Mackerel are common fish found in oceans worldwide. Their streamlined bodies and rapid movements make them a common sight in coastal and offshore waters. Understanding their appearance assists in identification, whether in their natural habitat or a market. This article describes their general characteristics, highlights features distinguishing different species, and separates them from similar-looking fish.
General Mackerel Appearance
Mackerel species share common physical attributes that contribute to their fast-swimming capabilities. They possess a sleek, torpedo-shaped body, which tapers at both ends, allowing them to cut through water efficiently. Their coloration features an iridescent blue-green back that transitions to silvery-white sides and bellies. This countershading provides camouflage in the open ocean.
Mackerel have deeply forked tails, which are powerful propellers for speed. Behind their second dorsal and anal fins, they exhibit a series of small, individual finlets, a characteristic shared with other members of the Scombridae family, which includes tunas. Their bodies are covered in very small or imperceptible scales, contributing to their smooth appearance.
Key Features of Different Mackerel Species
While sharing a general body plan, various mackerel species display distinct markings and size differences.
Atlantic mackerel (Scomber scombrus) are identifiable by 20 to 30 wavy, dark bars that extend from their iridescent blue-green backs down to their silver sides. These bars are irregular and do not feature spots. Atlantic mackerel reach about 12 to 18 inches in length.
Spanish mackerel (Scomber maculatus) have a greenish back with silvery sides and belly, distinguished by numerous golden or olive-green oval spots scattered across their sides, both above and below the lateral line. The front of their first dorsal fin is dark or black. They are smaller than king mackerel, ranging from 14 to 18 inches.
King mackerel (Scomberomorus cavalla), the largest of these species, are characterized by a more uniform silvery body with a bluish-green back. Unlike Spanish mackerel, adult king mackerel lack prominent spots or markings, though juveniles may display faint bronze spots in irregular rows. They have a sharp, pointed snout and a lateral line that dips sharply below their second dorsal fin.
Pacific mackerel (Scomber japonicus) share similarities with Atlantic mackerel, exhibiting dark wavy lines on their backs. They have small, dusky spots on their lower sides, below the lateral line. Their head is dark blue, and the wavy lines number around 30.
Identifying Mackerel from Other Fish
Mackerel can be confused with other swift-swimming fish due to their similar streamlined shapes.
Bonito, also members of the Scombridae family, have distinct diagonal stripes or blotches on their backs and sides, which differ from the wavy lines or spots found on mackerel. Bonito also have a stouter body compared to the slender build of mackerel.
Small tuna species, such as skipjack or little tunny, can be differentiated from mackerel by their body shape and markings. Tuna possess a more robust, football-like body, while mackerel are more elongated. Small tuna have distinct dark stripes or patterns on their belly, which are absent in mackerel.
Bluefish (Pomatomus saltatrix) can be mistaken for mackerel, but they have several distinguishing features. Bluefish have a more compressed body laterally and a deeply forked tail, similar to mackerel. However, bluefish possess a single, dark lateral line and a prominent lower jaw with sharp teeth.