Mackerel, like trout, must be kept absolutely cold until cooked. While it is unrealistic to expect anyone to carry an ice cooler on the trout stream, it is no problem to keep a cooler on a boat, dock, or bridge. The first step in preparing a memorable mackerel feed is to take the fish from the hook and place it on ice.
Clean the fish like this: remove the head and place the mackerel on its belly. Make a cut down through the back, from end to end along either side of the backbone, being careful not to cut through the belly. Open the fish and remove the insides. The end result will be a flat mackerel. Ocean fish were once prepared for drying in this manner.
Don’t fry mackerel. They are too oily and you will not appreciate their delicate flavor. Instead, broil the fish in the oven or better yet, outdoors on the grill. You can broil mackerel as is, but the author likes to make a marinade. Italian salad dressing is a quick and easy marinade but almost anything will work; use your imagination. You can also squeeze lemon juice over each mackerel and coat with freshly ground black pepper.
Watch the mackerel closely as you cook them. Don’t let them dry out. The oil will drip into the fire, fanning the flames while at the same time basting the fish in flavorful smoke. Keep checking for doneness by separating the flesh with a fork. When it is pure white, with no trace of red, the mackerel is done. The final product is an epicurean delight, fit for royalty.