Pacific Chub Mackerel, Scomber japonicus
The Pacific Chub Mackerel, Scomber japonicus, whose common Spanish name is macarela estornino, 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 Chub Mackerel, the Green Mackerel, and the Pacific 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 Pacific Chub Mackerels have elongated rounded fusiform tuna-like bodies that are designed aerodynamically for speed. They are silvery with greenish tinges and have blackish oblique stripes that zigzag and undulate on their upper back. They have large black eyes with palatine teeth in single and double rows. Their anal fin is small and originates opposite the second dorsal fin; it has one spine and 12 to 14 rays followed by 5 finlets. Their caudal fin is deeply forked with two small keels separated by one large keel at the slender base. They have two widely separated dorsal fins, the first having 9 or 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. Their lateral line runs the entire length of the body.
The Pacific Chub Mackerels are a coastal pelagic species found from the surface to depths of up to 300 meters (985 feet). They reach a maximum length of 64 cm (25 inches) and weight of 2.9 kg (7.4 pounds). They are normally found within 37 km (20 miles) from shore in waters with temperatures between 10oC (50oF) and 22oC (72oF). Young reside around sandy beaches and kelp beds while adults are found in deeper waters. They form large compact structured schools of thousands of individuals and may also form schools with Pacific Bonito, Sarda chiliensis, Jack Mackerel, Trachurus symmetricus, and Pacific Sardine, Sardinops sagax to compete for food. They undergo extensive summer migrations to cooler waters. Adults are vertical migrators found on the bottom during daylight hours and moving up during the nighttime to opportunistically and non-selectively feed on copepods and other crustaceans, fish, and squids. They rely heavily on camouflage for protection from predation being a favorite prey of predatory birds, sea lions, billfish, sharks, various tuna, White Sea Bass, and Yellowtail. Reproduction is via batch spawning with each female releasing between 100,000 and 400,000 eggs per annum with eggs and larvae being pelagic. They have a lifespan of up to eughteen years. Very little is known about their behavioral patterns.
In Mexican waters the Pacific Chub Mackerel are found in all waters of the Pacific with the exception that they are absent from Puerto Vallarta southward along the west coast of the mainland.
The Pacific Chub Mackerel is easy to identify and cannot be confused with any other species, however, it is virtually identical to the Atlantic Chub Mackerel, Scomber colias (belly with markings), which is found only in the Atlantic Ocean.
The Pacific Chub Mackerels are targeted commercially and harvested in purse seines at levels that approach 3,500,000 tons per annum. They are sold fresh, frozen, canned, and pickled for human consumption; they are also canned for pet food and used in Chinese medicine. They are a small highly energetic prized live bait. In the greater Los Cabos area during the months of December, January, and February, they are readily caught by the hundreds utilizing Sabiki Rigs (known locally as “Lucky Joe Rigs”) off the bottom over sandy terrain in deep waters by both recreational anglers and commercial bait salesmen who then sell them to marlin fishermen for $3.00 each. They are also a mainstay of pier fishermen in the greater San Diego area. As an exceptional live bait they are fished fly-lined, slow trolled, or sent down deep with a bottom rig attached to a 7/0 hook. From a conservation perspective, they are currently classified as of Least Concern with stable populations.
Pacific Chub Mackerel, Scomber japonicus. Fish caught from coastal waters off Point Palmilla, Baja California Sur, February 2016. Length: 20.0 cm (7.9 inches).
Pacific Chub Mackerel, Scomber japonicus. Fish caught from coastal waters off Santa Cruz, California, May 2016. Length: 19.2 cm (7.6 inches). Catch, photo and identification courtesy of Andrew Hansen, Santa Cruz, CA.