Atlantic Chub Mackerel, Scomber colias
The Atlantic Chub Mackerel, Scomber colias, whose common Spanish name is estornino del Atlántico, is one of the most common members of the Mackerel or Scombridae Family, known collectively as macarelas in Mexico. This fish is also known as the Atlantic Mackerel, the Chub Mackerel, and the Green Mackerel. Globally, there are only four species in the genus Scomber, two of which are found in Mexican waters, one in the Atlantic and one in the Pacific.
The Atlantic Chub Mackerels have elongated, rounded, fusiform, and tuna-like bodies that are designed aerodynamically for speed. They are silvery with greenish tinges and oblique lines zigzagging dorsally and have paler spots or markings with wavy lines ventrally. They have large black eyes with palatine teeth in single or double rows. Their anal fin is directly under the origin of the second dorsal fin and has 12 rays followed by 5 finlets. Their caudal fin is deeply forked with two small keels separated by one large keel at the slender tail base. They have two widely separated dorsal fins, the first having 8 to 10 spines and the second being small with 12 rays followed by 5 finlets; the distance between the two dorsal fins is equal to or less than the length of the first dorsal fin base. Their pectoral fins are short. They have 25 to 35 gill rakers. Their lateral line runs the entire length of the body and they are covered with small scales.
The Atlantic Chub Mackerels are a coastal schooling species found from the surface to depths up to 1,000 feet. They are epipelagic to mesopelagic over the continental slope. Schools are generally segregated by size and may include various bonitos, clupeids, and jacks. They are fast growing reaching a maximum 53 cm (21 inches) in length and 1.1 kg (2.4 pounds) in weight. They are reported to be vertical migrators that are found in the open ocean at night and on the bottom during the day. They also undergo seasonal migrations moving to cooler waters during the summer and returning during the winters. They are opportunistic predators feeding on small pelagic fish and invertebrates. In turn they are preyed upon by billfish, sharks, tunas, and other fish and marine mammals including sea lions and various sea birds and rely heavily on camouflage for protection. Reproduction is oviparous with spawning occurring in several small batches with each female releasing between 100,000 and 400,000 eggs per annum. Eggs and larvae are pelagic. They have a lifespan of up to thirteen years. The Atlantic Chub Mackerel is poorly studied and very little is known about their behavioral patterns.
In Mexican waters the Atlantic Chub Mackerels are found in all waters of the Atlantic with the exception of along the east coast of the Yucatán.
The Atlantic Chub Mackerel is very similar to, and can be easy confused with, the Pacific Chub Mackerel, Scomber japonicus (unmarked belly) and was only very recently separated as a different species. Otherwise it is an easy fish to identify.
The Atlantic Chub Mackerels are a heavily targeted commercial species in the eastern Atlantic including the Mediterranean Sea and caught with purse seines (often together with sardines), gill nets, traps, and via trolling, at a level of three million tons per annum. From a conservation perspective, they are very abundant in some locations, with noted populations declines in other locations, thus are currently considered of Least Concern globally but Near Threatened in certain parts of their range.
Atlantic Chub Mackerel, Scomber colias. Fish caught from coastal waters off Point Pleasant, New Jersey, August 2014. Length: 30 cm (12 inches). Catch, photo, and identification courtesy of Kenneth Tse, Toronto, Canada.