How to Identify Mackerel Scad

To identify Mackerel Scad (Decapterus macarellus), look at these key features.

Physical Characteristics

Body shape

torpedo

Coloration

Dorsal surface iridescent blue-green to dark blue, fading to silvery white on the flanks and belly. A distinct dark spot is often present on the upper operculum near the pectoral fin base. Fins are hyaline to dusky.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Elongate, fusiform body, slightly compressed., Adipose eyelid well developed, covering most of eye except for a central slit., Lateral line with a long anterior arch, becoming straight posteriorly. The straight part of the lateral line is fully covered with scutes., A detached finlet posterior to the dorsal and anal fins., Pectoral fin relatively short, not reaching the origin of the second dorsal fin.

Dorsal fin

Two dorsal fins; first dorsal fin with 8 spines, second dorsal fin with 1 spine and 29-34 soft rays, followed by a single detached finlet.

Tail fin

Deeply forked caudal fin.

Pectoral fin

Short, falcate pectoral fins, typically 1.2-1.4 times in head length, not reaching the origin of the second dorsal fin.

Distinctive fins

Anal fin with 2 detached spines anteriorly, followed by 1 spine and 25-28 soft rays, and a single detached finlet. Pelvic fins are small.

Identification Tips

1. 1

   Body Shape

   Look for the slender, torpedo-shaped body, characteristic of fast-swimming pelagic fish.

2. 2

   Finlets

   The presence of a single detached finlet behind both the dorsal and anal fins is a key identifying feature for the genus Decapterus.

3. 3

   Pectoral Fin Length

   Note the relatively short pectoral fin that does not extend to the origin of the second dorsal fin. This distinguishes it from some other Decapterus species.

4. 4

   Lateral Line Scutes

   Examine the lateral line; the straight posterior portion is fully covered with scutes, which are bony plates.

5. 5

   Opercular Spot

   A small, dark spot on the upper part of the operculum (gill cover) near the pectoral fin base is often present.

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