Black Skipjack, Euthynnus lineatus
The Black Skipjack, Euthynnus lineatus, whose common Spanish name is barrilete negro, is one of the most common members of the Mackerel or Scombridae Family, which are known collectively as macarelas in Mexico. Globally, there are three species in the genus Euthynnus, all three being found in Mexican waters, one in the Atlantic and two in the Pacific.
The Black Skipjack have elongated fusiform tuna-like bodies. They are dark blue dorsally and transition to silver ventrally. They have a patch of five or six horizontal stripes on their back that extend from the origin of their dorsal fin. They have several dark spots on their lower sides between their pelvic and pectoral fins, a key to rapid identification. They have mid-sized black eyes, and slender conical teeth. Their anal fin has 11 to 12 rays and seven finlets. Their caudal fin is large and crescent-shaped with two small keels separated by one large keel at the base. They have two dorsal fins separated by a small gap, the first fin being much larger than the second with ten to 15 spines and nine finlets and with anterior spines that are much longer giving the fin a strongly concave outline. They have 33 to 39 gill rakers. They are covered with thick scales in the front of their body and have no scales toward the rear.
The Black Skipjacks are a pelagic species found in coastal waters at depths up to 40 meters (130 feet) with water temperatures in excess of 23oC (73oF). They reach a maximum length of 92 cm (36 inches) and 11.8 kg (26 pounds) in weight which is the current IGFA world record with this fish being caught off the Thetis Bank, Baja California Sur in 1991. They normally travel in small schools and at times form multi-species schools with Skipjack Tuna, Katsuwonus pelamis and Yellowfin Tuna, Thunnus albacares, being opportunistic predators. Very little is known about their behavioral patterns.
In Mexican waters the Black Skipjack are found in all waters of the Pacific with the exception that they are absent from the extreme northern portions of the Sea of Cortez.
The Black Skipjack can be confused with the Pacific Bonito, Sarda chiliensis (five to six oblique dark stripes on upper back with no spots), the Striped Bonito, Sarda orientalis (eight to 11 horizontal broken lines on back with no spots), and the Skipjack Tuna, Katsuwonus pelamis (four to six horizontal dark stripes on sides with no spots).
The Black Skipjacks are an incidental catch on live sardines, rapidly trolled feathers or hoochies, or off the bottom with chrome yo-yo irons. For their size they put up a horrific fight. Their meat is dark and they are viewed by locals as unedible. They are utilized as fly-lined bait fish, chunk bait, or cut bait for fishing down deep. They are caught at a fairly high level in commercial purse seines. From a conservation perspective they are currently classified as of Least Concern, being widely distributed and not targeted by either commercial fishermen or recreational anglers.
Black Skipjack, Euthynnus lineatus. Fish caught from coastal waters off Point Palmilla, Baja California Sur, April 2015. Length: 90 cm (35 inches).