worms become harmless and are practically invisible once cooked. Reputable fish markets remove them when selling either fish fresh.