Mackerel, an important ocean food fish related to the tuna. The common Atlantic mackerel is abundant along the north Atlantic coasts of North America and Europe. It is a slender fish, 12 to 22 inches (30 to 56 cm) long, with a deeply forked tail and two widely spaced back fins. The fish is bluish-green above, silvery beneath. Its back is marked with wavy, dark-blue bars. (The term “mackerel sky” refers to striped clouds of similar design.) An Atlantic mackerel weighs from one to four pounds (0.45 to 1.8 kg) and has slightly oily flesh.Mackerel swim near the water's surface in dense schools.
The similar Pacific mackerel is caught from California northward to Alaska. The Spanish mackerel, which weighs from 6 to 10 pounds (2.7 to 4.5 kg), is common throughout the world.
Mackerel swim near the surface in dense schools that are sometimes 20 miles (32 km) long. They feed chiefly on shellfish larvae, worms, fish eggs, and small fish, and are themselves eaten by whales, sharks, porpoises, tuna, and sea birds. In the spring, mackerel migrate close to shore to spawn. The female lays from 200,000 to 400,000 eggs. Each egg contains a tiny drop of oil that causes it to float. The eggs hatch in four to six days. The young fish grow rapidly, reaching an average length of about two inches (5 cm) in two months. In the fall, the mackerel move out to sea into deeper water.
Mackerel are caught with trap nets, gill nets, and hand lines from spring to early fall. They are marketed fresh, frozen, smoked, salted, or canned. The United States, Canada, Great Britain, and Norway have important mackerel fisheries. The North American catch is chiefly Pacific mackerel.
The Atlantic mackerel is Scomber scombrus; Pacific, S. japonicus; Spanish, Scomberomorus maculatus. All belong to the family Scombridae.