How to Identify Atlantic Chub Mackerel

To identify Atlantic Chub Mackerel (Scomber colias), look at these key features.

Physical Characteristics

Body shape

torpedo

Coloration

Dorsal side is iridescent blue-green with a pattern of dark, wavy, oblique lines extending from the head to the caudal peduncle. The flanks are silvery with a series of dark spots or blotches, particularly below the lateral line. Ventral side is silvery-white.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Two widely separated dorsal fins, Five dorsal finlets and five anal finlets, Small, cycloid scales covering the entire body, Large eyes, Absence of a swim bladder (or greatly reduced), A series of dark spots or blotches on the lower flanks, often below the lateral line

Dorsal fin

Two dorsal fins; the first with 9-10 spines, the second with 1 spine and 11-12 soft rays, followed by 5 finlets. The first dorsal fin originates anterior to the pectoral fin base.

Tail fin

Deeply forked caudal fin, characteristic of fast-swimming pelagic fish.

Pectoral fin

Short, located high on the body.

Distinctive fins

Five small finlets posterior to both the second dorsal and anal fins.

Identification Tips

1. 1

   Dorsal Coloration

   Iridescent blue-green back with distinct, wavy, dark lines. This distinguishes it from Atlantic Mackerel (Scomber scombrus) which has more pronounced, unbroken wavy lines.

2. 2

   Flank Spots

   Presence of dark spots or blotches on the lower flanks, below the lateral line. This is a key differentiator from Atlantic Mackerel, which lacks these spots.

3. 3

   First Dorsal Fin Origin

   The origin of the first dorsal fin is anterior to the pectoral fin base, a subtle but consistent morphological trait.

4. 4

   Number of Finlets

   Consistently five dorsal and five anal finlets, a characteristic of the genus Scomber.

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