Bleed mackerel with a throat cut and then gut and ice them immediately. Gutting mackerel as soon as possible is critical when they are feeding heavily in the summer months. If immediate gutting is impossible, pack mackerel in ice quickly to preserve their quality and ensure the safety of those who will eat them. Handle them gently and as little as possible to avoid bruising and further softening of the flesh. Mackerel are generally used as fillets or steaks, but some recipes call for whole fish.
Atlantic mackerel have soft, dark flesh and a strong, characteristic flavor.
Spanish mackerel have a fairly light color and a milder flavor. They are generally considered to taste better than other mackerel. King mackerel have a strong flavor and are usually marinated before cooking. If properly handled, mackerel will remain in good condition for several days. To freeze them, glaze them or wrap them well to prevent rancidity.