Mackerel eat copepod larvae, copepod eggs, adult copepod, small fish larvae, euphausiid shrimps, planktonic animals and pelagic Crustacea. Residents of many countries enjoy eating mackerel, but it is not a popular fish choice in the United States because it has a very strong flavor, especially when raw.
Mackerel are greedy fish when it comes to eating, and they will go for almost any bait that is used to lure them. They especially like bait like pieces of clam or small strips of mackerel belly skin. They also favor live bait because it moves. Mackerel have been known to eat their own species' eggs as well.
Mackerel eat through two different methods. The first involves eating the prey after seeing it. The second involves using the mackerel's gill rakers to gather prey. When this occurs, the prey goes straight to the mackerel's mouth to be swallowed.
The fish are not thought to eat much during the winter because fisherman have noticed for centuries that the fish are quite fat during the fall, but in the early spring they are gaunt. This is thought to be in part due to the mackerel's long migration. The mackerel is sensitive to water temperature changes and will migrate long distances each winter to find warmer waters.