Fish Identification Photos: Leatherjack, Oligoplites saurus: The Leatherjack is characterized by its overall “jack-like” appearance, aerodynamic, very slender elongated body with a pointed snout, and a jaw that terminates slightly beyond the rear.

The Leatherjack is silver in color, with clear anal and dorsal fins and a yellow tail. It has short pectoral fins. The lateral line is slightly arched over the pectoral fin. There are no scutes.

This fish species can be easily confused with the Longjaw Leatherjack, Oligoplites altus (less aerodynamic with a longer jaw extending behind the eye), and the Shortjaw Leatherjack, Oligoplites refulgens (mouth ends before the pupil of the eye).

The Leatherjack is a pelagic fish species found in all Mexican waters south of Magdalena Bay, in the lower two-thirds of the Sea of Cortez, and along the coast of the mainland south to Guatemala. It is found in the first 150 feet of the water column over all types of terrain, and is reported to reach a length of 18 inches. It is a virtually an unknown species and of virtually no interest to anyone.

The Leatherjack is a small seldom seen member of the Carangidae or Jack family found in Mexican waters. The Jacks are found in all tropical and subtropical seas, with 140 individual species having been identified to date. They are voracious predators feeding primarily on small fishes. They frequently travel in large schools and roam considerable distances, normally following schools of smaller bait fish. They are generally silver in color, and exhibit a wide range in size from about 10 inches and 1 pound, to 6 feet and 90 pounds.

The Jacks are powerful midwater swimmers characterized by their streamlined, aerodynamic shape, with a latterly compressed body, slender tail base and deeply forked caudal fin. The posterior scales of the lateral line are modified into spiny, plate-like structures known as scutes (see juvenile Big Eye Trevally photo).

Many Jacks have elongated rays extending from their dorsal and anal fins (see juvenile African Pompano or Roosterfish photos).

Jacks spawn pelagically, releasing large numbers of tiny buoyant eggs that travel the globe, carried by currents. Most Jacks are esteemed as food fishes and are targeted by both commercial and sport fishermen. Jacks are found over rocky structure, along the edge of reefs and adjacent to large “drop-offs.”

Leatherjack, Oligoplites saurus: Shows up when one purchases a “scoop of bait.” Caught in the surf zone, in December 2003, 77-degree, 5 to 10-foot deep water, utilizing a net cast by a panguero bait salesmen. Size approximately 6 inches. This is a very rare, seldom seen, fish species without a name within the local fishing community. Description and photo courtesy of John Snow.