Jack Mackerel, Trachurus symmetricus
The Jack Mackerel, Trachurus symmetricus, whose common Spanish name is charrito chicharo, and whose local name is chilly willy or chee willie, is a member of the Jack or Carangidae Family, known collectively as jureles and pámpanos in Mexico. There are twenty global members of the genus Trachinotus, seven of which are found in Mexican waters, three in the Atlantic and four in the Pacific.
The Jack Mackerels have “mackerel-like” elongated slender modestly compressed bodies with a depth that is 17 to 21% of standard length. They are metallic blue to olive green in color and their lower two-thirds are paler ranging from white to silver. They have a black spot on the upper edge of their gill cover. Their head is pointed and features large eyes with fatty eyelids. Their dorsal fin has eight spines followed by 31 to 33 rays. Their anal and second dorsal fins have long bases and are similar in appearance, however, the anal fin is slightly shorter. They have long pectoral fins and no isolated finlets. Their caudal fin has a wide and deep “V” shape. A key to identification is their lateral line, which is arched in the middle and has well developed scutes on both curved and straight parts. Their body is covered with scales.
The Jack Mackerels are a coastal schooling pelagic species found from the surface in the surf zone to depths of 1,320 feet. They reach a maximum of length of 81 cm (32 inches). They are a poorly studies species and very little is known about their behavioral patterns.
In Mexican waters the Jack Mackerels have a limited range in waters of the Pacific being found along the entire west coast of Baja and from Santa Rosalia southward along the central and southeast coasts of the Baja.
The Jack Mackerel can be very easily confused with the three Mackerel Scads of the Decapterus Genus found in Los Cabos waters: the Amberstripe Scad, Decapterus muroadsi, the Mackerel Scad, Decapterus macraellus, and the Shortfin Scad, Decapterus macrosoma (all of which have less prominent scutes on their lateral line). All four are known locally as chihuil (chee-willie or chilly willy).
I catch Jack Mackerel at certain times of year out of rather deep water on cut squid or yo-yo iron with larger individuals being a strong foe on light tackle. I have also caught them with hand lines and small treble hooks during predawn hours off the surface well out at sea at a rate of two dozen per hour chummed in with cut Skipjack Bonito; however, the bite will stop with daylight. They readily survive bait tanks, thus are a favorite of local Pangueros, who use them as a slow-trolled live bait targeting dorado, sailfish, and the elusive wahoo during the fall season. They are not normally retained for table fare.
Jack Mackerel, Trachurus symmetricus. Underwater photo taken in coastal waters off La Jolla, CA, September 2017. Length: 23 cm (9.0 inches). Photo courtesy of Bob Hillis, Ivins, UT.
Jack Mackerel, Trachurus symmetricus. Fish caught from coastal waters off Santa Cruz, California, May 2016. Length: 25 cm (10 inches). Catch, photo and identification courtesy of Andrew Hansen, Santa Cruz, CA.