Snake Mackerel, Gempylus serpens
The Snake Mackerel, Gempylus serpens, whose common Spanish name is escolar de canal, is a species in the Snake Mackerel or Gempylidae Family, known collectively as escolares in Mexico. Globally, the Gempylidae Family includes the snake mackerels, oilfish, escolares, and cutlassfish with twenty-four members placed in sixteen genera. There is only one species in the Gempylus genus, the species described herein, which is found in all Mexican waters of the Atlantic and the Pacific.
The Snake Mackerels have very elongated, slender, and compressed bodies that taper toward the tail and have a mid-length depth that is 7.0 to 7.4% of standard length. They are dark brown to blackish in color with silvery reflections and gray-brown fins with dark margins. Their head is deep and large with a pointed snout and large eyes. Their mouth has a pointed projecting lower jaw equipped with large conical teeth spaced apart with a pair of fangs at the front of their top jaw. They have an anal fin with two free spines followed by one spine and 10 to 12 rays and 6 or 7 finlets. Their caudal fin is deeply forked. They have two dorsal fins: the first is long and low with 26 to 32 spines and the second is short and followed by 5 to 7 finlets. Their pelvic fins are minute. They have two lateral lines, one mid-body and the other under their dorsal fin. They are covered with small scales but smooth to the touch.
The Snake Mackerels are an oceanic species found from the surface to mid-water at depths up to 3,280 feet. They reach a maximum 1.42 meters (4 feet 7 inches) in length and 3.0 kg (6.6 pounds) in weight. They are a solitary species and make vertical migrations toward the surface at night to feed. They consume cephalopods, crustaceans, and fish. In turn they are preyed upon by marlin and tuna. Reproduction is oviparous with each female releasing between 300,000 and 1 million eggs. Eggs and larvae are pelagic. As fish mature they move to deeper waters and the cone cells in their eyes change to rod cells. They are a poorly studied species and very little is known about their behavioral patterns.
In Mexican waters the Snake Mackerels are found in all waters of the Atlantic; in the Pacific they are found in all waters with the exception of the Sea of Cortez.
The Snake Mackerel can be confused with a series of fish from the Atlantic including the Atlantic Cutlassfish, Trichiurus lepturus, the Black Gemfish, Nesiarchus nasutus, the Black Snake Mackerel, Nealotus tripes, the Oilfish, Ruvettus pretiosus, the Roudi Escolar, Promethichthys prometheus, and the Striped Escolar, Diplospinus multistriatus as well as a series of fish from the Pacific including the Pacific Cutlassfish, Trichiurus nitens and the Oilfish, Ruvettus pretiosus, however, all these fish have two or less finlets following their anal and dorsal fins. In addition, the Cutlassfish do not have forked tails.
The Snake Mackerels are not an important commercial species. They are caught as a by-catch in the longline tuna and swordfish fisheries and marketed frozen or in sausages and fish cakes. In a limited number of cultures they are considered a quality food fish. From a conservation perspective they are classified as of Least Concern.
Snake Mackerel, Gempylus serpens. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, February 2011. Length: 33 cm (12 inches).