Mackerel Scad, Decapterus macarellus
Mackerel Scad, Decapterus macarellus. Fish caught from within the Kapa’a Canal, Kauai, Hawaii, July 2023. Length: 14.0 cm (5.5 inches). Catch, photograph and identification courtesy of Chris Moore, Peoria, Arizona.
Mackerel Scad, Decapterus macarellus. Fish caught from coastal waters off Deerfield Beach, Florida, December 2020. Length: 28 cm (11 inches). Catch, photograph and identification courtesy of Ben Cantrell, San Diego, California.
Mackerel Scad, Decapterus macarellus. Fish caught from coastal waters off Point Palmilla, Baja California Sur, November 2015. Length: 32 cm (13 inches). Fish identification courtesy of H.J. Walker, Jr., Scripps Institution of Oceanography, La Jolla, California.
Mackerel Scad, Decapterus macarellus. Fish set up and ready to rumble.
The Mackerel Scad, Decapterus macarellus, is a member of the Jack or Carangidae Family, that is known in Mexico as macarela caballa. There are twelve global members of the genus Decapteurs, of which five are found in Mexican waters, two in the Atlantic, two in the Pacific, and one in both the Atlantic and Pacific Oceans.
The Mackerel Scad has a “mackerel-like” elongated slender cylindrical body with a depth that is 16% to 20% of standard length. The top and rear ends of their upper jaw are straight and the lower corner is angular. They are bluish-green dorsally and silvery ventrally. They have a small black blotch on the upper edge margin of their gill cover. Their anal fin has two standalone spines followed by 1 spine and 27 to 31 rays; their caudal fin has a slender base and is deeply forked; their first dorsal fin has 8 spines; their second dorsal fin has 1 spine and 31 to 37 rays; and, their pectoral fins are short. They have 10 to 13 gill rakers on the upper arch and 34 to 41 gill rakers on the lower arch. The anal fin base is relatively short and their second dorsal fin base is long. Their lateral line has a long low arch anteriorly with 23 to 32 scutes. Keys to identification are the 110 to 138 scales and the scales on top of their head that extend forward to the anterior margin of the pupil.
The Mackerel Scad are a pelagic species found mainly in oceanic waters at depths up to 400 m (1,310 feet). They reach a maximum of 46 cm (18 inches) in length. As of January 1, 2024, the International Game Fish Association world record stood at 0.55 kg (1 lb 3 oz) with the fish caught in coastal waters off Japan in August 2005. The Mackerel Scad is poorly studied is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.
The Mackerel Scad is a resident of Mexican waters of both the Atlantic and Pacific Oceans. In the Atlantic they are found in all waters including the Gulf of Mexico and the east coast of the Yucatán Peninsula in the Caribbean. In the Pacific they are limited to the southern fourth of the Sea of Cortez.
The Mackerel Scad can be easily confused with the Amberstripe Scad, Decapterus muroadsi (scales on head but less than 20 scales on straight portion of lateral line), the Shortfin Scad, Decapterus macrosoma (no scales on head), and the Jack Mackerel, Trachurus symmetricus (numerous strong scutes; arched lateral line). All four are known as Chi-willie by local Mexican fishermen. Note: There are three Scads of the Decapterus genus residing in Mexican waters of the tropical Eastern Pacific that are exceedingly difficult to separate: the Amberstripe Scad, Decapterus muroadsi, the Mackerel Scad, Decapterus macarellus, and the Shortfin Scad, Decapterus macrosoma. Two of the three (the Mackerel Scad and the Shortfin Scad) can only be identified conclusively via microscopic examination to determine the shape of their jaw bone and the scale count within the flat section of their lateral line. The Amberstripe Scad, it is normally bigger than the other two and the yellow upper caudal fin lobe are keys.
From a conservation perspective the Mackerel Scad is currently considered to be of Least Concern with stable, widely distributed populations. They are caught by commercial fishermen utilizing gillnets, haul seines, purse seines, bottom trawls, and hook-and-line. That are utilized by some cultures as subsistence food. The Mackerel Scads show up in the San José River basin in the greater Los Cabos area of Baja California Sur during the cold water periods between December and February when they can be caught in abundance on Sabiki type rigs out of 300-foot water. They survive bait tanks well and are utilized as live fly-lined or troll bait to target the larger big game fish such as Dorado, Striped Marlin, and Yellowfin Tuna. If retained past the daily outings in the Los Cabos area, they are frozen and used later as dead fly-lined or trolled bait and cut bait for bottom fishing.