The two varieties of Pollock, Alaskan and Atlantic, are similar enough so that either may be used in most recipes. Although there is a difference in texture- Alaskan Pollock tends to be less firm than Atlantic. This only really matters if grilling, in which case you may want to take advantage of the firmer, slightly oilier texture of the Atlantic because it holds up well to high heat.
Alaskan and Atlantic Pollock are sold almost exclusively as fillets, though you may occasionally find steaks or the whole fish in your market. Prepare fillets by broiling or bake in the oven with a sauce to help the fish retain moisture. Or, try another gentle cooking method like steaming the fillets and serving atop a bed of vegetables or rice.
Pollock is a very mild fish (similar to cod) that can be overwhelmed by overly acidic or strong flavors. Experiment with milder seasonings at first and gradually add more if you still feel you want to boost flavor.
Pollock is cooked when it is no longer translucent and the flesh begins to flake.