Atlantic Cutlassfish, Trichiurus lepturus
The Atlantic Cutlassfish, Trichiurus lepturus, whose common Spanish name is sable del Atlántico, is a species in the Cutlassfish or Trichiuridae Family, known collectively as sables in Mexico. This fish is also known as the Largehead Hairtail and the Ribbonfish and is sold commercially in abundance as the Beltfish in the Asian markets of San Diego, California. Globally, there are only three species in the genus Trichiurus, two of which are found in Mexican waters, one in the Atlantic and one in the Pacific.
The Atlantic Cutlassfish have extremely elongated and strongly compressed ribbon-like bodies that taper to a point. They have a uniform silvery appearance being darker blue on their upper back and transitioning to silvery reflections ventrally with yellowish transparent fins. Their head has a long snout with large yellow eyes. They have a projecting lower jaw with a large mouth equipped with two or three pairs of large fangs and a series of sharp and compressed lateral teeth on both jaws. Their anus is closer to the tip of the snout than to the tip of the tail and their anal fin has 100 to 105 rays which are exceedingly small and usually embedded in the skin. Their dorsal fin is high and has a long base with three spines and 130 to 135 rays. Their pectoral fins are mid-sized. They do not have caudal or pelvic fins. Their lateral line begins at the upper margin of the gill cover, runs oblique to reach behind the tip of the pectoral fins, then continues straight across the ventral contour. They do not have scales.
The Atlantic Cutlassfish are a poorly studied benthopelagic and amphidromous species found in both marine and brackish environments over muddy bottoms of shallow coastal waters and in estuaries. They are found from the surface to depths of at least 2,000 feet and prefer water temperatures above 21oC (70oF). They reach a maximum length of 2.3 meters (7 feet 8 inches) and 5 kg (11 pounds) in weight. The current world angling record was caught in Brazilian waters in 1997 and weighed 3.7 kg (8.1 pounds). They are vertical migrators with adults being ambush predators that attack from below and feed near the surface on fish, shrimp, squid, and crustaceans during the daytime then retreat to the bottom at night. Juveniles form schools and feed at night on planktonic organisms near the surface then retreat to the bottom during the day. Males maintain exclusive home ranges while females move around more. They are known to migrate seasonally to wintering and spawning grounds. Reproduction is via dioecism with each female releasing up to 130,000 eggs per year which are fertilized externally by males. The eggs are scattered on the substrate and the subsequent pelagic larvae hatch in three to six days. They have a lifespan of up to fifteen years.
The Atlantic Cutlassfish are found in all Mexican waters of the Atlantic.
The Atlantic Cutlassfish is very similar to the Pacific Cutlassfish, Trichiurus nitens (smaller eyes; longer upper jaw; longer snout) and can also be confused with the Black Snake Mackerel, Nealotus tripes, the Snake Mackerel, Gempylus serpens, and the Striped Escolar, Diplospinus multistriatus, all of which have well-defined forked tails.
The majority of commercial catches of the Atlantic Cutlassfish are made in Asian waters of the Western Pacific using various types of nets, including trawls, with catches at the level of 1.5 tons per year placing it in sixth position in worldwide landing volume. Due to increased fishing pressure the body size of the average catch has been significantly reduced. They are marketed fresh, frozen, salted, and dried with fresh fish used for sashimi. They are also considered “excellent” when fried or grilled but are not popular in the United States. In the Gulf of Mexico they are used as live bait targeting large mackerel and wahoo and as a quality cut bait for bottom fishing.